Tag Archives: milky way

The Andromeda Galaxy. Credit: Wikimedia Commons.

The Milky Way once had a large sister galaxy — but Andromeda devoured it

The Andromeda Galaxy. Credit: Wikimedia Commons.

The Andromeda Galaxy. Credit: Wikimedia Commons.

Billions of years ago, the Milky Way once had a huge sister galaxy, according to a surprising new study. Astronomers found that this long-lost sibling was devoured by the Andromeda galaxy, the largest galaxy in the Local Group and our closest galactic neighbor — and we’re next!

“Astronomers have been studying the Local Group — the Milky Way, Andromeda and their companions — for so long,” study co-author Eric Bell, a professor of astronomy at the University of Michigan (UM), said in a statement. “It was shocking to realize that the Milky Way had a large sibling, and we never knew about it.”

Androdema, also known as M32, is considered to be the largest galaxy in a group of 54 galaxies, which astronomers refer to as the Local Group. However, a recent study published this year, which used a new tool to measure the galaxy, suggests that Andromeda is about the same size as the Milky Way, which is traditionally seen as the second largest in the galaxy group.

In any event, Andromeda is huge — and it didn’t reach its king-sized status by accident. Astronomers think that during its rich history, Andromeda has collided, shredded, and appropriated hundreds of smaller galaxies.

It’s almost impossible to discern what happened to each of these lost galaxies. However, Bell and colleagues were lucky — they found that a faint halo of stars in the outer reaches of Andromeda mostly got there as a result of the shredding of a single large galaxy. Simulations that backtrack the collision in time suggest that about two billion years ago Andromeda must have merged with the onetime third-biggest member of the Local Group. The timing seems right too — a team of French researchers independently determined earlier this year that Andromeda likely underwent an important merger between 1.8 billion and 3 billion years ago.

“It was a ‘eureka’ moment. We realized we could use this information of Andromeda’s outer stellar halo to infer the properties of the largest of these shredded galaxies,” said lead author Richard D’Souza, a postdoctoral researcher at UM.

This galaxy, called M32p, which was shredded by the Andromeda galaxy, was at least 20 times larger than any galaxy which merged with the Milky Way over the course of its lifetime. M32p must have been massive, possibly once being at some point the third largest galaxy in the Local Group after the Andromeda and the Milky Way galaxies.

The devoured galaxy, called M32p, isn’t entirely gone. Instead, the astronomers think that Andromeda’s enigmatic M32 satellite galaxy is actually the surviving center of the Milky Way’s long-lost sibling — the remnants of a galactic corpse. Previously, scientists had no clue how M32, with its many contradictory features, could have surfaced. M32 is the smallest galaxy in the Messier catalog: just 6,500 light years across, with ~3 billion solar masses of material.

“M32 is a weirdo,” Bell continued. “While it looks like a compact example of an old, elliptical galaxy, it actually has lots of young stars. It’s one of the most compact galaxies in the universe. There isn’t another galaxy like it.”

The findings will help scientists improve their basic understanding of how galaxies form and evolve. For instance, it was previously thought that huge, dramatic crashes destroy the disks of spiral galaxies, turning them into the boring elliptical variety. However, Andromeda still retains its spiral shape, showing that this assertion is no rule.

“The Andromeda Galaxy, with a spectacular burst of star formation, would have looked so different 2 billion years ago,” Bell said. “When I was at graduate school, I was told that understanding how the Andromeda Galaxy and its satellite galaxy M32 formed would go a long way towards unraveling the mysteries of galaxy formation.”

Perhaps most importantly, the Andromeda-M32p collision will teach us what to expect from the galactic cannibal when it will have a taste of its largest meal yet — the Milky Way. The two galaxies will likely collide four billion years from now in an epic clash of the titans that will light the sky in other worlds that are far away enough from the mayhem.

A series of stills showing the Milky Way-Andromeda merger, and how the sky will appear different from Earth as it happens. Credit: NASA; Z. LEVAY AND R. VAN DER MAREL, STSCI; T. HALLAS; AND A. MELLINGER.

A series of stills showing the Milky Way-Andromeda merger, and how the sky will appear different from Earth as it happens. Credit: NASA; Z. LEVAY AND R. VAN DER MAREL, STSCI; T. HALLAS; AND A. MELLINGER.

The findings were reported in the journal Nature Astronomy.

Andromeda Galaxy.

Two billion years ago, Andromeda ‘ate’ a sister-galaxy of the Milky Way

Our closest galactic neighbor, Andromeda, seems to like the taste of its brethren.

Andromeda Galaxy.

The Andromeda Galaxy imaged through a hydrogen-alpha filter.
Image credits Adam Evans.

Researchers from the University of Michigan (UoM) report that the Andromeda galaxy smote and consumed one of its brethren some two billion years ago. Although its victim was shredded almost completely, the team pieced together evidence of the collision from the thin halo of stars that spans the gap between Andromeda and its enigmatic companion, Meiser 32 (M32).

The discovery helps further our understanding of how galaxies like the Milky Way evolve, and of their behavior during large mergers.

Family dinner

Our own galaxy, the Milky Way, and our closest neighbor, Andromeda, are the two largest members of a group known as the Local Group (of galaxies). The extended family includes some 54 different galaxies — most of them dwarf galaxies acting as satellites for their larger relatives — all orbiting around a point roughly between Andromeda and the Milky Way.

It may sound idyllic, but researchers have found that at least one member of this group found its demise at the hands of Andromeda. This once-galaxy, christened M32p, was the third-largest member of the Local Group — a distinction that now falls on the galaxy Triangulum.

The team started their research using data pertaining to the halo of stars around Andromeda. It’s not a unique feature; many galaxies harbor such wispy-thin groupings of stars around their bulk, the final remnants of smaller galaxies that they absorbed over time. Since Andromeda is so large and rich in matter (it has over double the diameter of the Milky Way and double its number of stars), the researchers expected it to have consumed hundreds of smaller galaxies — which they thought would make it impossible to study a single such meal.

M32.

Size comparison between M32p and today’s M32.
Image credits Richard D’Souza; for the image of M64: NOAO/AURA/NSF.

However, the team’s computer simulations revealed that although Andromeda did dine on many of its companion galaxies, most stars in the outer halo originate from a single, large galaxy. Piecing the evidence together to peer back in time, the team found that M32p would have been massive — likely the third-largest in the Local Group, after Andromeda and the Milky Way. The paper adds that M32p was at least 20 times larger than any galaxy the Milky Way ever merged with.

“The stars in Andromeda are very metal-rich and considerably young,” Richard D’Souza, lead author of the paper, explained in an e-mail. “In general, the larger the galaxy the more metal rich the stars are. We suspected that since the stars in the halo of Andromeda were so metal-rich, it must have come from a large metal-rich galaxy.”

One big bite

A metal-rich halo large enough to encompass a galaxy such as Andromeda could only be formed “through a single large merger,” he adds, noting that “there are not many smaller galaxies in the Universe to build up to the mass of the halo”.

“In terms of a business analogy, galaxies also grow through mergers and acquisitions. In order for a major company to grow at a very fast pace, it would need to acquire a similar large company into its business. Such was the case with Andromeda,” D’Souza adds.

