Starship Asterisk*

Image Credit: Petr Horálek/ESO

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Seen here, the majestic Milky Way rises above ESO’s La Silla Observatory in Chile, its bright band punctuated by red regions of star formation and dark, weaving filaments of interstellar dust. Two of the site’s telescopes, the 1-metre Schmidt telescope (left) and the MPG-ESO 2.2-metre telescope (right), are are visible as well.

While all of the stars in the sky belong to the Milky Way galaxy, we commonly refer to this thick streak across the sky as “the Milky Way”. This is because of our position within our home galaxy: the Solar System sits on one of our galaxy’s spiral arms and is located roughly two-thirds of the distance between the Milky Way’s centre and its peripheries. The galaxy itself is shaped a little like a giant pancake with a bright bulge in the centre, with almost all of its constituent stars, gas, dust, planets, and so on lying within a thin disc. The “Milky Way” — the bright strip we see painted across the night sky in this image — is actually our view of this disc, which is why it appears to be so much brighter and more impressive than the surrounding sky, as we look inwards towards the densely-packed galactic centre.

To the centre-right of the frame, just above the MPG-ESO 2.2-metre telescope, is one of our nearest neighbours in space, a dwarf galaxy known as the Large Magellanic Cloud. The pink and green glow visible just above the horizon is known as airglow, and is caused by excited atoms in the Earth’s upper atmosphere.

Credit: NASA/ESA/Hubble, W Li et al Acknowledgements: Judy Schmidt (geckzilla)

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Some of the most dramatic events in the Universe occur when certain stars die — and explode catastrophically in the process.

Such explosions, known as supernovae, mainly occur in a couple of ways: either a massive star depletes its fuel at the end of its life, become dynamically unstable and unable to support its bulk, collapses inwards, and then violently explodes; or a white dwarf in an orbiting stellar couple syphons more mass off its companion than it is able to support, igniting runaway nuclear fusion in its core and beginning the supernova process. Both types result in an intensely bright object in the sky that can rival the light of a whole galaxy.

In the last 20 years the galaxy NGC 5468, visible in this image, has hosted a number of observed supernovae of both the aforementioned types: SN 1999cp, SN 2002cr, SN 2002ed, SN 2005P, and SN 2018dfg. Despite being just over 130 million light-years away, the orientation of the galaxy with respect to us makes it easier to spot these new ‘stars’ as they appear; we see NGC 5468 face on, meaning we can see the galaxy’s loose, open spiral pattern in beautiful detail in images such as this one from the NASA/ESA Hubble Space Telescope.

... full view of the observatory of Johannes Hevelius, a Polish astronomer who lived in the 1600s. This print is found in Hevelius’s book Selenographia and is reproduced courtesy of the Library of the Astronomical Observatory of the Spanish Navy in a recent solar activity research study led by Victor Carrasco (University of Extremadura, Spain and Southwest Research Institute). Hevelius used his observatory to chart daily observations of sunspots (note ... the projection of the Sun’s disk from the telescope coming through the left wall onto a vertical screen at the right). His records from 1642 to 1645 are the only systematic sunspot observations we have from just before the Maunder Minimum, a prolonged period of reduced solar activity between 1645 and 1715. Carrasco and collaborators have now reevaluated Hevelius’s observations, using them to explore the first hints of this quiet time for the Sun. For more information, check out the original article below.

• Astrophysical Journal 886(1):18 (2019 Nov 20) DOI: 10.3847/1538-4357/ab4ade

Credit: ESO/VLT/FORS

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This cloud-strewn new image of RCW 36 (or Gum 20) was captured by ESO’s Focal Reducer and low dispersion Spectrograph (FORS). It shows one of the sites of massive-star formation closest to our Solar System, about 2300 light-years away. Located in the constellation of Vela (The Sails), the RCW 36 emission nebula is only part of an even larger star formation complex, known as the Vela Molecular Ridge.

Some areas in the clouds of RCW 36 are dense enough to block out background light, creating patches and wisps of inky black. Despite the dark appearance of these clouds, they are the only places in the Universe in which star formation occurs; clumps of molecular hydrogen and cosmic dust collapse and come together to form stars encircled by small families of planets, as in our own Solar System.

FORS is mounted on ESO’s Very Large Telescope, one of the world's most advanced astronomical observatories. This image was selected as part of the ESO Cosmic Gems programme, an initiative that produces images of scientifically interesting and visually attractive objects using ESO telescopes for the purposes of education and public outreach. The programme makes use of telescope time that cannot be used for science observations. All data collected may also be suitable for scientific purposes, and are made available to astronomers through ESO’s science archive.

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

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NGC 3175 is located around 50 million light-years away in the constellation of Antlia (The Air Pump). The galaxy can be seen slicing across the frame in this image from the NASA/ESA Hubble Space Telescope, with its mix of bright patches of glowing gas, dark lanes of dust, bright core, and whirling, pinwheeling arms coming together to paint a beautiful celestial scene.

The galaxy is the eponymous member of the NGC 3175 group, which has been called a nearby analogue for the Local Group. The Local Group contains our very own home galaxy, the Milky Way, and around 50 others — a mix of spiral, irregular, and dwarf galaxies. The NGC 3175 group contains a couple of large spiral galaxies — the subject of this image, and NGC 3137 — and numerous lower-mass spiral and satellite galaxies. Galaxy groups are some of the most common galactic gatherings in the cosmos, and they comprise 50 or so galaxies all bound together by gravity.

This image comprises observations from Hubble’s Wide Field Camera 3.

starsurfer wrote: ↑Thu Dec 12, 2019 5:18 pm IC 447 region
http://www.astropilar.com.ar/nebulosas/IC447_1.html
Copyright: Ezequiel Bellocchio
IC447.jpg

P. Donati, G. Cocozza, A. Bragaglia and E. Pancino wrote:

The old, metal-poor, anticentre open cluster Trumpler 5

As part of a long-term programme, we analyse the evolutionary status and properties of the old and populous open cluster Trumpler 5 (Tr 5), located in the Galactic anticentre direction, almost on the Galactic plane...

Our analysis shows that Tr 5 has subsolar metallicity, with [Fe/H] = −0.403 ± 0.006 dex (derived from spectroscopy), age between 2.9 and 4 Gyr (the lower age is found using stellar models without core overshooting), reddening E(B − V) in the range 0.60–0.66 mag complicated by a differential pattern (of the order of ∼±0.1 mag), and distance modulus (m − M)0 = 12.4 ± 0.1 mag.

Image Credit: Yuri Beletsky/ESO

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Difficult as it may be, given the view above, when at Paranal Observatory make sure you keep your eyes on the ground — or you might just take a tumble. This Picture of the Week shows an entrance to one of the laboratories beneath the ESO’s Very Large Telescope (VLT) platform, used to carry out an astronomical technique known as interferometry.

The VLT is composed of four large Unit Telescopes and four smaller Auxiliary Telescopes (ATs) — two of the latter are imaged here. Astronomers can use various combinations of these telescopes to pool their observing power and, using the technique of interferometry, achieve imaging resolutions much greater than is possible by any of them alone. This clever trick is performed beneath the platform in a network of tunnels filled with specialised equipment to direct and process the light gathered by the telescopes.

Paranal Observatory is located in northern Chile atop its mountain namesake, Cerro Paranal. The remote location and high altitude here provide ideal conditions for the kinds of astronomy undertaken at the facility, whether that be peering into star nurseries in the Milky Way or observing the ferociously active cores of distant galaxies.