Starship Asterisk*

Image Credit: ESA/Hubble & NASA, K. Larson et al

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Some galaxies are closer friends than others. While many live their own separate, solitary lives, others stray a little too close to a near neighbour and take their relationship to the next level.

The galaxy in this Picture of the Week, named NGC 6286, has done just that! Just out of frame lies its partner, NGC 6285. Together, the duo is named Arp 293 and they are interacting, their mutual gravitational attraction pulling wisps of gas and streams of dust from them, distorting their shapes, and gently smudging and blurring their appearances on the sky — to Earth-based observers, at least.

The NASA/ESA Hubble Space Telescope has viewed a number of interacting pairs. These can have distinctive, beautiful, and downright odd shapes, ranging from sheet music to a spaceship entering a sci-fi-esque wormhole, a bouquet of celestial blooms, and a penguin fiercely guarding its precious egg.

Arp 293 is located in the constellation of Draco (The Dragon), and lies over 250 million light-years from Earth.

Image Credit: ESO/Babak Tafreshi (TWAN)

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High up in the outskirts of the Chilean Atacama Desert, in the skies above ESO’s La Silla Observatory, a meteor blazes across the star-studded and dust-streaked Milky Way. This picturesque event had a silent, static onlooker, visible here to the left of the frame: the Swedish-ESO Submillimetre Telescope (SEST).

The SEST was built in 1987 on behalf of ESO and the Swedish Natural Science Research Council, and was decommissioned in 2003. For those 16 years it gazed up at some of the darkest and clearest skies in the world. At the time of construction, the 15-metre SEST was the only large telescope in the southern hemisphere designed for submillimetre astronomy.

While active, the SEST was used for a broad range of research, including observing the centre of the Milky Way, and studying our galaxy’s two satellites, the Magellanic Clouds. In 1995, SEST observations showed the Boomerang Nebula — a gas cloud formed by a dying star in the constellation of Centaurus (The Centaur) — to be the coldest known location in the Universe at only one degree warmer than absolute zero.

bystander wrote: ↑Fri Nov 22, 2019 4:37 pm

Ann wrote: ↑Fri Nov 22, 2019 7:59 am

starsurfer wrote: ↑Wed Nov 20, 2019 1:28 pm B30 region
http://buckeyestargazer.net/Pages/Nebulae/B30.php
Copyright: Joel Short
B30.jpg

Great picture! Starsurfer, do you know where this region is located? The designation, B30, tells me nothing.

If you click on the link, the image header says "Jewels in Orion", so I'm guessing somewhere in the Orion constellation.
Rollover the image on the linked page and many more identifiers pop up. Maybe they will help you find the region.

Ann wrote: ↑Fri Nov 22, 2019 7:59 am

starsurfer wrote: ↑Wed Nov 20, 2019 1:28 pm B30 region
http://buckeyestargazer.net/Pages/Nebulae/B30.php
Copyright: Joel Short
B30.jpg

Great picture! Starsurfer, do you know where this region is located? The designation, B30, tells me nothing.

starsurfer wrote: ↑Wed Nov 20, 2019 1:28 pm B30 region
http://buckeyestargazer.net/Pages/Nebulae/B30.php
Copyright: Joel Short
B30.jpg

A Spiral Snowflake (NGC 6814) ~ Credit: ESA/Hubble & NASA

This stunning composite Hubble photograph (credited to Judy Schmidt *; click for the full 2.6’ x 2.6’ view) reveals a nearby Seyfert galaxy, NGC 6814. How do we determine the distances to galaxies like this one? One approach is to use variable stars known as Cepheids. Cepheids have a direct relationship between their luminosity and pulsation period, so if we observe a sample of Cepheids in a galaxy, we can use their pulsations to infer the distance to that galaxy. A team of scientists led by Misty Bentz (Georgia State University) recently used Hubble imaging to identify 90 excellent Cepheid candidates in NGC 6814, allowing them to estimate a precise distance to the galaxy. They find it to be just a brief hop away (relatively speaking): roughly 71 million light-years. To learn more about the authors’ study, check out the original article below.


