Starship Asterisk*

vdB126
http://www.skypixels.at/vdb126_info.html
Copyright: Herbert Walter

NGC 6804
http://www.capella-observatory.com/Imag ... GC6804.htm
Copyright: Volker Wendel, Stefan Binnewies, Josef Pöpsel

NGC 6397
http://www.astropilar.com.ar/cumulos/NGC6397_1.html
Copyright: Ezequiel Bellocchio

Reflections of Paranal
ESO Picture of the Week | 2016 July 18

[img3="Credit: ESO/Gerhard Hüdepohl(atacamaphoto.com)"]https://cdn.eso.org/images/screen/potw1629a.jpg[/img3][hr][/hr]

In this image we see a rare sight — water in the Atacama Desert! Reflected on the water’s calm surface we can see the familiar sight of Cerro Paranal, home to ESO’s Paranal Observatory.

This desert is one of the driest and most inhospitable places on Earth. The average rainfall in the Cerro Paranal region is less than 10 millimetres per year, indicating that this photograph was taken just after a period of rare rainfall in the area. Soon after the image was taken, the temporary lagoon evaporated swiftly, leaving the valley floor as dry and desiccated as ever.

However, what is arguably bad for the minimal flora and fauna of the region is excellent for astronomers. The lack of rainclouds and the dry air allow Paranal astronomers to observe all year round. With over 300 clear nights per year, the Atacama Desert is one of the best sites in the world for astronomy, almost always offering an uninterrupted view of the cosmos. ...

A Galaxy Fit to Burst (NGC 3125)
ESA Hubble Picture of the Week | 2016 July 18

[img3="Credit: ESA/Hubble & NASA
Acknowledgement: Judy Schmidt (geckzilla.com)"]https://cdn.spacetelescope.org/archives ... w1629a.jpg[/img3][hr][/hr]

This NASA/ESA Hubble Space Telescope image reveals the vibrant core of the galaxy NGC 3125. Discovered by John Herschel in 1835, NGC 3125 is a great example of a starburst galaxy — a galaxy in which unusually high numbers of new stars are forming, springing to life within intensely hot clouds of gas.

Located approximately 50 million light-years away in the constellation of Antlia (The Air Pump), NGC 3125 is similar to, but unfathomably brighter and more energetic than, one of the Magellanic Clouds. Spanning 15 000 light-years, the galaxy displays massive and violent bursts of star formation, as shown by the hot, young, and blue stars scattered throughout the galaxy’s rose-tinted core. Some of these clumps of stars are notable — one of the most extreme Wolf–Rayet star clusters in the local Universe, NGC 3125-A1, resides within NGC 3125.

Despite their appearance, the fuzzy white blobs dotted around the edge of this galaxy are not stars, but globular clusters. Found within a galaxy’s halo, globular clusters are ancient collections of hundreds of thousands of stars. They orbit around galactic centres like satellites — the Milky Way, for example, hosts over 150 of them.

http://asterisk.apod.com/viewtopic.php?t=36173

RCW 68-9
http://cosmicphotos.com/gallery/image.p ... lbum_id=11
Copyright: Jason Jennings

NGC 1097
http://www.pbase.com/tango33/image/162822621
Copyright: Kfir Simon

NGC 253
http://www.billionsandbillions.com/sculptor.html
Copyright: Warren Keller
Acknowledgement: David Plesko

Dark Doodad
http://www.tvdavisastropics.com/astroim ... 00007b.htm
Copyright: Thomas Davis

vdB134 and We 1-10
http://www.distant-lights.at/vdb134-2015_09_20.htm
Copyright: Thomas Henne

Soyuz and Moon
Copyrights: NASA
Suggested by: Rob Landis

RCW 96, RCW 97 and RCW 98
http://cosmicphotos.com/gallery/image.p ... lbum_id=11
Copyright: Jason Jennings

NGC 6337
http://www.pbase.com/strongmanmike2002/ngc_6337
Copyright: Michael Sidonio

Sh2-1
http://www.atacama-photographic-observatory.com
Copyright: Thierry Demange, Richard Galli and Thomas Petit

A Long-Dead Star (DEM L316A)
ESA Hubble Picture of the Week | 2016 July 25

[c][attachment=0]potw1630a[1].jpg[/attachment][/c][hr][/hr]

This NASA/ESA Hubble Space Telescope image captures the remnants of a long-dead star. These rippling wisps of ionised gas, named DEM L316A, are located some 160 000 light-years away within one of the Milky Way’s closest galactic neighbours — the Large Magellanic Cloud (LMC).

The explosion that formed DEM L316A was an example of an especially energetic and bright variety of supernova, known as a Type Ia. Such supernova events are thought to occur when a white dwarf star steals more material than it can handle from a nearby companion, and becomes unbalanced. The result is a spectacular release of energy in the form of a bright, violent explosion, which ejects the star’s outer layers into the surrounding space at immense speeds. As this expelled gas travels through the interstellar material, it heats it up and ionise it, producing the faint glow that Hubble’s Wide Field Camera 3 has captured here.

The LMC orbits the Milky Way as a satellite galaxy and is the fourth largest in our group of galaxies, the Local Group. DEM L316A is not alone in the LMC; Hubble came across another one in 2010 with SNR 0509 (heic1018), and in 2013 it snapped SNR 0519 (potw1317a).

NGC 4569 (M90) and its satellite galaxy IC 3583
I love this image because of its superb color balance.

M90 is a galaxy that is losing much of its gas due to ram pressure as it is falling through the Virgo Cluster. For that reason, it has stopped forming stars almost entirely. Only in the dust lane near the bulge of M90 is star formation still going on. (Interestingly, M90 is somewhat similar to M64 in that respect, although M64 is an even more extreme case of star formation ceasing everywhere in a disk galaxy except in a dust lane near the bulge. (The M64 picture by Landos France is also beautiful and noteworthy.)

Unlike M64, M90 still has a large youngish, bluish - but not ultraviolet - population. Its colors are interesting: its B-V is 0.720, which is relatively blue for a large galaxy, while its U-B is 0.425, which is quite red for any spiral galaxy. Yes, but compare that to M90's small satellite galaxy, IC 3583: B-V is 0.380, and U-B is -0.290. Blue indeed!

And now look at M90 in Robert Lockwood's picture. Note the cyan color of the young to intermediate population in the smooth, fuzzy spiral arms just outside the bulge. (And note the mostly non-blue and non-cyan color of the outer disk, which appears to be made up mostly of old, possibly somewhat metal-poor stars.)

And now look at IC 3583! The outer disk is slightly bluish and quite likely metal-poor, but the inner, starforming disk is strongly blue. Not cyan. Blue.

I find the colors amazing!

Ann

Propeller Nebula (Simeis 57)
http://www.astrobin.com/255544/
Copyright: Enrico Scheibel

M5
https://www.flickr.com/photos/cfaobam/1 ... 123849630/
Copyright: Carsten Frenzl

Gum 12b
http://www.astrobin.com/241011/
Copyright: Mark Elvov

NGC 6791
http://www.astrobin.com/254806/
Copyright: Tommy Nawratil

NGC 4395
http://www.noao.edu/image_gallery/html/im1269.html
Copyright: T.A. Rector (University of Alaska Anchorage) and H. Schweiker (WIYN and NOAO/AURA/NSF)

Abell 28
http://www.cxielo.ch/gallery/v/nebulae/ ... x.jpg.html
Copyright: Martin Rusterholz