The findings call into question our models of how mergers between two massive galaxies play out. Until now, astronomers believed that such an event would flatten the disk of a spiral galaxy into an elliptical one, but Andromeda’s disk evidently pulled through still very spiral-shaped. Some effects of this collision can still be seen, D’Souza told me. Among them are the thickness of Andromeda’s disk and the higher speeds its stars travel at (90 km/s compared to around 30 km/s in the Milky Way).

Collision path.

The process of shredding of the large galaxy M32p by the Andromeda (M31) galaxy which eventually resulted in M32 and a giant halo of stars.
Image credits Richard D’Souza; M31, courtesy of Wei-Hao Wang; Stellar halo of M31: AAS/IOP.

Still, he admits that it came as “a major surprise” that Andromeda could retain its spiral shape following this collision. One explanation could be that the particular angle of the collision between the two galaxies helped keep Andromeda spiral-like, “but we need to run more computer simulations to see which set of orbits helps preserve the disk”.

Beyond this, it helps us better understand Andromeda’s evolution over time. The timing of the merger coincides with a burst of intense star formation in Andromeda two billion years ago. All this star-forming activity also suggests that M32p must have been gas-rich in order to supply enough building blocks.

Finally, the findings point to Andromeda’s mysterious, compact, and very dense, satellite galaxy M32 (the one today) as the last sliver of the once-mighty galaxy — the naked core. This piece of data could help explain why we see so few galaxies similar to M32 zipping around in the universe.

“M32 is a weirdo,” co-author Eric Bell, UoM professor of astronomy, said in a press release. “While it looks like a compact example of an old, elliptical galaxy, it actually has lots of young stars. It’s one of the most compact galaxies in the universe. There isn’t another galaxy like it.”

“Galaxies like M32 are considerably rare in the Universe,” D’Souza adds. “The term used for them in the literature is called ‘compact ellipticals’, and they are one of the most rarest galaxies in the Universe. We do know a dozen or so compact ellipticals in the nearby Universe, and we have inferred that further out (where we cannot resolve them), the number is equally low.”

As part of the paper, the team also found that the merger scenario could help explain the scarcity of M32-like objects. It seems the secret is not just in the merging process itself, but also in the particular makeup of the galaxies involved. “What one really needs is a galaxy with a high central surface density of stars comparable to M32,” D’Souza explains. It seems to be quite a rare occurrence — the team only identified 8 potential progenitors for M32-like objects.

Their study may alter the traditional understanding of how galaxies evolve, the researchers say. The realization that Andromeda’s disk survived an impact with a massive galaxy flies in the face of our current models, which suggests that such large interactions would destroy disks and form an elliptical galaxy.

It went so fundamentally against the grain of our understanding of galaxy-formation that, previously, we didn’t even consider the possibility that this scenario could have ever occurred.

“Astronomers have been studying the Local Group–the Milky Way, Andromeda and their companions–for so long. It was shocking to realize that the Milky Way had a large sibling, and we never knew about it,” Bell concludes.

Such investigative methods can be applied to other galaxies as well, the team explains, to help us tease out the merger history of other galaxies besides Andromeda.

The paper “The Andromeda galaxy’s most important merger about 2 billion years ago as M32’s likely progenitor” has been published in the journal Nature Astronomy.

Scientists just found the first relic galaxy — it’s remained unchanged since the early universe

According to previous calculations by astronomers, one in every thousand massive galaxies is a relic of the early universe. It’s an almost esoteric term that describes a galaxy whose properties are still largely the same as when it formed billions of years ago. Now, scientists say they’ve finally identified one for the first time.

Researchers at the Instituto de Astrofísica de Canarias (IAC) and the University of La Laguna (ULL) used ground-based telescopes to study NGC 1277, a galaxy located 225 million light-years away, in the heart of the Perseus Cluster — the largest concentration of galaxies close to the Milky Way. 

Their initial observations suggested something odd about the globular clusters surrounding NGC 1277. Globular clusters are spherical collections of ancient stars, formed at the same time as the galaxy, that orbit the galactic core as a satellite. Scientists class globular clusters in two distinct groups: red globular clusters, which are formed in massive galaxies nearer to their centers, and blue ones, which are found more toward the outskirts of the galaxy. Red globular clusters have a higher concentration of heavier elements (hence the color), while blue ones have a lower fraction of metals.

When the researchers pointed the Hubble Space Telescope towards the globular clusters surrounding NGC 1277, they struck gold. The observation revealed that the galaxy only has only red globular clusters, which have remained unchanged since they were formed many millions of years ago along with the galaxy.

“Globular cluster systems are very sensitive to the history of galaxy formation” explained Michael Beasley, the first author of the article and a researcher at Instituto de Astrofísica de Canarias (IAC), who said that “this is the first time a galaxy so massive has been observed with so few blue globular clusters.”

NGC 1277 is composed of a thousand billion stars, and its relatively close proximity to Earth provided an excellent opportunity to find a rare wonder of the cosmos. “The galaxy NGC 1277 gives us a unique opportunity to study a “primitive” galaxy in the “local” universe” adds Ignacio Trujillo, another of the article’s authors.

According to the researchers, when the galaxy formed, it used to birth stars at a rate of 1,000 per year, whilst the Milky Way is currently forming only one star per year. The team believes that the reason why the galaxy has remained unchanged during all this time, retaining its original form and composition, is because it formed as a satellite to the central galaxy of the Perseus cluster. Since the cluster absorbed most of the material that could have fallen into NGC 1277, this dynamic has caused the relic galaxy to evolve differently.

“We argue that the colour distribution of the cluster system of NGC 1277 indicates that the galaxy has undergone little (if any) mass accretion after its initial collapse, and use simulations of possible merger histories to show that the stellar mass due to accretion is probably at most ten percent of the total stellar mass of the galaxy. These results confirm that NGC 1277 is a genuine relic galaxy and demonstrate that blue clusters constitute an accreted population in present-day massive galaxies,” the authors wrote in the journal Nature.

The authors hope to find more relic galaxies in the future using the Hubble Space Telescope and its successor, the James Webb Space Telescope.

Scientific reference: BEASLEY, Michael A. et al. “A single population of red globular clusters around the massive compact galaxy NGC 1277”, Nature. DOI: 10.1038/nature25756

Researchers map out the age of the Milky Way’s “heart”

Astronomers have developed the first age-map of the Milky Way galaxy, showing a period of star formation that lasted for 4 billion years.

NGC 1300, a barred spiral galaxy, similar in many ways to the Milky Way. For obvious reasons, we don’t have any real images of our own galaxy. Image credits: Hubble Space Telescope / NASA.

As far as galaxies go, the Milky Way is pretty average. It’s a barred spiral galaxy — a spiral-shaped galaxy with a central bar-shaped structure composed of stars — with a diameter between 100,000 and 180,000 light-years. It’s estimated that our galaxy hosts 100-400 billion stars and at least 100 billion stars.