* The image is not Judy's (NGC 6814), but ESA Hubble's (potw1619a)

• Astrophysical Journal 885(2):161 (2019 Nov 10) DOI: 10.3847/1538-4357/ab48fb
• arXiv.org > astro-ph > arXiv:1910.00666 > 01 Oct 2019

bystander wrote: ↑Mon Nov 18, 2019 3:47 pm Perched on the Mountain Top
ESO Picture of the Week | 2019 Nov 18

Image Credit: ESO/Babak Tafreshi (TWAN)

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ESO’s astronomical facilities in Chile are hives of activity — or oases! — in the otherwise barren and arid landscape of the Atacama Desert. This hostile and hard-to-reach location may seem like an odd choice for construction, but the Atacama is one of the best sites in the world for astronomy. It has practically no cloud cover, a distinct lack of light pollution, and is the driest non-polar location in the world, receiving under two centimetres of rainfall every year!

Chile has hosted ESO’s telescopes since the 1960s, in observatories based at La Silla, Paranal, and Chajnantor Plateau. Shown here is the Visible and Infrared Survey Telescope for Astronomy (VISTA), situated at the Paranal Observatory.

Perched atop a mountain adjacent to Cerro Paranal, the home of the flagship Very Large Telescope (VLT), VISTA is the largest telescope in the world designed to survey the sky in near-infrared light (just beyond that visible to humans). The spectacular sights of the cosmos — including the notable streak of our home galaxy, the Milky Way, stretching across the top of the frame here — are more than enough to keep VISTA and its telescopic siblings busy.

Image Credit: ESA/Hubble & NASA, D. Rosario et al.

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For this Picture of the Week, the NASA/ESA Hubble Space Telescope turned its powerful eye towards an emission line galaxy called NGC 3749.

When astronomers explore the contents and constituent parts of a galaxy somewhere in the Universe, they use various techniques and tools. One of these is to spread out the incoming light from that galaxy into a spectrum and explore its properties. This is done in much the same way as a glass prism spreads white light into its constituent wavelengths to create a rainbow. By hunting for specific signs of emission from various elements within a galaxy’s spectrum of light — so-called emission lines — or, conversely, the signs of absorption from other elements — so-called absorption lines — astronomers can start to deduce what might be happening within.

If a galaxy’s spectrum shows many absorption lines and few emission lines, this suggests that its star-forming material has been depleted and that its stars are mainly old, while the opposite suggests it might be bursting with star formation and energetic stellar newborns. This technique known as spectroscopy, can tell us about a galaxy’s type and composition, the density and temperature of any emitting gas, the star formation rate, or how massive the galaxy’s central black hole might be.

While not all galaxies display strong emission lines, NGC 3749 does! It lies over 135 million light-years away, and is moderately luminous. The galaxy has been used a “control” in studies of especially active and luminous galaxies — those with centres known as active galactic nuclei, which emit copious amounts of intense radiation. In comparison to these active cousins, NGC 3749 is classified as inactive, and has no known signs of nuclear activity.

Image Credit: ESO/Babak Tafreshi (TWAN)

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ESO’s astronomical facilities in Chile are hives of activity — or oases! — in the otherwise barren and arid landscape of the Atacama Desert. This hostile and hard-to-reach location may seem like an odd choice for construction, but the Atacama is one of the best sites in the world for astronomy. It has practically no cloud cover, a distinct lack of light pollution, and is the driest non-polar location in the world, receiving under two centimetres of rainfall every year!

Chile has hosted ESO’s telescopes since the 1960s, in observatories based at La Silla, Paranal, and Chajnantor Plateau. Shown here is the Visible and Infrared Survey Telescope for Astronomy (VISTA), situated at the Paranal Observatory.

Perched atop a mountain adjacent to Cerro Paranal, the home of the flagship Very Large Telescope (VLT), VISTA is the largest telescope in the world designed to survey the sky in near-infrared light (just beyond that visible to humans). The spectacular sights of the cosmos — including the notable streak of our home galaxy, the Milky Way, stretching across the top of the frame here — are more than enough to keep VISTA and its telescopic siblings busy.