Starship Asterisk*

starsurfer wrote: ↑Sat Feb 01, 2020 5:24 pm MBM 28 and NGC 2633
http://www.astrosurf.com/ilizaso/orriak ... Q_U16m.htm
Copyright: Iñaki Lizaso
NGC2633IFN-MBM28.jpg
NGC 2633 is the barred spiral galaxy below the elliptical galaxy NGC 2634 near the bottom right corner of the image.

Image Credit: ESO/Zdenek Bardon

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This remarkable photo shows the ESO La Silla observatory in the foreground with the planets Venus and Jupiter low in the sky and the Milky Way drifting behind them. Yet it took Zdenek Bardon, the photographer, three nights to capture this stunning image; astrophotographers are subject to the whims of the weather and this photo was no exception. He had to wait three days for a crystal clear night with no clouds and low humidity to capture Venus, Jupiter and the Milky Way in all their glory.

La Silla is an exceptional location for astronomy because it has relatively low light pollution which allows the stars to appear crystal clear — although lights from human dwellings are visible on the horizon in this image. The site also offers exceptionally low humidity thanks to its elevation of 2400 metres above sea level. High humidity is a problem for both professional astronomers and astrophotographers. Mirrors and lenses risk being filmed over by condensation and some parts of the electromagnetic spectrum are absorbed by the denser water vapour present in high-humidity atmosphere.

On most nights, this observation site does not experience atmospheric disturbances such as clouds and rain, but very unusually Bardon needed to wait two extra nights for this shot. And it was worth the wait! Not only does it show how beautiful the views are in the Atacama desert, it also demonstrates the high-quality viewing conditions that both the 3.6-metre telescope and the New Technology Telescope, run by ESO, enjoy.

The Milky Way appears as the ribbon of stars across the horizon. Venus is the largest spot of light on the left side of the screen and Jupiter is the smaller dot of light below and slightly to the right.

Image Credit: ESA/Hubble & NASA, L. Ho

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This eye-catching galaxy is known as NGC 5364.

Unmistakably a spiral, NGC 5364 is also something known as a grand design spiral galaxy — a descriptive name deserved by only one-tenth of spirals. While all spirals have a structure that is broadly similar, there is quite a bit of variation amongst individual galaxies; some have patchy, oddly-shaped arms, some have bars of stars cutting through their core, some are colossal and radiant, and others are dim and diminutive. Grand designs like NGC 5364 are in many ways the archetype of a spiral galaxy. They are characterised by their prominent, well-defined arms, which circle outwards from a clear core.

Despite being classified in this way, NGC 5364 is far from perfect. Its arms are asymmetrical compared to other grand design spirals — this is thought to be due to interactions with a nearby neighbour. This neighbour and NGC 5364 are tugging on one another, warping and moving their stars and gas around and causing this misshapen appearance.

This image was captured by the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys.

Image Credit: ESO/Petr Horálek

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Stars are surrounded by something known as a corona — a diffuse aura of plasma that appears to surround them in the sky. For the Sun, we can best see this corona during a solar eclipse, when the Moon passes in front of the Sun and covers our star’s face. The solar corona then appears as a bright ring surrounding the eclipsed Sun. An image of the Sun’s corona as seen during a 1999 eclipse can be seen here.

However, there is also the optical phenomenon of a corona, caused by the diffraction of light from a bright object — such as the Sun, other stars, the Moon, and bright planets — by water drops or ice crystals in the Earth’s atmosphere. This is occurring in this unusual image, where a rare corona of the planet Jupiter can be seen above the Atacama Desert in Chile. The beautiful red and green colours in the sky are due to atmospheric airglow, another light-related optical phenomenon. Airglow is explained in detail in this ESOcast.

This image was taken by Petr Horálek some 100 kilometres south of the Chajnantor Plateau, which is home to the Atacama Large Millimetre/submillimetre Array (ALMA).

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

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The spiral galaxy NGC 2008 sits centre stage, its ghostly spiral arms spreading out towards us, in this image captured by the NASA/ESA Hubble Space Telescope.

This galaxy is located about 425 million light-years from Earth in the constellation of Pictor (The Painter’s Easel). Discovered in 1834 by astronomer John Herschel, NGC 2008 is categorised as a type Sc galaxy in the Hubble sequence, a system used to describe and classify the various morphologies of galaxies. The “S” indicates that NGC 2008 is a spiral, while the “c” means it has a relatively small central bulge and more open spiral arms. Spiral galaxies with larger central bulges tend to have more tightly wrapped arms, and are classified as Sa galaxies, while those in between are classified as type Sb.

Spiral galaxies are ubiquitous across the cosmos, comprising over 70% of all observed galaxies — including our own, the Milky Way. However, their ubiquity does not detract from their beauty. These grand, spiralling collections of billions of stars are among the most wondrous sights that have been captured by telescopes such as Hubble, and are firmly embedded in astronomical iconography.

Susanna Kohler wrote:

You’re looking at a 55’ x 55’ Deep Sky Survey image of the Rosette Nebula (click for the full view), a large, spherical, star-forming region located about 5,200 light-years away. In a recent study led by Koraljka Mužić (University of Lisbon, Portugal), a team of scientists has used the Gemini South telescope in Chile to obtain near-infrared images from deep in the heart of the nebula. Zooming in on a region of less than 25 square light-years (the central cyan-outlined region in the photos above and to the right), Mužić and collaborators have imaged the center of NGC 2244, a young, high-density stellar cluster forming massive stars. In their study, the authors seek to understand how low-mass stars and brown dwarfs form and evolve among their high-mass siblings in these extreme environments.

• Astrophysical Journal 881(1):79 (2019 Aug 10) DOI: 10.3847/1538-4357/ab2da4
• arXiv.org > astro-ph > arXiv:1907.00617 > 01 Jul 2019 (v1), 30 Jul 2019 (v2)