Warren Huelsnitz
276 followers -
physicist, educator, designer, blogger
physicist, educator, designer, blogger
276 followers
Warren Huelsnitz's interests
Warren Huelsnitz's posts
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Ou4: A Giant Squid Nebula
Image Credit: Romano Corradi (IAC), Nicolas Grosso, Agnès Acker, Robert Greimel, Patrick Guillout
http://apod.nasa.gov/apod/ap140718.html
A mysterious, squid-like apparition, this nebula is very faint, but also very large in planet Earth's sky. In the mosaic image, composed with narrowband data from the 2.5 meter Isaac Newton Telescope, it spans some 2.5 full moons toward the constellation Cepheus. Recently discovered by French astro-imager Nicolas Outters, the remarkable nebula's bipolar shape and emission are consistent with it being a planetary nebula, the gaseous shroud of a dying sun-like star, but its actual distance and origin are unknown. A new investigation suggests Ou4 really lies within the emission region SH2-129 some 2,300 light-years away. Consistent with that scenario, the cosmic squid would represent a spectacular outflow of material driven by a triple system of hot, massive stars, cataloged as HR8119, seen near the center of the nebula. If so, this truly giant squid nebula would physically be nearly 50 light-years across.
Image Credit: Romano Corradi (IAC), Nicolas Grosso, Agnès Acker, Robert Greimel, Patrick Guillout
http://apod.nasa.gov/apod/ap140718.html
A mysterious, squid-like apparition, this nebula is very faint, but also very large in planet Earth's sky. In the mosaic image, composed with narrowband data from the 2.5 meter Isaac Newton Telescope, it spans some 2.5 full moons toward the constellation Cepheus. Recently discovered by French astro-imager Nicolas Outters, the remarkable nebula's bipolar shape and emission are consistent with it being a planetary nebula, the gaseous shroud of a dying sun-like star, but its actual distance and origin are unknown. A new investigation suggests Ou4 really lies within the emission region SH2-129 some 2,300 light-years away. Consistent with that scenario, the cosmic squid would represent a spectacular outflow of material driven by a triple system of hot, massive stars, cataloged as HR8119, seen near the center of the nebula. If so, this truly giant squid nebula would physically be nearly 50 light-years across.
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The Hercules Cluster of Galaxies
Image Credit & Copyright: Ken Crawford
http://apod.nasa.gov/apod/ap140625.html
These are galaxies of the Hercules Cluster, an archipelago of island universes a mere 500 million light-years away. Also known as Abell 2151, this cluster is loaded with gas and dust rich, star-forming spiral galaxies but has relatively few elliptical galaxies, which lack gas and dust and the associated newborn stars. The colors in this remarkably deep composite image clearly show the star forming galaxies with a blue tint and galaxies with older stellar populations with a yellowish cast. The sharp picture spans about 3/4 degree across the cluster center, corresponding to over 6 million light-years at the cluster's estimated distance. Diffraction spikes around brighter foreground stars in our own Milky Way galaxy are produced by the imaging telescope's mirror support vanes. In the cosmic vista many galaxies seem to be colliding or merging while others seem distorted - clear evidence that cluster galaxies commonly interact. In fact, the Hercules Cluster itself may be seen as the result of ongoing mergers of smaller galaxy clusters and is thought to be similar to young galaxy clusters in the much more distant, early Universe.
Image Credit & Copyright: Ken Crawford
http://apod.nasa.gov/apod/ap140625.html
These are galaxies of the Hercules Cluster, an archipelago of island universes a mere 500 million light-years away. Also known as Abell 2151, this cluster is loaded with gas and dust rich, star-forming spiral galaxies but has relatively few elliptical galaxies, which lack gas and dust and the associated newborn stars. The colors in this remarkably deep composite image clearly show the star forming galaxies with a blue tint and galaxies with older stellar populations with a yellowish cast. The sharp picture spans about 3/4 degree across the cluster center, corresponding to over 6 million light-years at the cluster's estimated distance. Diffraction spikes around brighter foreground stars in our own Milky Way galaxy are produced by the imaging telescope's mirror support vanes. In the cosmic vista many galaxies seem to be colliding or merging while others seem distorted - clear evidence that cluster galaxies commonly interact. In fact, the Hercules Cluster itself may be seen as the result of ongoing mergers of smaller galaxy clusters and is thought to be similar to young galaxy clusters in the much more distant, early Universe.
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Hole in One
Recently there’s been news that scientists suspect the black hole in the center of our galaxy may be a wormhole instead. Needless to say, you shouldn’t get your hopes up. The news is actually based on a preprint published on the arxiv that outlines how one might distinguish between a black hole and a hypothetical “white hole”.
