Starship Asterisk*

bystander wrote:What’s in a name?
ESA Hubble Picture of the Week | 2017 Jun 26

[img3="Credit: ESA/Hubble & NASA"]https://cdn.spacetelescope.org/archives ... w1726a.jpg[/img3][hr][/hr]

Not all galaxies have the luxury of possessing a simple moniker or quirky nickname. The subject of this NASA/ESA Hubble Space Telescope image was one of the unlucky ones, and goes by the rather unpoetic name of 2XMM J143450.5+033843.

Such a name may seem like a random jumble of numbers and letters, but like all galactic epithets it has a distinct meaning. This galaxy, for example, was detected and observed as part of the second X-ray sky survey performed by ESA’s XMM-Newton Observatory. Its celestial coordinates form the rest of the bulky name, following the “J”: a right ascension value of 14h 34m 50.5s (this can be likened to terrestrial longitude), and a declination of +03d 38m 43s (this can be likened to terrestrial latitude). The other fuzzy object in the frame was named in the same way — it is a bright galaxy named 2XMM J143448.3+033749.

2XMM J143450.5+033843 lies nearly 400 million light-years away from Earth. It is a Seyfert galaxy that is dominated by something known as an Active Galactic Nucleus — its core is thought to contain a supermassive black hole that is emitting huge amounts of radiation, pouring energetic X-rays out into the Universe.

[img3="Credit: ESA/Hubble & NASA"]https://cdn.spacetelescope.org/archives ... w1726a.jpg[/img3][hr][/hr]

Not all galaxies have the luxury of possessing a simple moniker or quirky nickname. The subject of this NASA/ESA Hubble Space Telescope image was one of the unlucky ones, and goes by the rather unpoetic name of 2XMM J143450.5+033843.

Such a name may seem like a random jumble of numbers and letters, but like all galactic epithets it has a distinct meaning. This galaxy, for example, was detected and observed as part of the second X-ray sky survey performed by ESA’s XMM-Newton Observatory. Its celestial coordinates form the rest of the bulky name, following the “J”: a right ascension value of 14h 34m 50.5s (this can be likened to terrestrial longitude), and a declination of +03d 38m 43s (this can be likened to terrestrial latitude). The other fuzzy object in the frame was named in the same way — it is a bright galaxy named 2XMM J143448.3+033749.

2XMM J143450.5+033843 lies nearly 400 million light-years away from Earth. It is a Seyfert galaxy that is dominated by something known as an Active Galactic Nucleus — its core is thought to contain a supermassive black hole that is emitting huge amounts of radiation, pouring energetic X-rays out into the Universe.

[img3="Credit: ALMA (ESO/NAOJ/NRAO)/E. O’Gorman/P. Kervella"]https://cdn.eso.org/images/screen/potw1726a.jpg[/img3][hr][/hr]

This orange blob shows the nearby star Betelgeuse, as seen by the Atacama Large Millimeter/submillimeter Array (ALMA). This is the first time that ALMA has ever observed the surface of a star and this first attempt has resulted in the highest-resolution image of Betelgeuse available.

Betelgeuse is one of the largest stars currently known — with a radius around 1400 times larger than the Sun’s in the millimeter continuum. About 600 light-years away in the constellation of Orion (The Hunter), the red supergiant burns brightly, causing it to have only a short life expectancy. The star is just about eight million years old, but is already on the verge of becoming a supernova. When that happens, the resulting explosion will be visible from Earth, even in broad daylight.

The star has been observed in many other wavelengths, particularly in the visible, infrared, and ultraviolet. Using ESO’s Very Large Telescope astronomers discovered a vast plume of gas almost as large as our Solar System. Astronomers have also found a gigantic bubble that boils away on Betelgeuse’s surface. These features help to explain how the star is shedding gas and dust at tremendous rates (eso0927, eso1121). In this picture, ALMA observes the hot gas of the lower chromosphere of Betelgeuse at sub-millimeter wavelengths — where localised increased temperatures explain why it is not symmetric. Scientifically, ALMA can help us to understand the extended atmospheres of these hot, blazing stars.

