Found Images: 2018 October

[starsurfer]

Sh2-216
http://www.skymonsters.net/immagine.php?img=Sh2-216.jpg
Copyright: Nicola Montecchiari

[Ann]

IC 4870
Credit: ESA/Hubble & NASA

Click to view full size image

European Space Agency wrote:

A ripple of bright blue gas threads through this galaxy like a misshapen lake system. The foreground of this image is littered with nearby stars with their gleaming diffraction spikes. A keen eye can also spot a few other galaxies that, while masquerading as stars at first glance, reveal their true nature on closer inspection.

The central galaxy streaked with color, IC 4870, was discovered by DeLisle Stewart in 1900 and is located approximately 28 million light-years away. It contains an active galactic nucleus: an extremely luminous central region so alight with radiation that it can outshine the rest of the galaxy put together...

I have not been able to find out what filters were used for this image, but clearly the blue ripples seen in the central part of the galaxy are really bright red clouds of ionized hydrogen. Nevertheless, the galaxy is amazingly blue. According to PGC, the Principal Galaxy Catalog, the U-B and B-V indexes of IC 4870 are -0.330 and 0.030, respectively. I have come across galaxies with more negative U-B indexes than -0.330, such as NGC 3310, but I have never before seen a galaxy with a B-V index as blue as 0.030.

Imagine an entire galaxy whose combined light output is bluer than the light of Deneb. Of course, IC 4870 is a small faint galaxy with a brilliant blue central starburst. That is what it takes to get a galaxy as blue as this one.

Ann

[Ann]

NGC 4858

Credit: ESA/Hubble & NASA

Click to view full size image

European Space Agency wrote:

In the northern constellation of Coma Berenices (Berenice's Hair) lies the impressive Coma Cluster —  a structure of over a thousand galaxies bound together by gravity. Many of these galaxies are elliptical types, as is the brighter of the two galaxies dominating this image: NGC 4860 (center). However, the outskirts of the cluster also host younger spiral galaxies that proudly display their swirling arms. Again, this image shows a wonderful example of such a galaxy in the shape of the beautiful NGC 4858, which can be seen to the left of its bright neighbor and which stands out on account of its unusual, tangled, fiery appearance.

NGC 4858 is special. Rather than being a simple spiral, it is something called a “galaxy aggregate,” which is as the name suggests a central galaxy surrounded by a handful of luminous knots of material that seem to stem from it, extending and tearing away and adding to or altering its overall structure. It is also experiencing an extremely high rate of star formation...

Ann

[bystander]

IC 4870

Threads of Blue
ESA Hubble Picture of the Week | 2018 Jun 04

NGC 4858

Knots and Bursts
ESA Hubble Picture of the Week | 2018 Sep 17

[starsurfer]

IC 2872
http://www.chart32.de/index.php/component/k2/item/139
Copyright: CHART32
Processing: Johannes Schedler

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Abell 5
http://www.pbase.com/skybox/image/167010247
Copyright: Kevin Quin

[starsurfer]

vdB96 and NGC 2362
http://www.astro-austral.cl/imagenes/ne ... 5/info.htm
Copyright: José Joaquin Perez

[Ann]

vdB96 and NGC 2362
http://www.astro-austral.cl/imagenes/ne ... 5/info.htm
Copyright: José Joaquin Perez
vdb96.jpg

Click to view full size image

If NGC 2362 were an engagement ring, it might look like this!

That's a lovely image! NGC 2362 is obviously one of my favorite clusters. Not only because all the brightest stars are blue - although that certainly helps!!! - but because the luminary of the cluster, Tau Canis Majoris, is such a remarkable star. It is much brighter than all the other stars in NGC 2362, and I believe that it might be one of the brightest stars within the nearest, oh, 5,000 light-years or so.

Not only is NGC 2362 beautiful because of all the blue light it produces, but I also love the way the other blue stars surround the central sparkling "gemstone" like a breathtaking piece of cosmic jewelery.

Ann

[bystander]

Cloudlets Swarm around our Local Supermassive Black Hole
ESO Picture of the Week | ALMA | 2018 Oct 22

Credit: ALMA (ESO/NAOJ/NRAO) / J.R. Goicoechea (IFF, CSIC, Spain)

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This image from the Atacama Large Millimeter/submillimeter Array (ALMA) shows the area surrounding Sagittarius A*, the supermassive black hole that lurks at the centre of the Milky Way — highlighted here with a small circle. New research has revealed exciting evidence of interstellar gas and dust orbiting the black hole at high speeds.

