Starship Asterisk*

Image Credit: Zdeněk Bardon/ESO

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From the long eastward shadows of the telescopes in this Picture of the Week we can see that it’s almost the beginning of a long night shift of stargazing for the telescopes at ESO’s La Silla Observatory. In the foreground of this picture is the BlackGEM array, designed to hunt for the visible light of gravitational wave sources. If you then follow the road up to the summit of La Silla you will pass several ESO telescopes including the 1-metre Schmidt telescope and the New Technology Telescope, until you finally reach the 3.6-metre telescope at the top, home to the HARPS planet hunter.

La Silla mountain is ideally situated for an observatory as its isolated location means there is very little light pollution. It is also in Chile’s extremely dry Atacama desert at an altitude of 2400 metres, meaning there’s hardly ever a cloud in the sky and almost every day boasts clear blue skies as can be seen in this picture.

A spiral galaxy is seen edge-on and tilted at an angle. The body of the galaxy is blue and obscured by threads of dark red dust, and it is surrounded by a pale glow. Three stars with prominent cross-shaped diffraction spikes are very bright in the foreground. The background is dark and sparsely-covered in small stars.

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Image Credit: ESA/Hubble & NASA, C. Kilpatrick

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The somewhat amorphous spiral galaxy UGC 2890 appears side-on in this image from the NASA/ESA Hubble Space Telescope, with bright foreground stars studding the image. This galaxy lies around 30 million light-years away in the constellation Camelopardalis. In 2009 astronomers spotted a catastrophically powerful supernova explosion in UGC 2890. While the supernova itself has long since faded from view, Hubble recently took a break from its regular observing schedule to inspect the aftermath of this explosive event.

A Type II supernova is a spectacularly energetic explosion that marks the violent death of a massive star. As it runs out of the elements necessary to fuel nuclear fusion, the core of a massive star flickers out and stops producing energy. With nothing to support the crushing force of gravity, the core of the star shrinks and then suddenly implodes, leaving the star’s outer layers to collapse inwards and rebound out into space as a supernova explosion.

This observation is one of many Hubble investigations of Type II supernovae. Astronomers turned to Hubble’s Advanced Camera for Surveys to explore the surroundings of Type II supernovae in the hope of discovering the ages and masses of stars in the neighbourhood. This will reveal insights into the types of stars that eventually create Type II supernovae, as well as revealing any stellar survivors of colossal supernova explosions.

starsurfer wrote: ↑Mon Apr 03, 2023 10:34 pm Sh2-240, G179.0+2.6 and M37
https://www.astrobin.com/j0p1vg/
Copyright: Rolf Dietrich

Click to view full size image

The emission nebula north of Sh2-240 is Du 77 while Sh2-242 is the small HII region below and to the left. The planetary nebula associated with M37 can faintly be seen in the full resolution image.

The beautiful Spaghetti Nebula has a real rarity in its vicinity, the SNR 179.0+2.6
It is a very old SNR that mainly emits OIII.
Its diameter about 70 arcmin in our apperent view.
I discovered the object by accident on the net:
Optical emission associated with the Galactic supernova remnant G179.0+2.6 | Monthly Notices of the Royal Astronomical Society | Oxford Academic (oup.com)
The SNR 179.0+2.6 is extremely faint.
In my Bortle 4-5 Homeplace it could hardly be seen even after a long exposure time with the 4nm OIII filter.
So I had to drive with batteries to a rural area and take images in the open countryside. SQM at peaks 20.9 arcsec².
I hope you like it.

Image Credit: Zdeněk Bardon/ESO

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Don’t worry, no planets were harmed in the making of this Picture of the Week! The powerful laser beams seen here are installed in one of the four 8.2-m telescopes of ESO’s Very Large Telescope (VLT) in Chile. They allow astronomers to obtain very sharp images of the cosmos by correcting the blur caused by turbulence in the atmosphere, but how?

The lasers are tuned to a very specific colour that excites sodium atoms floating 90 km above the ground, making them glow. This creates artificial “stars” high up in the sky, whose rapid twinkling is monitored in real time by special sensors. Then, instructions are sent to the telescope’s deformable secondary mirror, which quickly reshapes itself to counteract the atmospheric distortion. And all of this happens at millisecond speeds!