At its center (the “bar” in the “barred spiral galaxy”), the Milky Way features a star bulge — a massive star population thousands of light years in diameter, containing about a quarter of all the stars in the galaxy. This bulge has two components: a population of metal-poor stars that have a spherical distribution, and a population of metal-rich stars that wrap around them like a waistline or a two-lobed peanut.

[alert style=”alert-info” close=”false”]For astronomers, all elements other than hydrogen and helium are referred to as ‘metals’ — even though elements such as oxygen and carbon which are considered non-metals by chemists. [/alert]

The infrared map constructed from the VISTA Variables in the Via Lactea (VVV) survey of the inner Milky Way showing the studied areas. Credit: ESO/M. Rejkuba/F. Surot Madrid / E. Valenti.

Analyses of these two areas have yielded conflicting results. Now, an international team of researchers has used both simulated and observed data, from millions of stars to map the age and development of these intriguing stars.

“We analysed the colour and brightness of stars to find those that have just reached the point of exhausting their hydrogen fuel-burning in the core, which is a sensitive age indicator. Our findings were not consistent with a purely old Milky Way bulge, but require star formation lasting around 4 billion years and starting around 11 billion years ago. The youngest stars that we see are at least 7 billion years old, which is older than some previous studies had suggested.”

Results paint an interesting overall picture, but it’s still hard to accurately resolve smaller areas within the bulge. Ultimately, researchers hope to create a more accurate, detailed map of the Milky Way core.

Artist’s impression showing the peanut shaped structure in the central bulge. Credit: ESO/NASA/JPL-Caltech/M. Kornmesser/R. Hurt.

Francisco Surot Madrid, the co-lead author of the study, concludes:

“Previous studies have told us that the metal-rich stars in the bar are likely to be the youngest stars. Whilst we can’t disentangle which star belongs to the bar/peanut or the spheroid component in the data we are using, our results tell us that the bar was already formed about 7 billion years ago and there were no large amounts of gas inflowing and forming stars along the bar after that.”

The study hasn’t been peer-reviewed. Results will be presented at the European Week of Astronomy and Space Science.

An all-sky map showing the radial velocity of neutral hydrogen gas belonging to the high-velocity clouds of the Milky Way and two neighbouring galaxies, the Large and Small Magellanic Clouds. Credit: ICRAR.

Ginormous hydrogen clouds whizz around the Milky Way at phenomenal speeds

Right outside the Milky Way plane, strange and enormous clouds of hydrogen zip through intergalactic space at incredible speeds. Scientists have known for some time that these mysterious objects exist but it’s only recently that they’ve been mapped in great detail.

An all-sky map showing the radial velocity of neutral hydrogen gas belonging to the high-velocity clouds of the Milky Way and two neighbouring galaxies, the Large and Small Magellanic Clouds. Credit: ICRAR.

An all-sky map showing the radial velocity of neutral hydrogen gas belonging to the high-velocity clouds of the Milky Way and two neighboring galaxies, the Large and Small Magellanic Clouds. Credit: ICRAR.

Everything about these clouds speaks to their grand scale. Some of the clouds are millions of times the mass of the sun and stretch over tens of thousands of light-years in diameter.

The hydrogen clouds cover about 13 percent of the night sky but it took the powerful radio telescopes employed by Australian scientists at the International Center for Radio Astronomy Research (ICRAR) to peer inside them. The new data enabled the researchers to construct a far more detailed map of the clouds that now shows never before seen features such as clumps and branch-like structures.

“It’s something that wasn’t really visible in the past, and it could provide new clues about the origin of these clouds and the physical conditions within them,” said Tobias Westmeier, one of ICRAR researchers involved in the new research, in a statement.

map-sky

A false-color all-sky map combining the column density and radial velocity of high-velocity neutral hydrogen gas. Credit: ICRAR.

What makes these clouds particularly interesting, yet challenging, to study is the fact they move differently from the rotational movement of the galaxy itself. Traveling at break-neck speeds of 43.5 to 56 miles per second, the clouds also seem to be in a hurry to move towards or away from us.

It’s not clear at all at this point how the clouds got here or why they behave the way they do. It could be that the odd objects are leftovers from the formation of the galaxy itself. Alternatively, they could be sourced from some alien galaxy only to be caught in the Milky Way’s gravitational embrace.  This latter hypothesis seems to carry more weight given the chemical composition of the hydrogen-rich clouds differs from what you’d typically expect to find within the Milky Way.

Maybe you, dear reader, can help to answer this question. The map is freely available online for anyone to study.

The new findings appeared in the Monthly Notices of the Royal Astronomical Society.

One of the Milky Way's sibling as seen by the Sloan Digital Sky Survey.

The Milky Way might not be your typical spiral galaxy but is it unique?

Our galactic home, the spiral-armed Milky Way, might not behave like similar galaxies, according to findings of the Satellites Around Galactic Analogs (SAGA) Survey. The findings suggest current models for both galactic and stellar formation might require revising.

“We use the Milky Way and its surroundings to study absolutely everything. Hundreds of studies come out every year about dark matter, cosmology, star formation, and galaxy formation, using the Milky Way as a guide. But it’s possible that the Milky Way is an outlier,” said Marla Geha, an astrophysicist at Yale University and lead author of the new paper on the subject.

One of the Milky Way's sibling as seen by the Sloan Digital Sky Survey.

One of the Milky Way’s sibling as seen by the Sloan Digital Sky Survey.

Just like moon orbits Earth or Earth orbits the sun, so do other smaller galaxies revolve around the Milky Way’s core, such as the Large and Small Magellanic Clouds. Andromeda, a neighboring spiral galaxy, also has similar satellites. In turn, the Milky Way revolves around the Local Group center of mass, located somewhere between Andromeda and the Milky Way. Nothing is stationary and everything travels with respect to something else.

The movements and behaviors of galactic satellites can indirectly offer information about their galactic parent. In 2012, an international collaboration launched the SAGA Survey with the stated goal of studying satellite galaxies around a hundred or so spiral galaxies similar to the Milky Way. So far, five such galaxies and their satellites have been tracked. To reach definite conclusions, at least 25 galaxies should be studied, a target which ought to be reached within two years.

Already, however, the survey is reporting conflicting findings with what we’d expect. According to Geha, the satellites of the Milky Way’s siblings behave significantly different. One important distinction is our galactic satellites are mostly ‘inert’ in terms of new star formation while those of the Milky Way’s siblings are far more active, pumping out new stars at a high rate.

As such, the work puts the Milky Way in a far grander context. By one estimate, there are one hundred billion galaxies in the observable universe but we’re only beginning how similar or, by contrast, dissimilar these galaxies can be.

“I really want to know the answer to whether the Milky Way is unique, or totally normal. By studying our siblings, we learn more about ourselves,” Geha said.

Researchers find tantalizing evidence of mid-sized black hole in the Milky Way

We know there’s a supermassive black hole at the center of our galaxy, and now we have evidence for another one. This ‘mid-sized’ black hole is still 100,000 times more massive than our sun.

Artistic representation of a black hole. Image credits: NASA / ESA.

