Tag Archives: eso

RCW 38.

The constellation Vela explodes with color (and new suns) in ESO-captured snaps

The European Southern Observatory just published a breathtaking image of a nearby star nursery.

RCW 38.

Star cluster RCW 38.
Image credits ESO / K. Muzic.

Earlier today, we’ve talked about the first colors complex-ish life created — it was a story of algae, fossils, and pink. Moving on from this daring display by early life, however, I thought we’d seize the occasion to look at what colors accompany birth in the other direction — up in space.

Our eyes can’t peer that far out, but, luckily for us, the European Southern Observatory (ESO) can. Using the HWAK-I (High Acuity Wide field K-band Imager) infrared imager mounted on the Very Large Telescope (VTL) in Chile, the ESO captured some spectacular shots of stars being born in the Vela constellation.

Ashes to ashes, dust to stars

Vela constellation, RCW 38.

RCW 38 in the constellation of Vela (The Sails). The map shows most of the stars visible to the unaided eye under good conditions.
Image credits ESO / IAU / Sky & Telescope.

The image depicts the star cluster RCW 38 as seen in infrared. ESO chose this bit of the electromagnetic spectrum for their observations since infrared can see ‘through’ the clouds shrowding star nurseries such as RCW 38. The cluster itself contains hundreds of young, brightly hot, and quite massive stars. Even at the relatively short distance of 5500 light-years away, however, their (visible) light can’t peer through the vast bodies of dust surrounding the cluster.

The central area, seen as a bright blue region, houses numerous very young stars as well as a few protostars — ‘stars’ that are still forming. Observations by the Chandra X-ray Observatory revealed the presence of over 800 X-ray emitting young stellar objects in the cluster. You won’t be surprised to hear, then, that the area is drenched in radiation, making local gas clouds glow vividly. Cooler bodies of dust languishing in front of the cluster carry more subdued, darker hues of red and orange. The end result, a ‘colorful celestial landscape’ as ESO puts it, is quite the striking interplay of color and light.

This image was captured as part of a series of tests — a process known as science verification — for HAWK-I and GRAAL (the ground layer adaptive optics module of the VLT). These tests are performed to ensure newly-commisioned instruments work as intended and include a set of test observations that verify and demonstrate the capabilities of the new instrument.

RCW 38 optic.

Star cluster RCW 38 in the visible spectrum.
Image credits ESO – Digitized Sky Survey 2 / Davide De Martin.

Previous images of this region — snapped in the visible spectrum — show a very different sight. Optical images appear almost devoid of stars in comparison with those taken in the infrared spectrum due to dust obscuring the view.

Peering through dense bodies such as dust clouds or nebulae is actually one of the HWAK-I’s main roles. The device also projects four laser beams out into the night sky to use as artificial reference stars — used to correct for any atmospheric turbulence, which can bend incoming light — to increase the quality of the final image.

This deep image shows the region of the sky around the quasar HE0109-3518. The quasar is labelled with a red circle near the centre of the image. The energetic radiation of the quasar makes dark galaxies glow, helping astronomers to understand the obscure early stages of galaxy formation. The faint images of the glow from 12 dark galaxies are labelled with blue circles Click for ZOOM. (C) ESO

First evidence of dark galaxies from the early Universe spotted

An international team of astronomers may have come across the first sound evidence testifying the existence of dark galaxies – cosmic bodies from the early Universe long theorized by scientists in the past, but never before confirmed until now.

Dark galaxies are small, gas-rich galaxies that are very inefficient at forming stars themselves. Their name comes from the fact that they’re void of stars, thus no light is emitted, making them theoretically invisible. Scientists consider dark galaxies to have played a major role in star-rich galaxy formation during the early Universe expansion, feeding neighboring galaxies with precious gas required to birth stars.

Since dark galaxies don’t emit any light, confirming their existence has been always extremely difficult for scientists attempting such a feat. Previous studies of small absorption dips in the spectra of background light sources were thought to have hinted at dark galaxies, but this newly presented research is the first to provide rather tantalizing proof.

Using the European Southern Observatory’s Very Large Telescope (VLT) in northern Chile, the researchers saw the extremely faint fluorescent glow of the dark galaxies.

