Tag Archives: alpha-centauri

Researchers find new gas giant planet orbiting around b Centauri

Using direct telescope imaging, a group of researchers has identified a gas-giant planet orbiting the high-mass binary star system of b Centauri — the closest solar system to Earth. The finding suggests that planets can reside in much more massive stellar systems than was previously expected. 

Image credit: Wikipedia Commons.

According to Markus Janson, lead author of the new study, many researchers believed that planet formation should be impossible around such stars. The reason is that massive stars emit a lot UV and X-ray radiation, so any dust or gas around them should dissipate quickly, leaving very little time for planets to form from that material.

“However, history teaches us those theoretical expectations about where exoplanets can or cannot reside are often not reliable,” Janson argued. The first exoplanet ever detected, the Jupiter 51 Peg b, is a good example of this. The discovery was surprising as people didn’t think it was possible for gas giant planets to orbit so close to stars.

With this in mind, Janson and his team decided to start the so-called BEAST survey, looking for planets around a class of massive stars called “B-type” stars. The survey uses a technique called high-contrast imaging to detect the faint light of a planet next to the much brighter light of the star it orbits. They are now observing 85 of the B-type stars, and the survey has already made some interesting discoveries.

A new finding

The researchers observed a gas-giant planet between March 2019 and April 2021, using the SPHERE exoplanet imager which is installed on the European Southern Observatory’s Very Large Telescope in Paranal, Chile. The planet that they found orbits the stars of the binary system at 560 times the distance between Earth and the Sun. For comparison, Pluto lies at 39 times the distance between the Earth and the Sun.

“This shows that planets can in fact survive around massive stars, which is an important realization, implying that we have to think deeply about how it might have formed. We can also measure orbital motion for the planet, and can conclude that its orbit is relatively circular, which is also interesting with respect to its formation,” Janson said.

For the researchers, it’s also significant that the parent star, b Centauri, is easily visible to the naked eye. This is highly unusual for an exoplanet host star, since most exoplanets to date are found in systems that are modestly bright and far away, and therefore only visible in a telescope. The direct visibility of b Centauri connects it to the general public. 

The project was delayed for over a year because the telescope in Chile used for the BEAST survey was shut down in the Spring of 2020 because of the pandemic, and was kept closed over the summer – the period in which BEAST targets can be observed. But the telescope was restarted this year, and the researchers have a lot of data they plan to keep on working on next year.

The study was published in the journal Nature.

Sprite tiny probe.

This space probe is so small you could lose it in your backpack — and it just got launched into space

If at first you don’t succeed — go smaller. Breakthrough Starshot, an initiative that aims to send spacecraft to neighboring star systems, has launched half a dozen teeny tiny probes named Sprites to see test their minute electronics against outer space

Sprite tiny probe.

Image credits Breakthrough Starshot.

We’re understandably quite excited as a species for the day we finally reach some place that isn’t ‘here’. In cosmic terms, that would be Alpha Centauri, a trio of stars that are our closest neighbors. But there’s a problem: since we’re talking in cosmic terms, it would take tens, possibly even hundreds of thousands of years for a ship blasting with the full might of our current propulsion tech to reach Alpha Centauri. Which just won’t do.

Baby ships

Breakthrough Starshot is trying to work around that issue by capitalizing on a technology emerging in the last 15 or so years to reach a significant fraction of light speed: light-powered space travel. What this basically entails is for a hugely powerful Earth-borne laser to shine on a craft and thus provide thrust. It’s not a lot of thrust, granted, since you’re pushing stuff with light, but on the upside it’ll allow you to go pretty fast eventually.

Here’s where the Sprites come in. Each Sprite represents a prototype of the crafts Starshot wants to send a-knocking to Alpha Centauri. And they’re really, really tiny. The whole probe is built on a single 3,5 cm (1,37 inch) square circuit board and weighs in at a hefty four grams (0,14 ounces). Each packs a solar panel, radio, thermometer, magnetometer for compass capabilities and gyroscope for sensing rotation, and costs about ten dollars to make.

“We’re talking about launching things that are a thousand times lighter than any previous spacecraft,” says Avi Loeb, an astrophysicist at Harvard University who is part of the committee advising the initiative.