It’s widely accepted that most galaxies have a supermassive black hole at their core. While the existence of such a black hole in our galaxy has almost been settled, not the same can be said for other types of black holes. Astronomers have long chased evidence of mid-sized black holes — black holes larger than the ones formed from a single star, but still much smaller than supermassive black holes. Now, they might have finally found one, and it suggests that our galaxy grew by cannibalizing other galaxies.

In a study published in Nature Astronomy, scientists led by Tomoharu Oka from Keio University, Japan, describe a “peculiar” molecular cloud sitting near the center of the Milky Way. They found that this molecular cloud exhibited some properties which are hard to explain, but would fit in very nicely a with “gravitational kick” caused by an “invisible compact object.”

They modeled their data and found that the structure is a very promising candidate for an intermediary black hole (IMBH) — a hypothetical class of black hole with mass in the range 100 to one million solar masses. This particular black hole would be on the range of 100,000 solar masses. We’re not really sure that IMBHs even exist, as they’ve proven to be quite elusive, but this seems to be a very promising candidate.

“It’s a very careful paper and they have gorgeous data. It’s the most promising evidence so far” for an intermediate mass black hole, says astronomer Kevin Schawinski of the Swiss Federal Institute of Technology in Zurich, who was not involved in the study..

Brooke Simmons at the University of California, San Diego, who was also not involved in the study, described it as “careful detective work.”

But if this is the case, then how did the black hole form, and how did it get to the near-center of the galaxy? IMBHs are too big to form from the collapse of a single star — which is how stellar black holes form. They also don’t have the extreme conditions required to become a supermassive black hole. There are three main theories regarding their formation:

  • the first is through the merging of several stellar black holes;
  • the second is the runaway collision of massive stars which then collapse together;
  • the third is that they are primordial black holes formed in the Big Bang.

Oka and Keio believe this IMBH formed through the first option. They propose that a dwarf galaxy was once subsumed by the Milky Way, and its core became this black hole. A lot more evidence is still needed to back up this claim, and that’s exactly what the two astronomers want to do. They will continue to observe the area and follow it long term, looking for clues to its nature and mass.

“The most exciting thing is the likelihood that intermediate mass black holes are real,” Schawinski says. “We know very little about how black holes form.” But if Oka’s team or others are able to find a population of such objects, “we can put our ideas to the test.”

As the authors themselves put it, confirming the existence of such objects would make a considerable contribution not only to astronomy, but to modern physics itself.

“Further detection of such compact high-velocity features in various environments may increase the number of non-luminous black hole candidate and thereby increase targets to search for evidential proof of general relativity. This would make a considerable contribution to the progress of modern physics.”

Journal Reference: Tomoharu Oka, Shiho Tsujimoto, Yuhei Iwata, Mariko Nomura & Shunya Takekawa — Millimetre-wave emission from an intermediate-mass black hole candidate in the Milky Way. doi:10.1038/s41550-017-0224-z

Artist's representation of what a Y-class brown dwarf might look like.

Researchers spot the biggest brown dwarf ever, trailing at the edge of the Milky Way

An international research team has found the largest brown dwarf we’ve ever seen, and it has ‘the purest’ composition to boot. Known as SDSS J0104+1535, the dwarf trails at the edges of the Milky Way.

An artists' representation of a brown dwarf with polar auroras.

An artists’ representation of a brown dwarf with polar auroras.
Image credits NASA / JPL.

Brown dwarfs — they’re like stars, but without the spark of love. They’re much too big to be planets but they’re too small to ignite and sustain fusion, so they’re not (that) bright and warm and so on. Your coffee is probably warmer than some Y-class brown dwarfs, which sit on the lower end of their energy spectrum. The coldest such body we know of, a Y2 class known as WISE 0855−0714, is actually so cold (−48 to −13 degrees C / −55 to 8 degrees F) your tongue would stick to it if you could lick it.

But they can still become really massive, as an international team of researchers recently discovered: nestled among the oldest of stars in the galaxy at the halo of our Milky Way, some 750 light years away from the constellation Pisces, they have found a brown dwarf which seems to be 90 times more massive than Jupiter — making it the biggest, most massive brown dwarf we’ve ever seen.

Named SDSS J0104+1535, the body is also surprisingly homogeneous as far as chemistry is concerned. Starting from its optical and near-infrared spectrum measured using the European Southern Observatory’s Very Large Telescope, the team says that this star is “the most metal-poor and highest mass substellar object known to-date”, made up of an estimated 99.99% hydrogen and helium. This would make the 10-billion-year-old star some 250 times purer than the Sun.

Artist's representation of what a Y-class brown dwarf might look like.

Y u so cold?
Image credits NASA / JPL-Caltech.

 

“We really didn’t expect to see brown dwarfs that are this pure,” said Dr Zeng Hua Zhang of the Institute of Astrophysics in the Canary Islands, who led the team.

“Having found one though often suggests a much larger hitherto undiscovered population — I’d be very surprised if there aren’t many more similar objects out there waiting to be found.”

From its optical and infrared spectrum, measured using the Very Large Telescope, SDSS J0104+1535 has been classified as an L-type ultra-cool subdwarf — based on a classification scheme established by Dr Zhang.

The paper “Primeval very low-mass stars and brown dwarfs – II. The most metal-poor substellar object” has been published in the journal Monthly Notices of the Royal Astronomical Society.

On the left is Pisces A, 19 million light-years away. On the right we can see Pisces B, which is around 30 million light-years way. Credit: NASA, ESA, and E. Tollerud (STScI)

Two dwarf-galaxies have left the wilderness to join a galactic party

On the left is Pisces A, 19 million light-years away. On the right we can see Pisces B, which is around 30 million light-years way. Credit: NASA, ESA, and E. Tollerud (STScI)

On the left is Pisces A, 19 million light-years away. On the right we can see Pisces B, which is around 30 million light-years way. Credit: NASA, ESA, and E. Tollerud (STScI)

Hubble just spotted two dwarf galaxies leave the galactic wilderness for a much more crowded region, drawn in by gravity. The pair previously inhabited a region of the Universe sparsely populated with galaxies, the 150 million light-years across Local Void. Astronomers say the galaxies are now ready to seriously nurse many new stars as they enter a more welcoming breeding ground rich in gas and dust.

“These Hubble images may be snapshots of what present-day dwarf galaxies may have been like at earlier epochs,” said lead researcher Erik Tollerud of the Space Telescope Science Institute in Baltimore, Maryland. “Studying these and other similar galaxies can provide further clues to dwarf galaxy formation and evolution.”

A dwarf galaxy is a small galaxy composed of about 100 million up to several billion stars. Though impressive, it’s still a trifle even when compared to a medium-sized galaxy like the Milky Way which hosts 200–400 billion stars. But dwarf galaxies, which are extremely faint and hard to detect, are extremely interesting for astronomers.

First of all, they’re the most numerous kind of galaxies in the universe. Secondly, dwarfs are the Milky Way’s closest neighbours allowing high-quality data to be gathered by telescopes. Dwarfs were also the building blocks of larger galaxies which formed billions of years ago — after all, everything started out small. We owe a lot of what we know about how galaxies form to dwarfs.