“Our approach to the problem of detecting a dark galaxy was simply to shine a bright light on it,” says Simon Lilly of ETH Zurich.

“We searched for the fluorescent glow of the gas in dark galaxies when they are illuminated by the ultraviolet light from a nearby and very bright quasar. The light from the quasar makes the dark galaxies light up in a process similar to how white clothes are illuminated by ultraviolet lamps in a night club.”

This deep image shows the region of the sky around the quasar HE0109-3518. The quasar is labelled with a red circle near the centre of the image. The energetic radiation of the quasar makes dark galaxies glow, helping astronomers to understand the obscure early stages of galaxy formation. The faint images of the glow from 12 dark galaxies are labelled with blue circles  Click for ZOOM. (C) ESO

This deep image shows the region of the sky around the quasar HE0109-3518. The quasar is labelled with a red circle near the centre of the image. The energetic radiation of the quasar makes dark galaxies glow, helping astronomers to understand the obscure early stages of galaxy formation. The faint images of the glow from 12 dark galaxies are labelled with blue circles Click for ZOOM. (C) ESO

The telescope was directed towards a patch of the sky, around the bright quasar HE 0109-3518, where it mapped the region and looked for ultraviolet light released by hydrogen gas when subjected to radiation. Quasars are the brightest and most energetic objects in the Universe. The exposure time was enormous, but in the end it paid out for the astronomers.

“After several years of attempts to detect fluorescent emission from dark galaxies, our results demonstrate the potential of our method to discover and study these fascinating and previously invisible objects,” study lead author Sebastiano Cantalupo, from the University of California, Santa Cruz, said in a statement.

Their initial round of data returned 100 possible gaseous objects which lie within a few million light-years of the quasar. Eliminating objects where the emission might have been powered by internal star-formation in neighborliness galaxies, the team of researchers narrowed the list down to 12.

Also, the researchers were able to determine some of the dark galaxies’ properties. They speculate the mass of the gas in dark galaxies is about one billion times that of the sun, and that they’re 100 times less efficient at forming stars than most galaxies of the time. Their exact composition hasn’t been determined yet, since there’s no conclusive way of determining it. However, theoretically they’re composed of hydrogen, dust and dark matter.

“Our observations with the VLT have provided evidence for the existence of compact and isolated dark clouds,” Cantalupo said. “With this study, we’ve made a crucial step towards revealing and understanding the obscure early stages of galaxy formation and how galaxies acquired their gas.”

This research was presented in a paper entitled “Detection of dark galaxies and circum-galactic filaments fluorescently illuminated by a quasar at z=2.4”, by Cantalupo et al. to appear in Monthly Notices of the Royal Astronomical Society.

source: ESO

Brilliant Very Large Telescope image captures the tumult of a starbirth

The process of starbirth is a beautiful yet violent one; newborn stars spew material into the surrounding gas, creating surreal photos, often with glowing bulbs, arcs or streaks. This kind of picture is always spectacular, and ESO’s Very Large Telescope (VLT) managed to catch quite a few of them on camera, delighting astronomers and the general public as well. This new image, released today, was taken in NGC 6729, a nearby star-forming region in the constellation Corona Australis.

This area is a stellar nursery, one of the ones which are closest to us, and therefore one of the most studied. This image was selected from the ESO archive by Sergey Stepanenko, as part of the Hidden Treasures competition. The 2010 competition gave amateur astronomers the opportunity to search through ESO’s archives in the hope that a few gems that need polishing would be found, and Stepanenko’s picture rated third, as Igor Chelakin claimed both the first and second prize, with some absolutely stunning pictures (here and here).

The first stages of star development cannot be observed in visible light telescopes, because they eject so much dust, but although you cannot see them, you can see the havoc they wreaked.

In this picture, you can easily see the Herbig Haro objects showcasing the two probable lines of material ejection. The different colours reflect different star forming conditions, for example glowing hydrogen is orange, ionized sulphur is blue, and understanding the processes that led to this image can help astronomers unravel what is happening in this hectic part of space.

Pictures via ESO