(via APOD: 2013 May 14 - Galaxy Collisions: Simulation vs Observations)

Images Credit: NASAESAVisualization: Frank Summers (STScI); Simulation: Chris Mihos (CWRU) & Lars Hernquist (Harvard).

Intersperse computer simulation of a galaxy collision with actual Hubble images of galaxies mid-collision and you get the feeling we know, pretty well, what happens when galaxies collide.

This is important because it means we’ve got a good handle on the larger-structure evolution of the universe at the galaxy level. We need to be sure of this if we’re going to do thought experiments, make theories, and test with observations into the ancient universe what it should look like in the past.

(via APOD: 2013 February 20)
Saturn’s Hexagon and Rings
Image Credit: NASA/JPL-Caltech/Space Science Institute (Cassini spacecraft)
Nobody’s really sure why Saturn’s north pole has this very stable hexagonal structure in the clouds.
Add to that beautiful mystery the image of the shadow cast across the ring structure in the background.
And, to top it all off (rimshot!), the polar clouds, the small circular bit right at the center of of everything, have this crazy look:

Click the image or here to see the full size of the vortex: http://apod.nasa.gov/apod/ap121204.html
That hexagon has been there since Voyager flew by, and Cassini was capturing images of it in infrared before the Sun rose on the pole.
Amazing!

(via APOD: 2013 February 20)

Saturn’s Hexagon and Rings

Image Credit: NASA/JPL-Caltech/Space Science Institute (Cassini spacecraft)

Nobody’s really sure why Saturn’s north pole has this very stable hexagonal structure in the clouds.

Add to that beautiful mystery the image of the shadow cast across the ring structure in the background.

And, to top it all off (rimshot!), the polar clouds, the small circular bit right at the center of of everything, have this crazy look:

Click the image or here to see the full size of the vortex: http://apod.nasa.gov/apod/ap121204.html

That hexagon has been there since Voyager flew by, and Cassini was capturing images of it in infrared before the Sun rose on the pole.

Amazing!

(via APOD: 2013 February 6)
The Arms of M106
Credit: Image Data - Hubble Legacy Archive, Robert Gendler, Jay Gabany, Processing - Robert Gendler
Two massive jets of hydrogen gas spiral “wrong” in relation to the motion of the rest M106’s spiral arms. The others show typical dust lanes, blue star cluster, pink star forming regions, and a central yellow area with older stars. The two tendrils spinning up and down are being blown out by the energy jets coming from the galaxy’s central supermassive black hole.

(via APOD: 2013 February 6)

The Arms of M106

Credit: Image Data - Hubble Legacy Archive, Robert Gendler, Jay Gabany, Processing - Robert Gendler

Two massive jets of hydrogen gas spiral “wrong” in relation to the motion of the rest M106’s spiral arms. The others show typical dust lanes, blue star cluster, pink star forming regions, and a central yellow area with older stars. The two tendrils spinning up and down are being blown out by the energy jets coming from the galaxy’s central supermassive black hole.

(via APOD: 2013 February 3)
LL Ori and the Orion Nebula
Image Credit: NASA, ESA, and The Hubble Heritage Team
LL Orionis is a variable star (hence the “LL” designation) in the Orion nebula. It is a young star, with a more powerful solar wind than the Sun, and the shockwave at the front is due to it’s motion against the gas flowing slowly away from the hot central Trapezium cluster of stars.
Pretty much the entire Orion Nebula is full of these flows, shockwaves, and strange, fluid shapes. You can see it too! Well, OK, you can see it as a rather pink star in the scabbard stars hanging from Orion’s belt. You’ll need a good telescope to see the actual nebulosity of it.

(via APOD: 2013 February 3)

LL Ori and the Orion Nebula

Image Credit: NASAESA, and The Hubble Heritage Team

LL Orionis is a variable star (hence the “LL” designation) in the Orion nebula. It is a young star, with a more powerful solar wind than the Sun, and the shockwave at the front is due to it’s motion against the gas flowing slowly away from the hot central Trapezium cluster of stars.

Pretty much the entire Orion Nebula is full of these flows, shockwaves, and strange, fluid shapes. You can see it too! Well, OK, you can see it as a rather pink star in the scabbard stars hanging from Orion’s belt. You’ll need a good telescope to see the actual nebulosity of it.