The molecular-hydrogen-rich gas clouds which have been identified are known as molecular cloudlets, and they have never before been unambiguously detected. This image actually shows the distribution of molecules including carbon monoxide, the cloudlets’ second most abundant molecular component. The cloudlets lie 26 000 light-years away from us, orbiting fast and relatively close to the black hole, at a distance of about one light year. ALMA’s high resolution allowed scientists to detect the cloudlets, which are the products of pre-existing massive clouds rotating around the centre of our galaxy. These clouds were tidally disrupted into dense fragments and a lower density, short-lived component. The latter was identified thanks to the signs left by the passage of the synchrotron radiation emitted by Sagittarius A* through diffuse gas between the cloudlets.

Although clouds of molecular gas have the potential to form new stars, these cloudlets are unlikely to create stellar newborns. They have a comparatively small mass of around 60 times that of the Sun, and exist close to the huge, turbulent, punishing gravitational forces exerted by Sagittarius A*.

While the stars orbiting Sagittarius A* have been systematically observed, these dense molecular cloudlets have not been detected so close to the centre of our galaxy before.

High-Speed Molecular Cloudlets around the Galactic Center's Supermassive Black Hole ~ Javier R. Goicoechea et al

• Astronomy & Astrophysics 618:A35 (Oct 2018) DOI: 10.1051/0004-6361/201833558
  arXiv.org > astro-ph > arXiv:1806.01748 > 05 Jun 2018 (v1), 11 Aug 2018 (v3)

[bystander]

A Galaxy with a Bright Heart
ESA Hubble Picture of the Week | 2018 Oct 22

Credit: NASA/ESA/Hubble; Acknowledgement: Judy Schmidt

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This Picture of the Week shows the unbarred spiral galaxy NGC 5033, located about 40 million light-years away in the constellation of Canes Venatici (The Hunting Dogs). The galaxy is similar in size to our own galaxy, the Milky Way, at just over 100 000 light-years across. Like in the Milky Way NGC 5033’s spiral arms are dotted with blue regions, indicating ongoing star formation. The blue patches house hot, young stars in the process of forming, while the older, cooler stars populating the galaxy’s centre cause it to appear redder in colour.

In contrast to the Milky Way NGC 5033 is missing a central bar. Instead it has a bright and energetic core called an active galactic nucleus, which is powered by a supermassive black hole. This active nucleus gives it the classification of a Seyfert galaxy. Due to the ongoing activity the core of NGC 5033 shines bright across the entire electromagnetic spectrum. This released energy shows that the central black hole is currently devouring stars, dust and gas getting to close to it. As this matters falls onto the supermassive black hole, it radiates in many different wavelengths.

While its relative proximity to Earth makes it an ideal target for professional astronomer to study its active nucleus in more detail, its big apparent size on the night sky and its brightness also makes it a beautiful target for amateur astronomers.

[Ann]

A Galaxy with a Bright Heart
ESA Hubble Picture of the Week | 2018 Oct 22

Credit: NASA/ESA/Hubble; Acknowledgement: Judy Schmidt

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This Picture of the Week shows the unbarred spiral galaxy NGC 5033, located about 40 million light-years away in the constellation of Canes Venatici (The Hunting Dogs). The galaxy is similar in size to our own galaxy, the Milky Way, at just over 100 000 light-years across. Like in the Milky Way NGC 5033’s spiral arms are dotted with blue regions, indicating ongoing star formation. The blue patches house hot, young stars in the process of forming, while the older, cooler stars populating the galaxy’s centre cause it to appear redder in colour.

In contrast to the Milky Way NGC 5033 is missing a central bar. Instead it has a bright and energetic core called an active galactic nucleus, which is powered by a supermassive black hole. This active nucleus gives it the classification of a Seyfert galaxy. Due to the ongoing activity the core of NGC 5033 shines bright across the entire electromagnetic spectrum. This released energy shows that the central black hole is currently devouring stars, dust and gas getting to close to it. As this matters falls onto the supermassive black hole, it radiates in many different wavelengths.

While its relative proximity to Earth makes it an ideal target for professional astronomer to study its active nucleus in more detail, its big apparent size on the night sky and its brightness also makes it a beautiful target for amateur astronomers.

Click to view full size image

NGC 5033. Photo: Adam Block.

Very interesting!

I checked NGC 5033 with my software Guide, and found that NGC 5033 has a B-V index of 0.55. That is really blue for a large galaxy. The Milky Way, by contrast, likely has a B-V index of, perhaps, 0.85.

Yet NGC 5033 looks rather red in the Hubble image. That is because the Hubble image zooms in on the very reddest part of NGC 5033. Adam Block's excellent picture shows us exactly where that extremely dusty, highly reddened part of NGC 5033 is located.

I need to point out that Adam Block often makes the bluish parts of galaxies look really quite blue. I love that, of course. Others may disagree. Nevertheless, a comparison between the Hubble image and Adam Block's picture gives us a good idea of the overall characteristics of the galaxy versus the Hubble closeup of a part of it.

Click to view full size image

M31. Photo: Adam Evans.

