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Merging Galaxies

In this image, taken by the Hubble Space Telescope, you can see NGC 2623 (Arp 243), two galaxies in the process of merging in the constellation of Cancer (The Crab, https://goo.gl/gu8e5H), about 250 million light-years away from Earth.

NGC 2623 was formed by the collision of two galaxies, now merging (https://goo.gl/C1SCNa) into one bigger galaxy. You can see clouds of gas lighting up with heavy star formation (https://goo.gl/Mn2Zxf), caused by the compression of the collision.

Also visible are two tidal tails (https://goo.gl/4nQyFx), about 50,000 light-years long each and caused by the enormous tidal forces of the collision.

In the background you can see many more, far distant, galaxies.

More information here:
https://www.spacetelescope.org/images/potw1742a/

More information and images here:
https://apod.nasa.gov/apod/ap121019.html
https://apod.nasa.gov/apod/ap091109.html
https://www.spacetelescope.org/images/heic0912a/

Image credit: NGC 2623 ESA/Hubble & NASA https://goo.gl/BXqb6h CC BY 4.0 https://goo.gl/hNRHCd

Thank you for your interest in this Astronomy/Astrophysics collection. Maybe add me on Google+ (+Pierre Markuse) and Twitter (https://twitter.com/Pierre_Markuse) or have a look at the Space/Space Technology collection here: https://goo.gl/5KP0wx

#science #astronomy #astrophysics #ngc2623 #arp243 #merger #galaxymerger #space #hubble #hst
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Sharpless 132 Nebula

In this image, taken by +Nicolas Kizilian using a William Optics Zenithstar 66 Telescope and a Moravian G2-8300 camera, you can see Sharpless 132 (Sh2-132, LBN 473) , an HII region type emission nebula in the constellation of Cepheus (https://goo.gl/h8tIIA), about 10,400 light-years away from Earth.

The nebula is ionized by a bunch of hot and massive stars with strong ultraviolet radiation, most notably the two Wolf-Rayet stars HD 211564 (https://goo.gl/Rxk8p3) and HD 211853 (https://goo.gl/JadPa2).

The bubble-like structure you can see is most likely caused by stellar winds (https://goo.gl/Z9Sotn) of massive stars.

Visible at the very right side center of the image is the small open cluster (https://goo.gl/fM4XdP) Berkeley 94. In the bottom left you can see the open cluster NGC 7235.

In the top right you can see a small red ring-like feature called Abell 79, most likely a planetary nebula.

What is an emission nebula?

An emission nebula is a cloud of ionized gas (often by ultraviolet radiation from nearby stars) emitting light of various colors, in case of HII mostly reddish-pink (if viewed in natural colors). More information here:
https://en.wikipedia.org/wiki/Emission_nebula
https://en.wikipedia.org/wiki/H_II_region

What is a Wolf-Rayet star?

Wolf-Rayet stars are massive stars that have extremely high surface temperatures of 30,000 K to around 200,000 K. They are also very luminous, some of them several million times more luminous than our Sun, although much of their radiation output is in the ultraviolet part (https://goo.gl/6sMI2) of the spectrum and not the visible part. They blast strong winds of particles out into space while burning up their fuel, lasting only a few hundred thousand years, a short life for a star. More information here:
https://en.wikipedia.org/wiki/Wolf%E2%80%93Rayet_star

What is a planetary nebula?

A planetary nebula is an emission nebula (https://goo.gl/QtI28t), it is basically a shell of glowing ionized gas ejected from old red giant stars and driven by the ultraviolet radiation of the resulting young and hot white dwarf (https://goo.gl/HGYVfx). They are short-lived objects, lasting a few tens o
f thousands of years until the white dwarf has cooled down so much that its not putting out enough ultraviolet radiation anymore and the gas no longer gets ionized. More here:
https://en.wikipedia.org/wiki/Planetary_nebula
https://en.wikipedia.org/wiki/Red_giant

Read more about the different types of nebulae here in this article I wrote for PhotographingSpace:
https://photographingspace.com/what-are-nebulae/