Wormholes are an idea that show up every now and then in the literature. They originally appeared as an extension of black hole solutions past the singularity as a kind of misguided mathematics. They were originally known as Einstein-Rosen bridges, but it didn’t take long for the term “wormhole” to become popular. Technically, they are a possible solution within general relativity, but theoretical studies soon showed there was no way for them to be traversable without some kind of “exotic matter”. Later it was found that some theoretical extensions of general relativity could allow for wormholes without exotic matter, so there’s been some work to determine whether they would have any visible effect.
Basically that’s the topic of this particular paper. The authors start by supposing that wormholes can exist through some extension of general relativity, and then ask whether this is some way to distinguish between an ordinary black hole and a wormhole. What they find is that the mouth of a wormhole (a white hole) would look very similar to a rotating black hole, but the way it affects material near it would be different. Basically the frame dragging effects are different. This means that any hot gases near a black hole or white hole would be distorted in different ways.
By itself, the paper is simply a “what if” scenario where theorists push the limits of a theory to better understand different models. But in this case the authors note that the resolution needed to distinguish between these two models is something achievable for the supermassive black hole in the center of the Milky Way. In a couple years the Very Large Telescope Interferometer (VLTI) will begin its GRAVITY project, which will utilize adaptive optics, and this could give us enough detail to distinguish between a black hole and a white hole.
No one seriously thinks the supermassive black hole in our galaxy is actually a wormhole, or even that wormholes are actually possible. But it’s interesting to see that such a wild idea could be testable in a few years.
Image: ESO/M. Kornmesser
Paper: Zilong Li and Cosimo Bambi. Distinguishing black holes and wormholes with orbiting hot spots. arXiv:1405.1883 [gr-qc] (2014)
Recently there’s been news that scientists suspect the black hole in the center of our galaxy may be a wormhole instead. Needless to say, you shouldn’t get your hopes up. The news is actually based on a preprint published on the arxiv that outlines how one might distinguish between a black hole and a hypothetical “white hole”.
Wormholes are an idea that show up every now and then in the literature. They originally appeared as an extension of black hole solutions past the singularity as a kind of misguided mathematics. They were originally known as Einstein-Rosen bridges, but it didn’t take long for the term “wormhole” to become popular. Technically, they are a possible solution within general relativity, but theoretical studies soon showed there was no way for them to be traversable without some kind of “exotic matter”. Later it was found that some theoretical extensions of general relativity could allow for wormholes without exotic matter, so there’s been some work to determine whether they would have any visible effect.
Basically that’s the topic of this particular paper. The authors start by supposing that wormholes can exist through some extension of general relativity, and then ask whether this is some way to distinguish between an ordinary black hole and a wormhole. What they find is that the mouth of a wormhole (a white hole) would look very similar to a rotating black hole, but the way it affects material near it would be different. Basically the frame dragging effects are different. This means that any hot gases near a black hole or white hole would be distorted in different ways.
By itself, the paper is simply a “what if” scenario where theorists push the limits of a theory to better understand different models. But in this case the authors note that the resolution needed to distinguish between these two models is something achievable for the supermassive black hole in the center of the Milky Way. In a couple years the Very Large Telescope Interferometer (VLTI) will begin its GRAVITY project, which will utilize adaptive optics, and this could give us enough detail to distinguish between a black hole and a white hole.
No one seriously thinks the supermassive black hole in our galaxy is actually a wormhole, or even that wormholes are actually possible. But it’s interesting to see that such a wild idea could be testable in a few years.
Image: ESO/M. Kornmesser
Paper: Zilong Li and Cosimo Bambi. Distinguishing black holes and wormholes with orbiting hot spots. arXiv:1405.1883 [gr-qc] (2014)
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Wonderful APOD! - CG4: A Ruptured Cometary Globule
Image Credit & Copyright: Jason Jennings (cosmicphotos)
Image Credit & Copyright: Jason Jennings (cosmicphotos)
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Inside the Flame Nebula
Image Credit: Optical: DSS; Infrared: NASA/JPL-Caltech;
X-ray: +NASA/CXC/PSU/ K.Getman, E.Feigelson, M.Kuhn & the MYStIX team
http://apod.nasa.gov/apod/ap140510.html
The Flame Nebula stands out in this optical image of the dusty, crowded star forming regions toward Orion's belt, a mere 1,400 light-years away. X-ray data from the Chandra Observatory and infrared images from the Spitzer Space Telescope can take you inside the glowing gas and obscuring dust clouds though. Swiping your cursor (or clicking the image) will reveal many stars of the recently formed, embedded cluster NGC 2024, ranging in age from 200,000 years to 1.5 million years young. The X-ray/infrared composite image overlay spans about 15 light-years across the Flame's center. The X-ray/infrared data also indicate that the youngest stars are concentrated near the middle of the cluster. That's the opposite of the simplest models of star formation for the stellar nursery. They predict star formation to begin first in the denser center and progressively move outward toward the edges leaving the older stars, not the younger ones, in the center of the Flame Nebula.