Fit some lightsails on them and these bite-sized crafts can reach up to 160 million km (100 million miles) per hour, potentially reaching Alpha Centauri in about 20 years from launch. They won’t have a human crew, sure, but will be perfectly capable of beaming back pictures and other data from the planets there.

For now, the probes were launched into space to see if they’ll survive in the cold, harsh conditions up there. They hitched a ride on a low Earth orbit on two satellites, Max Valier and Venta-1. Each satellite has a Sprite permanently attached to its outer casing, and the Max Valier holds a further four it can deploy to space. As of August 10, however, ground control hasn’t been able to deploy these four Sprites, and only one of the two permanently attached ones (probably the one on Venta-1) is still in radio contact.

Comms problems aside, the Sprites seem to hold out fine up to now. The team plans to add more tools including cameras and actuators offer more control to the Sprites before sending the next generation of “StarChip” probes on their way to Alpha Centauri, and to shift communications to a laser-based system rather than the current radio one.

Habitable planet in Tau Ceti system

Another Earth could be just 12 light years away

Astronomers have discovered five planets orbiting Tau Ceti, the closest single star that resembles our Sun in terms of temperature and luminosity.

Finding our cosmic neighbors

Habitable planet in Tau Ceti system

An artist’s depiction of a planet in the Tau Ceti system.

If the planets are indeed there and no error was involved in the study, then there’s a good chance one of them is the right distance from the star to sport adequate temperatures, liquid oceans – and even life. But don’t pack your bags just yet – there is still some skepticism surrounding the find.

Tau Ceti has about 78% of the Sun’s mass, and it is “just” 3 times as far as our closest neighbor – Alpha Centauri; however, unlike Alpha Centauri, who also has a G-type star and even a planet that could host life, Tau Ceti is single – there is no other star that could yank planets away.

Earth, water and fire

All of the five planets are closer than to Tau Ceti than the Earth is to the Sun, but that’s actually a good thing – since the star only emits 45% as much light and warmth as the sun, the planets have to be significantly closer to harbor life. The five candidates for life are relatively small, but still bigger than the Earth – with masses ranging from 2 to 6.6 times that of Earth.

The Earth is a rocky planet – also known as terrestrial or telluric planet; the best candidate for life in the system of Tau Ceti, which completes one lap around its star in 168 days, however, is unlikely to be a rocky planet.

“It is impossible to tell the composition, but I do not consider this particular planet to be very likely to have a rocky surface,” lead author Mikko Tuomi, of the University of Hertfordshire in England, explained. “It might be a ‘water world,’ but at the moment it’s anybody’s guess.”

An ocean planet (also termed a waterworld) is a type of planet whose surface is completely covered with an ocean of water – but don’t despair: life is at least just as likely to appear on those worlds. However, researchers are still awaiting the confirmation for the results.

Via Space.com

Earth-sized lava world found in Alpha Centaury – closest find yet

The search for other planets gets more and more exciting and fruitful, and now, researchers have found an exoplanet which lies truly close to us – in cosmic terms.

Alpha Centauri

Alpha Centauri is the closest solar system to our own, at only 4 light years away, so finding an Earth-sized planet there really is a big thing, and it shows that the myriad of writers inspired weren’t really far away from the truth. However, don’t get any hopes up – the planet is closer to its star than Mercury is to the Sun, so it’s basically just a scorched and barren rock. To make things even worse, despite of its astronomic proximity to Earth which sparks dreams of interstellar travel, we are nowhere near able to travel to it at the moment.

Alpha Centauri seems to be a single star to the unaided eye, but it is actually a binary system, with Alpha Centauri A and B – both comparable in terms of size with our Sun; the newfound planet orbits Alpha Centauri B.

Finding planets

The planet, which is the closest we’re ever going to find, was observed using a technique that monitors a star for a subtle back-and-forth ‘wobble’ in its motion as seen from Earth, caused by a gravitational effect. Neither the star nor the planet are unusual in any way, aside for their proximity to Earth. However, even though it isn’t habitable according to what we know now, an Earth twin could also be hiding in the area, says Ralph McNutt, a planetary scientist at Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.

Geoff Marcy, an astronomer at the University of California, Berkeley, who leads another ground-based search effort, says that the discovery should bolster calls for a space-based tele­scope that could image any other planets near α Centauri B, if they have large enough orbits.

Source
The study was published in Nature