And in case you want to know more about colors in astrophotography, take a look here:
https://photographingspace.com/ap-color/

Image credit: Sharpless 132 +Nicolas Kizilian https://goo.gl/XByRWx Used with permission

If you like this image, you can find Nicolas here on G+ (+Nicolas Kizilian), on Twitter (https://twitter.com/NKizilian) and on Facebook (https://www.facebook.com/NicolasKizilian) and see more of his work here on his website: http://www.astropixels.fr

Thank you for your interest in this Astronomy/Astrophysics collection. Maybe add me on Google+ (+Pierre Markuse) and Twitter (https://twitter.com/Pierre_Markuse) or have a look at the Space/Space Technology collection here: https://goo.gl/5KP0wx

#science #astronomy #astrophotograpy #emissionnebula #space #photography #hiiregion #sharpless132 #sh2132 #wolfrayetstar #abell79 #ngc7235 #opencluster
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Honeycomb Nebula and Tarantula Nebula

In this image, taken by the Hubble Space Telescope, you can see the Honeycomb Nebula (https://goo.gl/9JqEJH), a supernova remnant, and the Tarantula Nebula (https://goo.gl/GJhVX6), an HII type emission nebula, both located in the constellation of Dorado (The Dolphinfish, https://goo.gl/vz9CzY), about 160,000 light-years away from Earth in the Large Magellanic Cloud.

The Tarantula Nebula is one of the largest regions of ongoing star formation (https://goo.gl/Mn2Zxf) we know of.

The Honeycomb Nebula is the remnant of supernova SN1987A (https://goo.gl/cfnTeB), the closest observed supernova to Earth for over 400 years.

More information here:
https://www.spacetelescope.org/images/potw1740a/

What is an emission nebula?

An emission nebula is a cloud of ionized gas (often by ultraviolet radiation from nearby stars) emitting light of various colors, in case of HII mostly reddish-pink (when viewed in natural colors). More information here:
https://en.wikipedia.org/wiki/Emission_nebula
https://en.wikipedia.org/wiki/H_II_region

The Large Magellanic Cloud

The Large Magellanic Cloud (LMC) is a satellite galaxy of our Milky Way, its distance to Earth is about 160,000 light-years. It has a diameter of about 14,000 light-years and is it roughly 1/100 times as massive as the Milky Way. It is quite a large object in the sky, with an apparent size more than 20 times the width of the full moon. More information here:
https://en.wikipedia.org/wiki/Large_Magellanic_Cloud

Take a look here for an image of the Large Magellanic Cloud:
https://plus.google.com/+PierreMarkuse/posts/K9rvmPMLd5f

Image credit: Honeycomb Nebula ESA/Hubble & NASA Acknowledgements: Judy Schmidt (Geckzilla) https://goo.gl/JMF1dA CC BY 4.0 https://goo.gl/hNRHCd

Thank you for your interest in this Astronomy/Astrophysics collection. Maybe add me on Google+ (+Pierre Markuse) and Twitter (https://twitter.com/Pierre_Markuse) or have a look at the Space/Space Technology collection here: https://goo.gl/5KP0wx

#science #astronomy #astrophysics #supernova #tarantulanebula #lmc #largemagellaniccloud #hubble #space #hst #emissionnebula #supernovaremnant
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Barred Spiral Galaxy NGC 1964

In this image, taken by the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory, Chile, you can see NGC 1964. It is a barred spiral galaxy (https://goo.gl/d3D1xC), located in the constellation of Lepus (The Hare, https://goo.gl/zGO0Vb), about 70 million light-years away from Earth.

The galaxy features four spiral arms, two inner arms and two outer arms and has a diameter of about 50,000 light-years.The outer arms are home to a few HII regions (https://goo.gl/glgWjw).

NGC 1964 was discovered November 20th, 1784, by the English astronomer William Herschel (https://goo.gl/E9YsKH).