This technique, known as adaptive optics, can also use real stars as a reference to measure the turbulence. But there isn’t always a bright enough star right next to the object one wants to observe, and this is when artificial laser stars come in handy.

How do the lasers themselves work, and what other astronomical applications do they have? Find out in this ESO blog post.

A spiral galaxy in the centre is tilted almost edge-on. The bright core and spiral arms can just be seen from the top. A slight glow surrounds it. Below, strands made of bright blue patches trail down like tentacles. On the left it is just touched by a second, faint and dim galaxy. The background is very dark, with only a few other stars and tiny galaxies visible.

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Image Credit: ESA/Hubble & NASA, M. Gullieuszik and the GASP team

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Here we see JO204, a ‘jellyfish galaxy’ so named for the bright tendrils of gas that appear in this image to be drifting lazily below JO204’s bright central bulk. The galaxy lies almost 600 million light-years away in the constellation Sextans. This image was captured by the NASA/ESA Hubble Space Telescope, and it is the third of a series of Pictures of the Week featuring jellyfish galaxies. This series of images is possible thanks to a survey in which observations were made of six of these fascinating galaxies, including JO204. This survey was performed with the intention of better understanding star formation under extreme conditions.

Given the dreamy appearance of this image, it would be understandable to wonder why jellyfish galaxies should be such a crucible for star formation. The answer is that — as is often the case with astronomy — first appearances can be deceiving. Whilst the delicate ribbons of gas beneath JO204 may look like floating jellyfish tentacles, they are in fact the outcome of an intense astronomical process known as ram pressure stripping.

Ram pressure is a particular type of pressure exerted on a body when it moves relative to a fluid. An intuitive example is the sensation of pressure you experience when you are standing in an intense gust of wind — the wind is a moving fluid, and your body feels pressure from it. An extension of this analogy is that your body will remain whole and coherent, but the more loosely bound things — like your hair and your clothes — will flap in the wind. The same is true for jellyfish galaxies. They experience ram pressure because of their movement against the intergalactic medium that fills the spaces between galaxies in a galaxy cluster. The galaxies experience intense pressure from that movement, and as a result their more loosely bound gas is stripped away. This gas is mostly the colder and denser gas in the galaxy — gas which, when stirred and compressed by the ram pressure, collapses and forms new stars in the jellyfish’s beautiful tendrils.

• Astrophysical Journal 945(1):54 (2023 Mar 01) DOI: 10.3847/1538-4357/acb59b
• arXiv > astro-ph > arXiv:2301.08279 > 19 Jan 2023

• arXiv > astro-ph > arXiv:2302.10615 > 21 Feb 2023

Image Credit: Gemini Observatory/NOIRLab/NSF/AURA/T. Slovinský

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The silver dome of the Gemini North telescope, one half of the International Gemini Observatory, operated by NSF’s NOIRLab, catches the setting Sun, caught between the red-hued earth of the Maunakea volcano and an inky-blue sky. The scale of astronomical infrastructure can be difficult to grasp from images, particularly when telescopes are located in vast landscapes under wide skies. However, if you look closely the staircases winding up the side of Gemini North are visible — revealing the true size of this telescope. The dome of Gemini North — and that of its twin, Gemini South in Chile — is around 46 meters (150 feet) across, meaning that the two telescopes side-by-side would almost fit in an entire soccer field!

Ann wrote: ↑Sun Apr 09, 2023 4:41 am

starsurfer wrote: ↑Mon Apr 03, 2023 10:34 pm Sh2-240, G179.0+2.6 and M37
https://www.astrobin.com/j0p1vg/
Copyright: Rolf Dietrich

Click to view full size image

The emission nebula north of Sh2-240 is Du 77 while Sh2-242 is the small HII region below and to the left. The planetary nebula associated with M37 can faintly be seen in the full resolution image.