Image Credit: Optical: DSS; Infrared: NASA/JPL-Caltech;
X-ray: +NASA/CXC/PSU/ K.Getman, E.Feigelson, M.Kuhn & the MYStIX team
http://apod.nasa.gov/apod/ap140510.html
The Flame Nebula stands out in this optical image of the dusty, crowded star forming regions toward Orion's belt, a mere 1,400 light-years away. X-ray data from the Chandra Observatory and infrared images from the Spitzer Space Telescope can take you inside the glowing gas and obscuring dust clouds though. Swiping your cursor (or clicking the image) will reveal many stars of the recently formed, embedded cluster NGC 2024, ranging in age from 200,000 years to 1.5 million years young. The X-ray/infrared composite image overlay spans about 15 light-years across the Flame's center. The X-ray/infrared data also indicate that the youngest stars are concentrated near the middle of the cluster. That's the opposite of the simplest models of star formation for the stellar nursery. They predict star formation to begin first in the denser center and progressively move outward toward the edges leaving the older stars, not the younger ones, in the center of the Flame Nebula.
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"Orion: Head to Toes" by Rogelio Bernal Andreo
Spanning nearly 25 degrees, this 32 pane mosaic vista stretches across the well-known constellation of Orion, from head (top) to toe (bottom). Captured with a Takahashi FSQ telescope and STL11000 camera in October 2010
Credit: Rogelio Bernal Andreo
Rogelio's website: www.deepskycolors.com
+Rogelio Bernal Andreo
#Space #Astronomy #Nebula #Orion #Belt #M42 #Night #Sky #Astrophotography #Art #Science #Panorama #Mosaic
Spanning nearly 25 degrees, this 32 pane mosaic vista stretches across the well-known constellation of Orion, from head (top) to toe (bottom). Captured with a Takahashi FSQ telescope and STL11000 camera in October 2010
Credit: Rogelio Bernal Andreo
Rogelio's website: www.deepskycolors.com
+Rogelio Bernal Andreo
#Space #Astronomy #Nebula #Orion #Belt #M42 #Night #Sky #Astrophotography #Art #Science #Panorama #Mosaic
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Papers Please
The BICEP2 paper has officially been accepted in Physical Review Letters. Having survived peer review, does that mean we can now declare that inflation has now been officially observed? Not necessarily.
You might remember the ongoing saga of the BICEP2 results, from the first press release announcing the detection of B-mode polarization within the cosmic microwave background. There are several sources of this kind of polarization, but one of them is inflation in the early universe. The announcement made headlines everywhere, but also stirred a great deal of controversy. It didn’t take long for “peer review” to start pushing back on the results. First was evidence that interstellar dust could create B-mode polarization in addition to other sources. Then results from the Planck satellite were released with some dust polarization results. Then came news that the BICEP2 team had used some “reverse engineered” data from a Planck result, that some argued invalidated the results.
As I’ve pointed out in earlier posts, these kinds of hard hitting attacks are part of what peer review is all about. The fact that it occurs publicly has more do to with the publicity of science rather than some failure in the process. But behind all the public drama over the results, there has been the real academic process of peer review. The BICEP2 team submitted their paper to Physical Review, and the paper has been accepted with some changes. It has officially survived the process that I often tout as the gold standard of science.
Does that mean the BICEP2 team has won? In a way, they have. Surviving peer review is no small feat, particularly for a controversial result such as early inflation. But the revision of their paper is also significant. In particular, the paper admits that their result might not be a real signal of inflation after all. From the abstract, they state:
However, these models are not sufficiently constrained by external public data to exclude the possibility of dust emission bright enough to explain the entire excess signal.
So they have a real observation of B-mode polarization, and it looks like evidence of cosmic inflation, but they can’t rule out the possibility that their signal is just due to interstellar dust. They also state that more data will be needed to answer that question.
This is what peer review gives us. The BICEP2 team made bold initial claims, and they were taken to task. Much of their initial claims have survived the process, but their bold claim has given way to a more cautious result. They got a paper out of the work, but they also had to eat a bit of crow, and that’s never easy.
But what we get in return is a better understanding of the universe.
Paper: P. A. R. Ade, et al. Detection of B-Mode Polarization at Degree Angular Scales by BICEP2. PRL 112, 241101 (2014).