More information here:
http://www.eso.org/public/images/potw1739a/

More on the morphological classification of galaxies:
https://en.wikipedia.org/wiki/Galaxy_morphological_classification

Image credit: NGC 1964 ESO/Jean-Christophe Lambry https://goo.gl/qRUh9N CC BY 4.0 https://goo.gl/hNRHCd

Thank you for your interest in this Astronomy/Astrophysics collection. Maybe add me on Google+ (+Pierre Markuse) and Twitter (https://twitter.com/Pierre_Markuse) or have a look at the Space/Space Technology collection here: https://goo.gl/5KP0wx

#science #astronomy #ngc1964 #galaxy #spiralgalaxy #space #wfi #eso #barredspiralgalaxy
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Quickie: Hurricane Jose

Hurricane Jose on September 19th, 2017, as seen by the MODIS instrument aboard the Aqua satellite (https://goo.gl/t3Td1Z).

Full-size:
https://flic.kr/p/XDhkGe

More images of Earth from Space:
https://www.flickr.com/photos/pierre_markuse/

Image credit: Hurricane Jose Aqua MODIS data through NASA Worldview, Processed by Pierre Markuse

Thank you for your interest in this Space/Space technology collection. Maybe add me on Google+ (+Pierre Markuse) and Twitter (https://twitter.com/Pierre_Markuse) or have a look at the Astronomy/Astrophysics collection here: https://goo.gl/x0zPAJ

#science #earth #aqua #modis #hurricane #hurricanejose #hurricanejose2017 #satelliteimages #spacetechnology #photography
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Spiral Galaxy NGC 6753

In this image, taken by the Hubble Space Telescope, you can see NGC 6753. It is a spiral galaxy (https://goo.gl/D3uAeP), located in the constellation of Pavo (The Peacock, https://goo.gl/6GQKNp), about 150 million light-years away from Earth.

NGC 6753 is close enough - in astronomical terms - to allow for detailed studies of its galactic corona (https://goo.gl/aWpeVo). A giant sphere of invisible hot gas surrounding the galaxy.

The blue areas in the spiral arms are zones of ongoing star formation (https://goo.gl/Mn2Zxf).

NGC 6753 was discovered on July 5th, 1836, by the English astronomer John Herschel (https://goo.gl/WCo123).

More information here:
https://www.spacetelescope.org/images/potw1738a/

More on the morphological classification of galaxies:
https://en.wikipedia.org/wiki/Galaxy_morphological_classification

Image credit: NGC 6753 ESA/Hubble & NASA Acknowledgement: Judy Schmidt https://goo.gl/mVUWFZ CC BY 4.0 https://goo.gl/hNRHCd

Thank you for your interest in this Astronomy/Astrophysics collection. Maybe add me on Google+ (+Pierre Markuse) and Twitter (https://twitter.com/Pierre_Markuse) or have a look at the Space/Space Technology collection here: https://goo.gl/5KP0wx

#science #astronomy #astrophysics #ngc6753 #galaxy #spiralgalaxy #hubble #hst #space #galacticcorona
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NGC 5398 - Barred spiral galaxy

In this image, taken by the Hubble Space Telescope, you can see NGC 5398. It is a barred spiral galaxy (https://goo.gl/d3D1xC), located in the constellation of Centaurus (https://goo.gl/DVAgmW), about 55 million light-years away from Earth.

The galaxy shows massive amounts of recent star formation (https://goo.gl/Mn2Zxf) in large HII regions (https://goo.gl/glgWjw), it is also home to seven massive star clusters (https://goo.gl/N8o03l).

NGC 5398 was discovered on June 3rd, 1836, by the English astronomer John Herschel (https://goo.gl/WCo123).

More information here:
https://www.spacetelescope.org/images/potw1737a/

Image credit: NGC 5398 ESA/Hubble & NASA https://goo.gl/1YGtnk CC BY 4.0 https://goo.gl/hNRHCd

Thank you for your interest in this Astronomy/Astrophysics collection. Maybe add me on Google+ (+Pierre Markuse) and Twitter (https://twitter.com/Pierre_Markuse) or have a look at the Space/Space Technology collection here: https://goo.gl/5KP0wx

#science #astronomy #ngc5398 #galaxy #barredspiralgalaxy #starburst #hubble #hst #space
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NGC 5559 - Spiral Galaxy

In this image, taken by the Hubble Space Telescope, you can see NGC 5559. It is a spiral galaxy, located in the constellation of Boötes (The Herdsman, https://goo.gl/AQKKvX), about 240 million light-years away from Earth.