These recent dwarfs spotted by the Hubble Telescope, Pisces A and B, each contain only about 10 million stars — very sparsely populated even by galactic dwarven standards.

“These galaxies may have spent most of their history in the void,” Tollerud explained. “If this is true, the void environment would have slowed their evolution. Evidence for the galaxies’ void address is that their hydrogen content is somewhat high relative to similar galaxies. In the past, galaxies contained higher concentrations of hydrogen, the fuel needed to make stars. But these galaxies seem to retain that more primitive composition, rather than the enriched composition of contemporary galaxies, due to a less vigorous history of star formation. The galaxies also are quite compact relative to the typical star-forming galaxies in our galactic neighborhood.”

Astronomers found the dwarf pair while surveying hydrogen content in the Milky Way using radio telescopes. Thousands of small blobs packed with dense hydrogen gas were discovered within our galaxy, but some 30 to 50 of these blobs seemed to be located outside of it. Tollerud and colleagues then selected a couple which seemed like worthy candidates for nearby galaxies and asked permission to use Hubble’s Advanced Camera for Surveys to analyse them.

For this purpose, Hubble is particularly well-suited thanks to its sharp vision which can resolve individual stars and reliably estimate a galaxy’s distance. The distance is particularly important for determining brightness, as well as for calculating how far a galaxy is from a void.

The scientists found Pisces A is 19 million light-years away from Earth while Pisces B is roughly 30 million light-years away. Each galaxy has 20 to 30 bright blue stars, signifying they’re still very young — less than 100 million years old. At some point, the galaxies doubled their star formation rate as they closed in a more crowded sector. This star formation rate may slow down if the dwarfs draw too near a much larger galaxy and become satellites.

“The galaxies could even probably stop forming stars altogether, because they will stop getting new gas to make stars,” Tollerud said. “So they will use up their existing gas. But it’s hard to tell right now exactly when that would happen, so it’s a reasonable guess that the star formation will ramp up at least for a while.”

Findings appeared in the Astrophysical Journal.

 

Scientists uncover unique speed and direction of Milky Way’s spinning ‘halo’

A team of NASA-funded astronomers from the University of Michigan has discovered that the hot gas in the Milky Way’s halo is spinning in the same direction, as well as at a similar speed, as its disk.

Illustration of the Milky Way's high temperature gaseous halo (seen in blue). Credit: NASA/CXC/M.Weiss/Ohio State/A Gupta et al.
Illustration of the Milky Way’s high temperature gaseous halo (seen in blue).
Credit: NASA/CXC/M.Weiss/Ohio State/A Gupta et al.

The Milky Way’s disk contains our stars, planets, gas and dust, and the findings from the new study shed light on how stars, planets, and galaxies such as our own form from individual atoms.

“This flies in the face of expectations,” said Edmund Hodges-Kluck of the University of Michigan and lead author of the study. “People just assumed that the disk of the Milky Way spins while this enormous reservoir of hot gas is stationary – but that is wrong. This hot gas reservoir is rotating as well, just not quite as fast as the disk.”

The study used data from the European Space Agency’s (ESA’s) XXM-Newton telescope to examine the nature of the Milky Way’s gaseous halo, which is composed of ionized plasma and is several times larger than its disk.

Motion creates shifts in the wavelengths of light and using lines of hot oxygen, the team was able to pinpoint these shifts. These shift measurements revealed that the our galaxy’s halo spins in the same direction as its disk, as well as at a similar speed – the halo spins at approximately 400,000 miles per hour compared to the disk, which spins at around 540,000 miles per hour.

“The rotation of the hot halo is an incredible clue to how the Milky Way formed,” Hodges-Kluck said. “It tells us that this hot atmosphere is the original source of a lot of the matter in the disk.”

The data could help scientists better understand the nature of dark matter, the mysterious undetectable matter that is believed to make up around 80 percent of the universe, as well as the other missing “normal” matter that appears to be missing from galaxy disks. The answers to these missing matter mysteries could lie in the gaseous halos of the universe’s many galaxies.

“Now that we know about the rotation, theorists will begin to use this to learn how our Milky Way galaxy formed – and its eventual destiny,” said Joel Bregman, a professor of astronomy from the University of Michigan and senior author of the study. “We can use this discovery to learn so much more – the rotation of this hot halo will be a big topic of future X-ray spectrographs.”

Journal Reference: THE ROTATION OF THE HOT GAS AROUND THE MILKY WAY. 27 April 2016. 10.3847/0004-637X/822/1/21

NASA’s Kepler Space Telescope discovers 104 new planets outside of Milky Way

Using data from NASA’s Kepler Space Telescope during the K2 mission in combination with observations from various Earth-based telescopes, an international team of astronomers has discovered 104 new exoplanets, four of which could hold the potential for life.

An illustration of NASA's Kepler Space Telescope during the K2 mission. Credit: NASA/JPL-Caltech

An illustration of NASA’s Kepler Space Telescope during the K2 mission. Credit: NASA/JPL-Caltech

Prior to the K2 mission, the Kepler focused specifically on measuring the frequency with which planets with sizes and temperatures similar to the Earth occurred around sun-like stars. Now, it focuses on cooler and smaller red dwarf-type stars, which are much more common in the Milky way than sun-like stars.

The new mission also focuses on both the northern and southern hemispheres, as opposed to the initial mission, which was limited to examining a specific portion of the sky in the northern hemisphere.

“Kepler’s original mission observed a small patch of sky as it was designed to conduct a demographic survey of the different types of planets,” said Ian Crossfield of the University of Arizona’s Lunar and Planetary Laboratory and leader of the research. “This approach effectively meant that relatively few of the brightest, closest red dwarfs were included in Kepler’s survey. The K2 mission allows us to increase the number of small, red stars by a factor of 20 for further study.”

Of the 104 new exoplanets discovered outside of our solar system, four are of particular interest due to their potential similarities to Earth. The set of planets are between 20 to 50 percent larger than Earth and orbit a star less than half the size of the sun. In addition, two of them are believed to experience radiation levels from their star that are comparable to those experienced by the Earth.

Although the orbits of the new set of planets are fairly tight, Crossfield believes that the current data suggests that we must consider the possibility of life on such planets until further research says otherwise

“Because these smaller stars are so common in the Milky Way, it could be that life occurs much more frequently on planets orbiting cool, red stars rather than planets around stars like our sun,” he said.

The findings were published in The Astrophysical Journal Supplement Series.

Artist impression of 2MASS J2126. Credit: Neil Cook, University of Hertfordshire

Lonely planet is actually part of the largest planetary system in the Milky Way

Astronomers used to think that a lonely planet called 2MASS J2126 was without a parent star, drifting like an orphan through interstellar space. A team now says the planet isn’t a rogue — it’s just that it has a really big orbit, about 7,000-times the size of Earth’s orbit around the sun. This makes the solar system it belongs to the largest in the Milky Way. Quite the plot twist.

Artist impression of 2MASS J2126. Credit: Neil Cook, University of Hertfordshire

Artist impression of 2MASS J2126. Credit: Neil Cook, University of Hertfordshire

A long distance relationship

“This is the widest planet system found so far and both the members of it have been known for eight years, but nobody had made the link between the objects before,” said lead author Dr Niall Deacon of the University of Hertfordshire in a statement about the findings.

