Starship Asterisk*

Image Credit: ESO / Petr Horálek

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The telescope in this eye-catching picture is appropriately named VISTA, short for the Visible and Infrared Survey Telescope for Astronomy. The telescope is located at ESO’s Paranal Observatory in Chile, where the altitude and arid climate make for cloudless skies and excellent viewing conditions.

Different phenomena in the Universe produce different kinds of light, only a tiny fraction of which is visible to the human eye. VISTA observes infrared light, the same radiation that we can feel as heat. The three-tonne camera housed inside the telescope is extremely sensitive, allowing VISTA to detect this kind of light from very distant sources in the Universe and to produce both stunning images and groundbreaking scientific results.

Enjoying the same exceptional skies as VISTA is another of ESO’s facilities, the Very Large Telescope (VLT), which can be just about be seen atop a distant peak. Despite the impressive size and ingenuity of these facilities, they cannot help but be dwarfed by the sheer majesty of the Universe above, as demonstrated by the kaleidoscopic Milky Way arching across the panorama.

This image was taken by ESO photo ambassador Petr Horálek.

Image Credit: ESA/Hubble & NASA, A. Evans

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The pair of strange, luminescent creatures at play in this image are actually galaxies — realms of millions upon millions of stars.

This galactic duo is known as UGC 2369. The galaxies are interacting, meaning that their mutual gravitational attraction is pulling them closer and closer together and distorting their shapes in the process. A tenuous bridge of gas, dust, and stars can be seen connecting the two galaxies,, during which they pulled material out into space across the diminishing divide between them.

Interaction with others is a common event in the history of most galaxies. For larger galaxies like the Milky Way, the majority of these interactions involve significantly smaller so-called dwarf galaxies. But every few aeons, a more momentous event can occur. For our home galaxy, the next big event will take place in about four billion years, when it will collide with its bigger neighbour, the Andromeda Galaxy. Over time, the two galaxies will likely merge into one — already nicknamed Milkomeda.

bystander wrote: ↑Mon Aug 05, 2019 2:58 pm Galactic Creatures at Play
ESA Hubble Picture of the Week | 2019 Aug 05

Image Credit: ESA/Hubble & NASA, A. Evans

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The pair of strange, luminescent creatures at play in this image are actually galaxies — realms of millions upon millions of stars.

This galactic duo is known as UGC 2369. The galaxies are interacting, meaning that their mutual gravitational attraction is pulling them closer and closer together and distorting their shapes in the process. A tenuous bridge of gas, dust, and stars can be seen connecting the two galaxies,, during which they pulled material out into space across the diminishing divide between them.

Interaction with others is a common event in the history of most galaxies. For larger galaxies like the Milky Way, the majority of these interactions involve significantly smaller so-called dwarf galaxies. But every few aeons, a more momentous event can occur. For our home galaxy, the next big event will take place in about four billion years, when it will collide with its bigger neighbour, the Andromeda Galaxy. Over time, the two galaxies will likely merge into one — already nicknamed Milkomeda.

Image Credit: ESA/Hubble & NASA, R. Wade

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Although it looks more like an entity seen through a microscope than a telescope, this rounded object, named NGC 2022, is certainly no alga or tiny, blobby jellyfish. Instead, it is a vast orb of gas in space, cast off by an ageing star. The star is visible in the orb's centre, shining through the gases it formerly held onto for most of its stellar life.

When stars like the Sun grow advanced in age, they expand and glow red. These so-called red giants then begin to lose their outer layers of material into space. More than half of such a star's mass can be shed in this manner, forming a shell of surrounding gas. At the same time, the star's core shrinks and grows hotter, emitting ultraviolet light that causes the expelled gases to glow.

This type of object is called, somewhat confusingly, a planetary nebula, though it has nothing to do with planets. The name derives from the rounded, planet-like appearance of these objects in early telescopes.

NGC 2022 is located in the constellation of Orion (The Hunter).

Susanna Kohler wrote:

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How do globular clusters — massive and dense gravitationally bound stellar systems — form? A team of scientists led by Natalia Lahén (University of Helsinki, Finland) explores the possibility that the mergers of gas-rich dwarf galaxies can result in the formation of massive, low-metallicity clusters of stars much like the local globular clusters we observe today. The beautiful series of images above are frames from the authors’ hydrodynamical simulations of the aftermath of a dwarf-galaxy merger. The three sets of panels show surface density of stars (left) and gas (center), and the thermal gas pressure (right), at two times during the simulation (the bottom panels are from 2 million years later than the top). The simulations demonstrate the formation of hundreds of stellar clusters in the filamentary gas structures after merger, including some with properties like local globular clusters.

• Astrophysical Journal Letters 879(2):L18 (2019 Jul 10) DOI: 10.3847/2041-8213/ab2a13
• arXiv.org > astro-ph > arXiv:1905.09840 > 23 May 2019 (v1), 17 Jun 2019 (v2)

starsurfer wrote: ↑Sat Aug 17, 2019 1:10 pm NGC 5559
https://www.spacetelescope.org/images/potw1736a/
Copyright: ESA/Hubble & NASA

Click to view full size image

Spacetelescope wrote:

In 2001, a calcium-rich supernova called 2001co was observed in NGC 5559. Calcium-rich supernovae (Ca-rich SNe) are described as “fast-and-faint”, as they're less luminous than other types of supernovae and also evolve more rapidly, to reveal spectra dominated by strong calcium lines. 2001co occurred within the disc of NGC 5559 near star-forming regions, but Ca-rich SNe are often observed at large distances from the nearest galaxy, raising curious questions about their progenitors.