The BICEP2 paper has officially been accepted in Physical Review Letters. Having survived peer review, does that mean we can now declare that inflation has now been officially observed? Not necessarily.
You might remember the ongoing saga of the BICEP2 results, from the first press release announcing the detection of B-mode polarization within the cosmic microwave background. There are several sources of this kind of polarization, but one of them is inflation in the early universe. The announcement made headlines everywhere, but also stirred a great deal of controversy. It didn’t take long for “peer review” to start pushing back on the results. First was evidence that interstellar dust could create B-mode polarization in addition to other sources. Then results from the Planck satellite were released with some dust polarization results. Then came news that the BICEP2 team had used some “reverse engineered” data from a Planck result, that some argued invalidated the results.
As I’ve pointed out in earlier posts, these kinds of hard hitting attacks are part of what peer review is all about. The fact that it occurs publicly has more do to with the publicity of science rather than some failure in the process. But behind all the public drama over the results, there has been the real academic process of peer review. The BICEP2 team submitted their paper to Physical Review, and the paper has been accepted with some changes. It has officially survived the process that I often tout as the gold standard of science.
Does that mean the BICEP2 team has won? In a way, they have. Surviving peer review is no small feat, particularly for a controversial result such as early inflation. But the revision of their paper is also significant. In particular, the paper admits that their result might not be a real signal of inflation after all. From the abstract, they state:
However, these models are not sufficiently constrained by external public data to exclude the possibility of dust emission bright enough to explain the entire excess signal.
So they have a real observation of B-mode polarization, and it looks like evidence of cosmic inflation, but they can’t rule out the possibility that their signal is just due to interstellar dust. They also state that more data will be needed to answer that question.
This is what peer review gives us. The BICEP2 team made bold initial claims, and they were taken to task. Much of their initial claims have survived the process, but their bold claim has given way to a more cautious result. They got a paper out of the work, but they also had to eat a bit of crow, and that’s never easy.
But what we get in return is a better understanding of the universe.
Paper: P. A. R. Ade, et al. Detection of B-Mode Polarization at Degree Angular Scales by BICEP2. PRL 112, 241101 (2014).
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Atoms and molecules emit and absorb light only at specific wavelengths. This turns out to be one of the most useful tools for astronomers. With it we can determine the elements in a distant star, measure its speed toward or away from us, and many other things.
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Alnitak, Alnilam & Mintaka | Astronomy Picture of The Day
Alnitak, Alnilam, and Mintaka, are the bright bluish stars from east to west (lower right to upper left) along the diagonal in this gorgeous cosmic vista. Otherwise known as the Belt of Orion, these three blue supergiant stars are hotter and much more massive than the Sun. They lie about 1,500 light-years away, born of Orion's well-studied interstellar clouds. In fact, clouds of gas and dust adrift in this region have intriguing and some surprisingly familiar shapes, including the dark Horsehead Nebula and Flame Nebula near Alnitak at the lower right. The famous Orion Nebula itself is off the right edge of this colorful star field. The well-framed, wide-field telescopic image spans about 4 degrees on the sky.
Image Credit & Copyright: Rogelio Bernal Andreo (Deep Sky Colors)
+Astronomy Picture of the Day (APoD)
+Rogelio Bernal Andreo
#NASA #Space #Astronomy #Stars #Supergiant #Alnitak #Alnilam #Mintaka #Orion #Belt #Nebula #Cosmos #Universe
Alnitak, Alnilam, and Mintaka, are the bright bluish stars from east to west (lower right to upper left) along the diagonal in this gorgeous cosmic vista. Otherwise known as the Belt of Orion, these three blue supergiant stars are hotter and much more massive than the Sun. They lie about 1,500 light-years away, born of Orion's well-studied interstellar clouds. In fact, clouds of gas and dust adrift in this region have intriguing and some surprisingly familiar shapes, including the dark Horsehead Nebula and Flame Nebula near Alnitak at the lower right. The famous Orion Nebula itself is off the right edge of this colorful star field. The well-framed, wide-field telescopic image spans about 4 degrees on the sky.
Image Credit & Copyright: Rogelio Bernal Andreo (Deep Sky Colors)
+Astronomy Picture of the Day (APoD)
+Rogelio Bernal Andreo
#NASA #Space #Astronomy #Stars #Supergiant #Alnitak #Alnilam #Mintaka #Orion #Belt #Nebula #Cosmos #Universe
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Chandra Flashback of the Day – 3C321: Black Hole Fires at Neighboring Galaxy
http://chandra.harvard.edu/photo/2007/3c321/
http://chandra.harvard.edu/photo/2007/3c321/
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