NGC 5559 is a typical spiral galaxy (https://goo.gl/D3uAeP) with visible arms and ongoing star formation (https://goo.gl/Mn2Zxf).

In 2001 NGC 5559 was home to supernova 2001co, a calcium-rich supernova (https://goo.gl/4Q6HpA). Only 15 supernovae have to date been classified as this type, they are less luminous than other types of supernovae and have a quick cycle of gaining brightness and fading away.

NGC 5559 was discovered April 10th, 1785, by the English astronomer William Herschel (https://goo.gl/E9YsKH).

More information here:
https://www.spacetelescope.org/images/potw1736a/

More on the morphological classification of galaxies:
https://en.wikipedia.org/wiki/Galaxy_morphological_classification

Image credit: NGC 5559 ESA/Hubble & NASA https://goo.gl/yaYFQ6 CC BY 4.0 https://goo.gl/hNRHCd

Thank you for your interest in this Astronomy/Astrophysics collection. Maybe add me on Google+ (+Pierre Markuse) and Twitter (https://twitter.com/Pierre_Markuse) or have a look at the Space/Space Technology collection here: https://goo.gl/5KP0wx

#science #astronomy #astrophysics #ngc5559 #galaxy #spiralgalaxy #supernova #space #hubble #hst
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Water Megamaser

In this image, taken by the Hubble Space Telescope, you can see MCG+01-38-004 and MCG+01-38-005, two galaxies located in the constellation of Virgo (The Virgin, https://goo.gl/jNrR2G), about 400 million light-years away from Earth.

The blue-tinted bottom one is what is called a megamaser (https://goo.gl/kqiYAZ). The galaxy's center is an active galactic nucleus (https://goo.gl/JE6PK7), most likely powered by a supermassive black hole (https://goo.gl/eQNC6O). The immense amounts of radiation from this active galactic nucleus are stimulating clouds of surrounding water, the hydrogen and oxygen in the water absorb some of the radiation and re-emit it at specific wavelengths, including microwaves (https://goo.gl/ozkaQl). This type of megamaser is called a water megamaser.

Those strong microwave emissions are useful to determine an exact value for the Hubble Constant (https://goo.gl/14pva3).

More information here:
https://www.spacetelescope.org/images/potw1735a/

Image credit: MCG+01-38-004 and MCG+01-38-005 ESA/Hubble & NASA https://goo.gl/cohQiu CC BY 4.0 https://goo.gl/hNRHCd

Thank you for your interest in this Astronomy/Astrophysics collection. Maybe add me on Google+ (+Pierre Markuse) and Twitter (https://twitter.com/Pierre_Markuse) or have a look at the Space/Space Technology collection here: https://goo.gl/5KP0wx

#science #astronomy #astrophysics #megamaser #watermegamaser #space #hubble #hst #agn
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Comments on a post-to-post basis

A few days ago I was talking about the quality of the comments here on Google+ (https://plus.google.com/u/0/+PierreMarkuse/posts/HZFbcpQLwB1) and how I'm unable to weed out all the troll and nonsense comments. Please also read this http://www.popsci.com/science/article/2013-09/why-were-shutting-our-comments to understand why low-quality and factually wrong comments can be detrimental.

So from now on I will decide on a post-to-post basis, whether a post needs its comment section open or not. I might also keep the comments on some posts open only for a day or two. I don't really like to have to do this and miss the old days of Google+, when the comment section usually was a far more pleasant experience.

If you have a question on one of the posts with its comment section closed, you can add me on Twitter here https://twitter.com/Pierre_Markuse and send me a direct message.

Image credit: Tilted head cat by Danielle Vernon

#comments #troll #trolls #google+ #meta
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