For comparison, I have included a picture of M31, our great neighboring galaxy in Andromeda. It is likely that the Milky Way is about as dominated by yellow stars as M31 is, whereas, by contrast, NGC 5033 sports some wild spiral arms with a very large number of bright blue stars.

Ann

[canopia]

Voyage of the Moons
Processed by: Kevin Gill (NASA-JPL)
https://www.flickr.com/photos/kevinmgill/44583965185/

[starsurfer]

M23
http://www.astroimager.net/Page-AP160-CCD-417.html
Copyright: Jim Janusz

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Pelican Nebula (IC 5070)
http://www.capella-observatory.com/Imag ... anPrim.htm
Copyright: Frank Sackenheim, Josef Pöpsel and Stefan Binnewies

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Iris Nebula (NGC 7023)
https://www.flickr.com/photos/130138181 ... 977737368/
Copyright: Yves Van den Broek

The nebula on the right is vdB141.

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IC 448
https://www.flickr.com/photos/whiskey_c ... 603852842/
Copyright: Kent de Groff

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NGC 660
https://www.astrobin.com/317199/0/
Copyright: Dan Wilson

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Zwicky 7876
http://www.capella-observatory.com/Imag ... ky7876.htm
Copyright: Frank Sackenheim, Stefan Binnewies and Josef Pöpsel

Click to view full size image

[starsurfer]

NGC 1221
http://www.chart32.de/index.php/component/k2/item/274
Copyright: CHART32
Processing: Bernd Flach-Wilken

Click to view full size image

[starsurfer]

BHR 71
https://astrodonimaging.com/gallery/bhr-71-dark-cloud/
Copyright: Don Goldman

[starsurfer]

Eta Carinae Nebula (NGC 3372)
http://www.astrostudio.at/1_Deep%20Sky% ... a75b68906f
Copyright: Gerald Rhemann

Click to view full size image

[bystander]

Extremely Large Astronomy
ESO Picture of the Week | 2018 Oct 29

Image Credit: G. Hüdepohl / ESO

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The era of extremely large telescopes is beginning — and it will revolutionise our understanding of the Universe. ESO’s Extremely Large Telescope (ELT) is currently under construction in the remote Chilean Atacama Desert; this groundbreaking telescope alone will collect more light than over 200 NASA/ESA Hubble Space Telescopes.

As the name suggests, such telescopes are truly colossal. The largest primary mirrors — by which a telescope collects light — currently in operation at all of ESO’s sites are the 8.2-metre-diameter mirrors in the four Unit Telescopes comprising the Very Large Telescope (VLT). The ELT will dwarf the already impressive VLT with its vast mirror at 39 metres in diameter! However, constructing a single, science-quality mirror of such a size is simply not possible — the ELT’s primary mirror will, in fact, be a complex honeycomb arrangement of 798 tessellated hexagonal 1.4-metre mirrors.

Finding a suitable place for such a structure was also no easy task. As well as requiring the dry and light-pollution-free conditions at a high altitude necessary for successful astronomy, the ELT needed a huge space on which to spread its foundations. As such a location was not available, it was created! The complex journey of the ELT’s construction began by flattening the top of the Cerro Armazones mountain in Chile, taking 18 metres off its full height. That site is now covered by a web of foundations — as seen in this image.

[bystander]

Helping Hubble
ESA Hubble Picture of the Week | 2018 Oct 29

Credit: ESA/Hubble & NASA; Acknowledgement: Judy Schmidt

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The NASA/ESA Hubble Space Telescope doesn’t usually get much assistance from its celestial subjects — but to take this image, the telescope opted for teamwork and made good use of a fascinating cosmic phenomenon known as gravitational lensing.

This effect works when the gravitational influence of a massive object, such as the galaxy cluster in the centre of this image, is so colossal that it warps the surrounding space, causing nearby light to travel along distorted paths. The massive object is effectively turned into a giant magnifying glass, bending and amplifying the light travelling from more distant galaxies lying behind it.

In this particular case, astronomers used the foreground galaxy cluster (named SDSS J0915+3826) to study star formation in galaxies lying so far away that their light has taken up to 11.5 billion years to reach our eyes. These galaxies formed at a very early stage in the lifetime of the Universe, giving astronomers a rare glimpse into the beginning of the cosmos. Despite their distance, the lensing effects of SDSS J0915+3826 allowed astronomers to work out the sizes, luminosities, star formation rates, and stellar populations of individual star-forming clumps within these galaxies — quite an achievement!

[Ann]

Helping Hubble
ESA Hubble Picture of the Week | 2018 Oct 29

Credit: ESA/Hubble & NASA; Acknowledgement: Judy Schmidt

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Beautiful and fascinating picture. Thanks, ESA/Hubble & NASA and Geck.

Ann

[starsurfer]

Wouldn't it be nice if the new monthly threads were started on the first day of each month? Could there be an automatic script that does this?