When astronomers first spotted 2MASS J2126, they thought it was a rogue planet. These free floating planets are most intriguing for researchers. They are not orbiting a star but instead are wandering through the galaxy. These are either ancient planets formed in the early Universe or estranged daughters jettisoned out of their parent solar system. There could be 100,000 times more rogue planets than stars in our Milky Way galaxy alone, by some accounts, so 2MASS J2126 wasn’t that odd.

False colour infrared image. The arrows show the motion over the next 1,000 years. (Simon Murphy)

False colour infrared image. The arrows show the motion over the next 1,000 years. (Simon Murphy)

Upon closer inspection, a team from UK, U.S. and Australia found that 2MASS J2126 is associated with a dwarf star. The catch is that they’re spaced apart by 1 trillion kilometers and it takes a full 900,000 years for 2MASS J2126 to complete a revolution around its star, as reported in the paper.

“How such a wide planetary system forms and survives remains an open question,” Simon Murphy of Australian National University said in a statement.

The planet and its solar system are 104-light-years away from Earth. But the researchers’ findings shouldn’t be all that surprising. Last week, ZME Science reported how astronomers found what they think is the solar system’s ninth planet — and it’s not Pluto. Unceremoniously dubbed ‘Planet Nine’, it’s believed to be 10 times bigger than Earth and orbit 20 times farther from the sun than Neptune. The researchers didn’t actually find the planet, but reckoned it must be somewhere inside the Kuiper Belt based on the influence it exerts on other objects.

First ‘growth chart’ developed for the Milky Way

The Milky Way has been around for at least 13.7 billion years, but it has its younger and older areas. Now, researchers from the Max Planck Institute for Astronomy in Heidelberg, Germany have created a map that shows how our galaxy grew in time, confirming the belief that it grew from the inside out.

Age distribution of red giant stars from the galactic center to the Milky Way’s outskirts. Blue are the youngest stars, while towards the middle, the red stars are the oldest. Image Credit: M. Ness & G. Stinson / MPIA

The gist of it is very simple: there are older star at the middle of the galaxy and younger ones towards the extremities, to it seems that our galaxy aged by growing up. The chart considered over 70,000 stars extending half-way through the Milky Way.

“Close to the centre of our galaxy, we see old stars that were formed when it was young and small. Farther out, we see young stars. We conclude that our galaxy grew up by growing out,” said Melissa Ness from the Max Planck Institute for Astronomy in Heidelberg in Germany, who led the study. “To see this, we needed an age map spanning large distances, and that is what this new discovery gives us,” she added.

In order to determine these ages, they studied red giants. Red giants are giant stars of low or intermediate mass (roughly 0.3–8 solar masses ) in a late phase of stellar evolution – they’re old. They’re also easy to observe, which makes them an ideal candidate for this type of study.

“If we know the mass of a red giant star, we know its age by using the fusion clock inside every star. Finding masses of red giant stars has historically been very difficult, but surveys of the galaxy have made new, revolutionary techniques possible,” said Marie Martig, co-author of the study.

The map, which was unveiled at the 227th annual meeting of the American Astronomical Society used data from the APOGEE survey and the Kepler Space Telescope.

“APOGEE is the ideal survey for this work because it can get high-quality spectra for 300 stars simultaneously over a large area of sky,” said Steve Majewski, principal investigator of the APOGEE survey. “Seeing so many stars at once means getting spectra of 70,000 red giants is actually possible with a single telescope in a few years’ time,” he added.

Not only was APOGEE ideal, but it was actually vital for this type of study. Even five years ago, when it wasn’t available,  such a map wouldn’t have been possible.

“The Kepler dataset gives you the mass of stars,” Ness said. “From mass, you can deduce age using stellar models.” That’s exactly what Ness and her colleagues did, for approximately 30,000 red giant stars in the Kepler dataset.

In the future, astronomers want to refine the results even more and create a more detailed map of how the galaxy evolved.

“APOGEE has nineteen elements for each star that it observes, and each of those is telling you about the conditions that the star formed from,” she said. “When the APOGEE 2 data is available, we want to analyze these elemental abundances along with ages and couple the information.”

A small section of the Milky Way photo showing Eta Carinae. © Lehrstuhl für Astrophysik, RUB

Biggest space picture ever: a 46 billion megapixel view of the Milky Way

After five years of painstakingly stitching together pictures of the Milky Way, astronomers from Ruhr University Bochum have finally completed their masterpiece: the largest ever space photo. It has a whooping 46 billion megapixel and  194 GB in file size. It’s so large, in fact, that the astronomers had to cut it in 268 sections for it be manageable.

A small section of the Milky Way photo showing Eta Carinae. © Lehrstuhl für Astrophysik, RUB

A small section of the Milky Way photo showing Eta Carinae. © Lehrstuhl für Astrophysik, RUB

I know what you’re thinking: ‘where can I see it?’ Well, the astronomers graciously built a dedicated web tool which you can use to zoom in and out on different sections of your choosing, basking in the glow of distant stars or quasars. Right now, it’s a bit crowded and the server’s taking a strain, so be sure to check back if the tool isn’t loading sections properly.

Another section, this time showing the M8 nebula. © Lehrstuhl für Astrophysik, RUB

Another section, this time showing the M8 nebula. © Lehrstuhl für Astrophysik, RUB

Of course, there’s much more the project than a pretty picture. Dr. Rolf Chini and colleagues first began to compile this work to map out the variable phenomena in the Milky Way, which refers to blinking stars. A change in a star’s brightness means that an object must have obscured it, like a planet. Using the telescope in the  Atacama Desert in Chile, the researchers found 50,000 objects of variable brightness previously unknown to science.

Milky Way Galaxy May be Way Larger Than Previously Thought

It is generally accepted that our galaxy has a diameter of nearly 100,000 light-years. However, findings of a new research, published in the Astrophysical Journal, suggest that the Milky Way may actually be 50% larger than previously thought.

The Milky Way is a spiral galaxy containing our solar system. From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within, but if you could see it from the outside, you’d see spiral arms revolving around a central mass. Now, researchers believe it’s time we make a correction regarding its estimated size.

Rensselaer Polytechnic Institute Professor Heidi Jo Newberg and his team revisited astronomical data from the Sloan Digital Sky Survey; they report that the “Monoceros Ring” — a band of stars wrap around our galaxy three times — are actually a part of the Milky Way. If this is indeed the case, then the galaxy is 50% larger than previously believed.

Image via Sol Station.

Image via Sol Station.

“For 15 years, there’s been a controversy in the field where half the astronomers think it’s a tidal stream and half the astronomers think it’s something in the disk. I was in the stream camp,” Heidi Newberg from the Rensselaer Polytechnic Institute in New York, and a co-author of the paper, said in an email. “It now looks to me like it’s part of the disc.”

Yan Xu, a scientist at the National Astronomical Observatories of China and also an author of the paper believes that there may be even more ripples we have yet to discover.