(via APOD: 2013 February 2 - Herschel’s Andromeda)
Image Credit: ESA/Herschel/PACS & SPIRE Consortium, O. Krause, HSC, H. Linz
Herschel Space Observatory is the ESA’s amazing infrared telescope. Like NASA’s Spitzer Space Telescope, it is capable of seeing cooler (literally, as in lower temperatures) things in the universe. In this case, the dust lanes of our Local Group partner, M31, the Andromeda Galaxy. The redder material in the outskirts is quite cool, barely warmed above absolute zero by the sparse numbers of stars, while the blues in the center show hot dust energized by the crowd of stars in the core of the galaxy.
The dust itself can be used to trace molecular gas as well (both are usually found together in cool clouds) and show how much star formation is possible in Andromeda. These clouds of gas and dust tend to get shocked by supernovae or passing stars and start condensing and collapsing to form new generations of stars.

(via APOD: 2013 February 2 - Herschel’s Andromeda)

Image Credit: ESA/Herschel/PACS & SPIRE Consortium, O. Krause, HSC, H. Linz

Herschel Space Observatory is the ESA’s amazing infrared telescope. Like NASA’s Spitzer Space Telescope, it is capable of seeing cooler (literally, as in lower temperatures) things in the universe. In this case, the dust lanes of our Local Group partner, M31, the Andromeda Galaxy. The redder material in the outskirts is quite cool, barely warmed above absolute zero by the sparse numbers of stars, while the blues in the center show hot dust energized by the crowd of stars in the core of the galaxy.

The dust itself can be used to trace molecular gas as well (both are usually found together in cool clouds) and show how much star formation is possible in Andromeda. These clouds of gas and dust tend to get shocked by supernovae or passing stars and start condensing and collapsing to form new generations of stars.

(via APOD: 2012 October 30)
Planetary Nebula PK 164 +31.1
Image Credit & Copyright: Descubre Foundation, CAHA, OAUV, DSA, Vicent Peris (OAUV), Jack Harvey (SSRO), PixInsight
A planetary nebula is particularly mis-named, but, since astronomers like to cling to tradition (hence stuff having names, and Messier numbers, and NGC numbers, or maybe vdB numbers, or Abell numbers…etc.), we still call the death throes of a star a “planetary nebula”.
The hot, dense white dwarf at the center of this ball of expanding gas (the blue thing dead-center) is all that is left after a series of novas that released the outer layers of gas from the star that used to be a red giant.
From the APOD page:
“This deep image of PK 164 +31.1 from the Calar Alto Observatory in Spain shows many other stars from our own Milky Way Galaxy as well as several galaxies far in the distance. PK 164 +31, also known as Jones-Emberson 1, lies about 1,600 light years away toward the constellation of the Wildcat (Lynx). Due to its faintness (magnitude 17) and low surface brightness, the object is only visible with a good-sized telescope. Although the expanding nebula will fade away over the next few thousand years, thecentral white dwarf may well survive for billions of years”

(via APOD: 2012 October 30)

Planetary Nebula PK 164 +31.1

Image Credit & Copyright: Descubre FoundationCAHAOAUVDSA, Vicent Peris (OAUV), Jack Harvey (SSRO), PixInsight

A planetary nebula is particularly mis-named, but, since astronomers like to cling to tradition (hence stuff having names, and Messier numbers, and NGC numbers, or maybe vdB numbers, or Abell numbers…etc.), we still call the death throes of a star a “planetary nebula”.

The hot, dense white dwarf at the center of this ball of expanding gas (the blue thing dead-center) is all that is left after a series of novas that released the outer layers of gas from the star that used to be a red giant.

From the APOD page:

This deep image of PK 164 +31.1 from the Calar Alto Observatory in Spain shows many other stars from our own Milky Way Galaxy as well as several galaxies far in the distance. PK 164 +31, also known as Jones-Emberson 1, lies about 1,600 light years away toward the constellation of the Wildcat (Lynx). Due to its faintness (magnitude 17) and low surface brightness, the object is only visible with a good-sized telescope. Although the expanding nebula will fade away over the next few thousand years, thecentral white dwarf may well survive for billions of years”

(via APOD: 2013 January 2)
The Einstein Cross Gravitational Lens
Image Credit & Copyright: J. Rhoads (Arizona State U.) et al., WIYN, AURA, NOAO, NSF
What happens when a bright quasar is situated right behind the massive nucleus of a foreground galaxy? A duplication effect is created as light from the quasar is bent by relativistic gravitational lensing, creating an Einstein Cross. The relative position and brightness of the quasar can be changed by the mass distribution in the galaxy, even creating delays of entire days as the light moves around.
This example of light being lensed around a massive elliptical galaxy comes from the Subaru Telescope:

PG 1115+080: A Gravitational Cloverleaf Credit: CISCO, Subaru 8.3-m Telescope, NAOJ
In the case of the Einstein Cross here, though, the galaxy is a spiral, and, interestingly, the intervening dust in the galaxy itself does not significantly shift the light of the quasar through scattering. Amusingly, this configuration was noted because a sky survey found a low redshift galaxy whose nucleus seemed to be exactly like that of a high redshift quasar - based on the spectroscopy. Also of interest, the individual stars in the galaxy can create noticeable shifts in the brightness of the quasar through microlensing effects. Overall, they are much smaller than the effect of the whole galaxy, but they do create fluctuations that can be detected.

(via APOD: 2013 January 2)

The Einstein Cross Gravitational Lens

Image Credit & Copyright: J. Rhoads (Arizona State U.) et al., WIYNAURANOAONSF

What happens when a bright quasar is situated right behind the massive nucleus of a foreground galaxy? A duplication effect is created as light from the quasar is bent by relativistic gravitational lensing, creating an Einstein Cross. The relative position and brightness of the quasar can be changed by the mass distribution in the galaxy, even creating delays of entire days as the light moves around.

This example of light being lensed around a massive elliptical galaxy comes from the Subaru Telescope:

PG 1115+080: A Gravitational Cloverleaf 
Credit: CISCOSubaru 8.3-m TelescopeNAOJ

In the case of the Einstein Cross here, though, the galaxy is a spiral, and, interestingly, the intervening dust in the galaxy itself does not significantly shift the light of the quasar through scattering. Amusingly, this configuration was noted because a sky survey found a low redshift galaxy whose nucleus seemed to be exactly like that of a high redshift quasar - based on the spectroscopy. Also of interest, the individual stars in the galaxy can create noticeable shifts in the brightness of the quasar through microlensing effects. Overall, they are much smaller than the effect of the whole galaxy, but they do create fluctuations that can be detected.

(via APOD: 2013 January 1)
A Double Star Cluster Image Credit & Copyright: F. Antonucci, M. Angelini, & F. Tagliani, ADARA Astrobrallo
7,000 light-years away, this pair of open star clusters are actually close to each other. Frequently, these kinds of conjunctions are illusions based on the lack of perceived depth on the sky, but in this case, that’s not what’s going on. This pair of clusters in Perseus is only separated by a few hundred light-years and their stars are around the same ages, meaning that they probably both formed out of the same interstellar gas and dust in an old star forming region, like this one in the Small Magellanic Cloud:

Young Stars of NGC 346 Credit: Antonella Nota (ESA/STScI) et al., ESA, NASA

(via APOD: 2013 January 1)

A Double Star Cluster 
Image Credit & Copyright: F. Antonucci, M. Angelini, & F. Tagliani, ADARA Astrobrallo

7,000 light-years away, this pair of open star clusters are actually close to each other. Frequently, these kinds of conjunctions are illusions based on the lack of perceived depth on the sky, but in this case, that’s not what’s going on. This pair of clusters in Perseus is only separated by a few hundred light-years and their stars are around the same ages, meaning that they probably both formed out of the same interstellar gas and dust in an old star forming region, like this one in the Small Magellanic Cloud:

Young Stars of NGC 346 
Credit: Antonella Nota (ESA/STScIet al.ESANASA

(via APOD: 2012 December 31)
Saturn’s Rings from the Dark Side Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA
Cassini took this shot with the Sun shining on the rings, but the spacecraft caught the “unlit” side. We usually see the side the Sun is hitting here on Earth. The rings are, oddly, like a photographic negative of their lit side. The wide black band corresponds to the wide, usually bright, B-ring structure.
Harder to see Tethys, in the upper left, is, however, much more massive than the entire ring system.

(via APOD: 2012 December 31)

Saturn’s Rings from the Dark Side 
Image Credit: Cassini Imaging TeamSSIJPLESANASA

Cassini took this shot with the Sun shining on the rings, but the spacecraft caught the “unlit” side. We usually see the side the Sun is hitting here on Earth. The rings are, oddly, like a photographic negative of their lit side. The wide black band corresponds to the wide, usually bright, B-ring structure.

Harder to see Tethys, in the upper left, is, however, much more massive than the entire ring system.