I found the caption unhelpful and went to Rolf Dietrich's own homepage to learn more. This is what he wrote about his image:

The beautiful Spaghetti Nebula has a real rarity in its vicinity, the SNR 179.0+2.6
It is a very old SNR that mainly emits OIII.
Its diameter about 70 arcmin in our apperent view.
I discovered the object by accident on the net:
Optical emission associated with the Galactic supernova remnant G179.0+2.6 | Monthly Notices of the Royal Astronomical Society | Oxford Academic (oup.com)
The SNR 179.0+2.6 is extremely faint.
In my Bortle 4-5 Homeplace it could hardly be seen even after a long exposure time with the 4nm OIII filter.
So I had to drive with batteries to a rural area and take images in the open countryside. SQM at peaks 20.9 arcsec².
I hope you like it.

So the large intricately shaped red and blue object is the well-known Spaghetti Nebula, but the real rarity is the blue object to the upper left of it. This object, SNR 179.0+2.6, is a very old and very faint supernova remnant that mainly emits OIII light. Rolf Dietrich may be the first person ever to photograph it.

Fascinating! I really wondered what that blue object was! Very well done, Rolf!

Ann

Click to view full size image 1 or image 2

V* V2423 Ori ~ Credits: ESO/Kirwan et al.

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This Picture of the Week shows the young stellar object 244-440 in the Orion Nebula observed with ESO’s Very Large Telescope (VLT) –– the sharpest image ever taken of this object. That wiggly magenta structure is a jet of matter launched close to the star, but why does it have that shape?

Very young stars are often surrounded by discs of material falling towards the star. Some of this material can be expelled into powerful jets perpendicularly to the disc. The S-shaped jet of 244-440 suggests that what lurks at the center of this object isn’t one but two stars orbiting each other. This orbital motion periodically changes the orientation of the jet, similar to a water sprinkler. Another possibility is that the strong radiation from the other stars in the Orion cloud could be altering the shape of the jet.

These observations, presented in a new paper led by Andrew Kirwan at Maynooth University in Ireland, were taken with the Multi Unit Spectroscopic Explorer (MUSE) instrument at ESO’s VLT in Chile. Red, green and blue colours show the distribution of iron, nitrogen and oxygen respectively. ...

• Astronomy & Astrophysics (forthcoming) DOI: 10.1051/0004-6361/202245428
• arXiv > astro-ph > arXiv:2303.13205 > 23 Mar 2023 (v1), 24 Mar 2023 (v2)

A large spiral galaxy. It has many narrow arms that are tightly-twisted in the centre, but at the ends they point out in different directions. The galaxy’s core glows brightly, while its disc is mostly faint, but with bright blue spots throughout the arms. A few smaller spiral galaxies at varying angles are visible in front, and it is surrounded by other tiny stars and galaxies, on a black background.

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Image Credits: ESA/Hubble & NASA, C. Kilpatrick, R. J. Foley

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The barred spiral galaxy UGC 678 takes centre stage in this image from the NASA/ESA Hubble Space Telescope. The spectacular galaxy lies around 260 million light-years from Earth in the constellation Pisces and is almost face on, allowing its lazily winding spiral arms to stretch across this image. In the foreground, a smaller edge-on galaxy seems to bisect the upper portion of UGC 678.

Just like humans, stars have a natural lifecycle; they are born, grow up, and eventually grow old and die. Studying this stellar life cycle — usually referred to as stellar evolution — is an important topic for astronomers. The ends of star lives can be marked by truly spectacular events, including titanic supernova explosions, the creation of unimaginably dense neutron stars, and even the birth of black holes. UGC 678 was recently found to be host to one of these events; in 2020 a robotic telescope scanning the night sky in search of dangerous asteroids discovered evidence of an enormous supernova explosion in the galaxy.

Two separate Hubble observations turned to UGC 678 to scour the galaxy in search of the aftermath of its supernova explosion. One team of astronomers used Hubble’s Advanced Camera for Surveys (ACS), and the other the Wide Field Camera 3 (WFC3), but both aimed to explore UGC 678 in the hope of unearthing clues to the identity of the star that produced the 2020 supernova.