“Going into the research, astronomers had observed that the number of Milky Way stars diminishes rapidly about 50,000 light years from the center of the galaxy, and then a ring of stars appears at about 60,000 light years from the center,” said Xu. “What we see now is that this apparent ring is actually a ripple in the disk. And it may well be that there are more ripples further out which we have not yet seen.”

In some aspects, figuring out the parameters of the Milky Way galaxy is even more difficult than figuring out those of other galaxies – because we are from the inside, and our point of view is rather limited.

“Extending our knowledge of our galaxy’s structure is fundamentally important,” said Glen Langston, NSF program manager. “The NSF is proud to support their effort to map the shape of our galaxy beyond previously unknown limits.”

Study Abstract.

Our Galaxy Might Be a Huge Wormhole

Based on latest evidence and calculations, our entire galaxy, the Milky Way, might be a a huge wormhole, stable and navigable. Astrophysicists combined the equations from general relativity with a distribution of dark matter to reach this conclusion

Our Galaxy… a Wormhole?

Our galaxy might be a huge wormhole, new research indicates. Image credits: Davide and Paolo Salucci

A wormhole is a hypothetical feature that is fundamentally a shortcut through spacetime. A wormhole is much like a tunnel with two ends, each with very different locations in spacetime. So how could our galaxy just be one big tunnel? The answer is strictly connected to dark matter, one of the greatest mysteries in the Universe.

“If we combine the map of the dark matter in the Milky Way with the most recent Big Bang model to explain the universe and we hypothesize the existence of space-time tunnels, what we get is that our galaxy could really contain one of these tunnels, and that the tunnel could even be the size of the galaxy itself,” explains Paolo Salucci, astrophysicist of the International School for Advanced Studies (SISSA) of Trieste and a dark matter expert.

Simulation of a wormhole:


Dark matter accounts for most of the matter in the entire universe, but we can’t see it with any of our instruments. it neither emits nor absorbs light or other electromagnetic radiation at any significant level and is generally believed to simply not react with light. According to recent measurements, normal matter (everything we see, including planets, stars, galaxies) accounts for less than 5% in the mass of the Universe, with 26.8% dark matter, 68.3% dark energy.

“But there’s more”, Salucci continues. “We could even travel through this tunnel, since, based on our calculations, it could be navigable. Just like the one we’ve all seen in the recent film ‘Interstellar’.” Salucci is among the authors of the paper recently published in Annals of Physics.

Dark Matter – the Stargate

We don’t know yet – but we’re working on it. Image via The Times.

So basically, our galaxy could be one big Universal travel tunnel. Even though among the general public, wormholes gained popularity mostly through sci-fi books or series (like Stargate or Intestellar), astrophysicists have carefully considered this option for years. Still, when dealing with such complex issues, it’s best to take things with a grain of salt; even the scientists working on this theory underline the fact that it’s still just a theoretical possibility.

“Obviously we’re not claiming that our galaxy is definitely a wormhole, but simply that, according to theoretical models, this hypothesis is a possibility.” Can it ever be tested experimentally? “In principle, we could test it by comparing two galaxies — our galaxy and another, very close one like, for example, the Magellanic Cloud, but we are still very far from any actual possibility of making such a comparison.”

Aside for revealing an extremely surprising conclusion about our galaxy, this study sheds a bit more light on what dark matter really is. Among the approaches trying to explain dark matter, some have proposed the existence of a particle, the neutralino. However, nothing at CERN or other any other particle accelerators have found any indication of such a particle existing. There are also other theories, but none of them have concrete evidence backing them up.

“[..]perhaps it’s time for scientists to take this issue ‘seriously’,” concludes Salucci. “Dark matter may be ‘another dimension’, perhaps even a major galactic transport system. In any case, we really need to start asking ourselves what it is.”

Journal Reference:

  1. Farook Rahaman, P. Salucci, P.K.F. Kuhfittig, Saibal Ray, Mosiur Rahaman.Possible existence of wormholes in the central regions of halos. Annals of Physics, 2014; 350: 561 DOI: 10.1016/j.aop.2014.08.003

 

The Laniakea Supercluster shown its equatorial plane. Image: CEA/Saclay, France

Astronomers map the Supercluster the Milky Way belongs to

The Laniakea Supercluster shown its equatorial plane. Image: CEA/Saclay, France

The Laniakea Supercluster shown its equatorial plane. Image: CEA/Saclay, France

Our sun is but a tiny speck of light among billions, part of the spiral galaxy we familiarly call the Milky Way. That in itself makes us puny humans feel extremely humble, but things get really out of proportion when you zoom out. Galaxies on their own turn congregate in the hundreds or even thousands, bound together by gravity to form a structure called galaxy clusters. These clusters can yet again cluster to form a mega structure astronomers typically refer to as a supercluster. Now, a team of international astronomers led by researchers at University of Hawaii at Manoa have mapped out the contour of the supercluster the Milky Way belongs to called “Laniakea” (Hawaiian for “immense sky”).

The astronomers used the National Science Foundation’s (NSF’s) Green Bank Telescope (GBT), in conjunction with other radio telescopes dotted around the planet to map out the peculiar velocity of the other galaxies that surround the Milky Way. This allowed them to define a contour for Laniakea, which is 500 million light-years in diameter and contains an incredible one hundred million billion suns extending across 100,000 galaxies.

“We have finally established the contours that define the supercluster of galaxies we can call home,” said R. Brent Tully, an astronomer at the University of Hawaii at Manoa. “This is not unlike finding out for the first time that your hometown is actually part of much larger country that borders other nations.”

The Laniakea Supercluster is held together by a large flat gravitational basin with a domain of attraction that spreads across the entire Supercluster.

Next, the researchers plan on translating the mapped velocities into three-dimensional space to come to a better understanding of how the large-scale cosmos works and white kind of influence Superclusters have in the universe. Astronomers are also interested in what they call the Great Attractor – a localized concentration of mass tens of thousands times that of the Milky Way which has a powerful influence on the inward motion clusters have within the Laniakea Supercluster.

Findings appeared in the journal Nature.

A star like our Sun is shown with an orbiting planet in the foreground in this artist's impression. Image credit: Illustration by Gabriel Perez Diaz, Instituto de Astrofisica de Canarias (MultiMedia Service)

Astronomers find the sun’s first sibling: a star made of the same stuff

A star like our Sun is shown with an orbiting planet in the foreground in this artist's impression. Image credit: Illustration by Gabriel Perez Diaz, Instituto de Astrofisica de Canarias (MultiMedia Service)

A star like our Sun is shown with an orbiting planet in the foreground in this artist’s impression. Image credit: Illustration by Gabriel Perez Diaz, Instituto de Astrofisica de Canarias (MultiMedia Service)

In what’s considered the first find out of a slew to follow, a team of astronomers have identified a star that originated out of the same matter as our own sun. In lack of a better analogy, the two are siblings and probably share many more sisters. Apart from telling us where in the galaxy our solar system first formed some 4.3 billion years ago, by finding and studying more of the sun’s siblings, certain secrets might become unraveled, even those pertaining to the origin of life.