• arXiv.org > astro-ph > arXiv:1706.06021 > 19 Jun 2017

[img3="ESO/M. Marsset"]https://cdn.eso.org/images/thumb700x/potw1725a.jpg[/img3][hr][/hr]

The region between Mars and Jupiter is teeming with rocky worlds called asteroids. This asteroid belt is estimated to contain millions of small rocky bodies, and between 1.1 and 1.9 million larger ones spanning over one kilometre across. Small fragments of these bodies often fall to Earth as meteorites. Interestingly, 34% of all meteorites found on Earth are of one particular type: H-chondrites. These are thought to have originated from a common parent body — and one potential suspect is the asteroid 6 Hebe, shown here.

Approximately 186 kilometres in diameter and named for the Greek goddess of youth, 6 Hebe was the sixth asteroid ever to be discovered. These images were taken during a study of the mini-world using the SPHERE instrument on ESO’s Very Large Telescope, which aimed to test the idea that 6 Hebe is the source of H-chondrites.

Astronomers modelled the spin and 3D shape of 6 Hebe as reconstructed from the observations, and used their 3D model to determine the volume of the largest depression on 6 Hebe — likely an impact crater from a collision that could have created numerous daughter meteorites. However, the volume of the depression is five times smaller than the total volume of nearby asteroid families with H-chondrite composition, which suggests that 6 Hebe is not the most likely source of H-chondrites after all.

• Astronomy & Astrophysics (Accepted: 19 May 2017) DOI: 10.1051/0004-6361/201731021
  arXiv.org > astro-ph > arXiv:1705.10515 > 30 May 2017

[img3="Credit: ESA/Hubble & NASA"]https://cdn.spacetelescope.org/archives ... w1725a.jpg[/img3][hr][/hr]

The object in the middle of this image, sitting alone within a star-studded cosmos, is a galaxy known as ESO 486-21. ESO 486-21 is a spiral galaxy — albeit with a somewhat irregular and ill-defined structure — located some 30 million light-years from Earth.

The NASA/ESA Hubble Space Telescope observed this object while performing a survey — the Legacy ExtraGalactic UV Survey (LEGUS) — of 50 nearby star-forming galaxies. The LEGUS sample was selected to cover a diverse range of galactic morphologies, star formation rates, galaxy masses, and more. Astronomers use such data to understand how stars form and evolve within clusters, and how these processes affect both their home galaxy and the wider Universe. ESO 486-21 is an ideal candidate for inclusion in such a survey as it is known to be in the process of forming new stars, which are created when large clouds of gas and dust (seen here in pink) within the galaxy crumple inwards upon themselves.

LEGUS made use of Hubble’s Wide Field Camera 3 (WFC3) and Advanced Camera for Surveys (ACS). The WFC3 obtained detailed observations of the target objects while the ACS obtained what are known as parallel fields — instead of leaving ACS idle, it was instead trained on a small patch of sky just offset from the target field itself, allowing it to gather additional valuable information while the primary target was being observed by WFC3. Parallel fields played an important role in Hubble’s Frontier Fields programme, which used the magnifying power of large galaxy clusters (via a phenomenon known as gravitational lensing) to explore objects in the distant Universe.

bystander wrote:

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Waltzing Dwarfs
ESA Hubble Picture of the Week

The observed system, Luhman 16AB, is only about six light-years away and is the third closest stellar system to Earth — after the triple star system Alpha Centauri and Barnard’s Star. Despite its proximity, Luhman 16AB was only discovered in 2013 by the astronomer Kevin Luhman. The two brown dwarfs that make up the system, Luhman 16A and Luhman 16B, orbit each other at a distance of only three times the distance between the Earth and the Sun, and so these observations are a showcase for Hubble’s precision and high resolution.

https://en.wikipedia.org/wiki/Luhman_16 wrote:

Click to play embedded YouTube video.

<<A study by Gillon et al. (2013) found that Luhman 16B exhibited uneven surface illumination during its rotation. On 5 May 2013, Crossfield et al. (2014) used the European Southern Observatory's Very Large Telescope (VLT) to directly observe the Luhman 16 system for five hours, the equivalent of a full rotation of Luhman 16B. Their research confirmed Gillon et al.'s observation, finding a large, dark region at the middle latitudes, a bright area near its upper pole, and mottled illumination elsewhere. They suggest this variant illumination indicates "patchy global clouds", where darker areas represent thick clouds and brighter areas are holes in the cloud layer permitting light from the interior. Gillon et al. determined that Luhman 16B's illumination patterns change rapidly, on a day-to-day basis. Although Luhman 16A has also been observed in the same fashion as 16B, no similar variance in illumination was found.>>