Made from the same star stuff

From studies of other stars which astronomers can see in many different stages of their ‘life cycle’, it seems pretty convincing from the data that the sun must have started out as a large collapsing cloud of gas and dust inside some ancient interstellar cloud. This cloud was ‘polluted’ by a supernova several million years before the collapse phase ended, because we see certain isotopes of aluminum which could not have been a part of this cloud for very long unless they had been implanted by such an event.

The cloud collapsed for millions of years until it formed a rotating disk with a large central bulge. Out of the disk would eventually form the planets, and out of this central bulge where most of the mass wound up, formed the sun. We see such rotating disks of gas around many infant stars embedded in nebulae so this has confirmed this basic picture during the last 15 years or so. So this is where the sun comes from, but a more interesting question may be where does the gas and dust that initially comprised it came from?

The first sister of many

star_Stuff

The star is not visible to the unaided eye but easily can be seen with low-power binoculars, not far from the bright star Vega. Image credit: Ivan Ramirez/Tim Jones/McDonald Observatory

How and where the sun formed exactly and even how life in the solar system eventually appeared might be answered by this question and a  first step is identifying other stars made from the same original matter as our sun. Ivan Ramirez of The University of Texas and colleagues have for the first time identified such a sibling star after shifting through 30 possible candidates found by several groups around the world looking for stars in the Sun’s family. The candidates where carefully surveyed using the Harlan J. Smith Telescope at McDonald Observatory, while high-resolution spectroscopy was employed to get a deep understanding of the stars’ chemical make-up.

[RELATED] Most Earth-like planet orbiting around sun-like star: extraterrestrial life likely

Besides chemical analysis, the team of astronomers also mapped out each of the stars’ orbits around the center of the Milky Way. Data from these two important characteristics combined narrowed the field of candidates down to one: HD 162826 – a star 15 per cent more massive than the Sun, located 110 light-years away in the constellation Hercules.

Chances have it that this particular star had been studied by astronomers for at least 15 years so we’ve got a wealth of data at our disposal which can be used to characterize the star and its planetary system. For one, from what astronomers can tell, the star can’t possibly host any gas giant like Jupiter, and a small terrestrial planet might orbit it, although nobody’s entirely sure yet.

“We want to know where we were born,” Ramirez said. “If we can figure out in what part of the galaxy the Sun formed, we can constrain conditions on the early solar system. That could help us understand why we are here.”

Ramirez and colleagues’ ultimate goal is that of using data from this first sibling and those sure to follow in order to create a cook-book; a guideline that will narrow down future candidates and help find those stars that originated from the same material as the sun. This will definitely come most in handy once projects like the massive Gaia, a European Space Agency mission to create the largest and most precise 3-D map of the Milky Way, which includes accurate distances and proper motions for a billion stars. For instance, the team has found that a rather solid indicators the elements barium and yttrium, whose concentrations vary very much from star to star depending on where these were formed.

Star surveyor Gaia enters its operational orbit

The European Space Agency‘s billion-dollar star surveyor ‘Gaia’ is now in its operational orbit around a gravitationally stable virtual point in space, at about 1.5 million km from Earth.

Gaia has been traveling to reach that point since December 19, following a spectacular launch from Europe’s Spaceport in Kourou, French Guiana. Last night, the surveyor performed the last critical maneuvers, and everything went just fine.

“Entering orbit around L2 is a rather complex endeavour, achieved by firing Gaia’s thrusters in such a way as to push the spacecraft in the desired direction whilst keeping the Sun away from the delicate science instruments,” describes David Milligan, Gaia spacecraft operations manager. After a beautiful launch from Kourou last month, we are very happy to now have reached our destination, and we are looking forward to starting our science operations in the coming months,” says Giuseppe Sarri, ESA’s Gaia project manager.

Gaia’s mission is to make very accurate observations of approximately one billion stars, charting not only their precise positions and motions, but also their temperatures, luminosities and even compositions. The result will be the largest map of the Milky Way done so far, with a huge amount of data which will allow astronomers to better understand the formation and evolution of our galaxy.

Gaia will observe each star an average of 70 times over the five-year mission, and it’s estimated that the data archive will reach 1 million gigabytes – the equivalent of approximately 200.000 DVDs. The monumental task of processing and interpreting the data will fall on the back of more than 400 individuals at scientific institutes across Europe.

“Our Gaia discovery machine will keep us busy throughout the mission, with the final results coming only after the five years of data have been analysed. But it will be well worth the wait, ultimately giving us a new view of our cosmic neighbourhood and its history,” says Timo Prusti, ESA’s Gaia project scientist.

Via ESA.

A 12-year study of massive stars has reaffirmed that our Galaxy has four spiral arms, following years of debate sparked by images taken by NASA’s Spitzer Space Telescope that only showed two arms. (c) University of Leeds

The Milky Way grows back two spiral arms

There has been a debate over the number of spiral arms the Milky Way galaxies has, due to mixed results in the past. For years, it was believed the Milky Way had four spiral arms, but in 2008 readings from the Spitzer Space Telescope suggested it actually had only two. Wouldn’t you know it, a new study that looked at young and massive star found that the Milky Way must have four arms.

Four arms, not two, survey suggests

From our perspective, it’s impossible to simply pan out and have a view of how the Milky Way looks like. Most certainly you’ve seen quite a couple of beautiful renditions of the Milky Way – most of which with two spiral arms – however these are all artist impressions. Simple computer generated graphics based on scientists’ description. Raw data is everything we have at the moment to interpret the size, shape and structure of our very own galaxy.

A 12-year study of massive stars has reaffirmed that our Galaxy has four spiral arms, following years of debate sparked by images taken by NASA’s Spitzer Space Telescope that only showed two arms. (c) University of Leeds

A 12-year study of massive stars has reaffirmed that our Galaxy has four spiral arms, following years of debate sparked by images taken by NASA’s Spitzer Space Telescope that only showed two arms. (c) University of Leeds

James Urquhart at the Max Planck Institute for Radio Astronomy in Bonn, Germany and team recently performed a survey of massive stars from the Milky Way. Since massive stars fly high and die fast  – they only last for some 10 million years or so – meaning that they are only found in the arms in which they formed, which could explain the discrepancy in the number of galactic arms that different research teams have claimed. The controversial 2008 Spitzer survey analyzed some 110 million stars, most of which were cooler, lower-mass stars – stars like our sun. These are much more numerous than the massive and bright stars targeted by the present study.

 “It’s exciting that we are able to use the distribution of young massive stars to probe the structure of the Milky Way and match the most intense region of star formation with a model with four spiral arms,” said Urquhart.

Several radio telescopes in Australia, the U.S. and China were used to observe about 1,650 massive stars over the course of 12 years. Scientists calculated the distances and luminosities between them and came up with a spatial distribution that suggests a four spiral arm galaxy.

“Star formation researchers, like me, grew up with the idea that our galaxy has four spiral arms. It’s great that we have been able to reaffirm that picture,” said astronomer Melvin Hoare at the University of Leeds, a co-author of the research paper.

Findings were reported in a paper published in the Monthly Notices of the Royal Astronomical Society.