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Jay Cross
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Attended Rensselaer Polytechnic Institute
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Astronomy Papers That Caught Fred's Eye In Today's arXiv

These are the Friday papers.
 
"Eye-catching" papers submitted to astro-archives today (Friday).

Topics selected include Dark Matter, The James Webb Telescope, Cosmic Ray origins, Planetary Rings, VLBI, Crowdfunding

Milking the spherical cow: on aspherical dynamics in spherical coordinates http://arxiv.org/abs/1502.07356 We have had some fun with 'round cow' assumptions on this thread; this paper looks at the differences between 'real dark matter' and 'round cow' approximations.

James Webb Space Telescope can Detect Kilonovae in Gravitational Wave Follow-up Search http://arxiv.org/abs/1502.07426 What surprised me the most about this paper is that the launch date for the James Webb Space Telescope has been pushed out to at least 2018; and the Advanced Ligo Gravitational Wave telescope is not expected to be operating at optimum sensitivity until 2019.

* A minimal width of the arrival direction distribution of ultra-high energy cosmic rays detected with the Yakutsk array* http://arxiv.org/abs/1502.07496 This paper supports recent announcements that cosmic rays arrive from fairly compact source 'areas'; but on the narrowest of scales, we are still a ways from pinning them down.

Why are dense planetary rings only found between 8 AU and 20 AU? http://arxiv.org/abs/1502.07696 This seemingly obvious question has an equally obvious answer, but has anyone really ask it; or answered it before?

The deflection of light induced by the Sun's gravitational field and measured with geodetic VLBI http://arxiv.org/abs/1502.07395 The authors claim an explicit proof of General Relativity using VLBI data; but one aspect of the proof is very troubling to me. From the authors: "In addition, the coordinate term explicitly presented in the conventional geometric delay model ceases to exist because it is compensated by the same effect in the gravitational delay with the opposite sign."

All well and good, but wouldn't this exact cancelation be manifest by any similarly contrived pairs of phenomena, and wouldn't there be the same results if their were no off-setting effects at all? (There is a similar cancelation of General Relativistic mass effects between polar and equatorial masses.)

Crowdfunding Astronomy with Google Sky http://arxiv.org/abs/1502.07393
Abstract: Galaxies and the dark matter halos that host them are not spherically symmetric, yet spherical symmetry is a helpful simplifying approximation for idealised calculations and analysis of observational data. The assumption leads to an exact conservation of angular momentum for every ...
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Look at the huge circular region on the left image at the lower half of Ceres. There is a modest sized crater surrounded by a huge circular flat plain, with four other craters roughly evenly spaced on that plain. This is a relatively recent feature because there aren't many craters on the plain. I wonder what could have caused this.
Bild des Tages Zwergplanet Ceres, von der Raumsonde Dawn am 19. Februar 2015 aus einer Entfernung von etwa 46.000 km aufgenommen. (Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)
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Astronomy Papers That Caught My Eye In Today's arXiv

There are 67 papers today (Tuesday), not counting replacements. 

Topics: PAPER-64, Gaia-LSST Synergy, Propulsion Methods To Mars

PAPER-64 http://arxiv-web3.library.cornell.edu/abs/1502.06016 PAPER-64 is a South African radio telescope array or 64 radio telescopes which is being used to observe 21cm radiation that has been redshifted to almost 2 meter wavelengths (z=8.4). This paper looks at the time of reionization with new cleaner signal than any previous effort.

Gaia-LSST Synergy http://arxiv-web3.library.cornell.edu/abs/1502.06555 LSST isn't built yet, but it is coming. The Gaia data is being collected, but hasn't been published yet. This paper looks at how LSST is going to benefit from the data methods that will be used to process Gaia data with the LSST data that goes 5 magnitudes deeper.

Propulsion Methods To Mars http://arxiv-web3.library.cornell.edu/abs/1502.06457 There are several possible unbuilt and untested propulsion methods that might get used for getting men to Mars. How do they compare? This entertaining paper compares them.
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+Aaron Macks Nuclear thermal is different from an RTG. An RTG uses a dumb lump of a radioactive substance undergoing natural decay to produce heat, and then produces power from that heat.

Nuclear thermal propulsion is a propulsion system that uses a fission reactor - a complex mechanism that uses a controlled chain reaction to produce power. This reactor produces heat which heats up hydrogen propellant for thrust.

Compared to radioisotope power generation, a fission reactor is for more powerful, and it can be throttled. Radioactive decay can't be accelerated or halted in any way, so the lump of material produces a steady amount of heat regardless of how much you want.

A fission reactor uses a neutron moderating control rods to either open up or shut down the chain reaction. It's more complex than an RTG, but it produces far more power.
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Astronomy Papers That Caught My Eye In Today's arXiv

There are 43 papers today (Monday), not counting replacements. 

Topics: Simulating SMBH Destroying Stars, VHE Gammas From Novae, SMBH Binaries and eLISA

Simulating SMBH Destroying Stars http://arxiv.org/abs/1502.05740 So what happens when a star gets tidally disrupted by a supermassive black hole? An accretion disk forms and material accretes into the black hole, and it is very bright for a while. How long does this take? How long does it stay bright? We don't know. This simulation tries to get some answers.

VHE Gammas From Novae http://arxiv.org/abs/1502.05853 There have been a few Novae and Dwarf Novae in the galactic neighborhood since the launching of Fermi-LAT and the building of MAGIC. This has provided an opportunity to study the very high energy gamma rays coming from these objects, and to make better models for how these > TeV gammas are made.

SMBH Binaries and eLISA http://arxiv.org/abs/1502.05735 eLISA is an upcoming mission to have an array of probes measuring Gravitational Waves. This paper looks at what should be seeable in the way of GWs from binary SMBHs in the distant universe.
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As usual, when we are unusually cold, Siberia is unusually warm.
 
Temperature anomaly map for Feb 20.  Yep, US east, you are in a minority, with that big blue-purple blob...
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Poor Irkutsk! It's not warm at the best of times...
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Astronomy Papers That Caught Fred's Eye In Today's arXiv

These are the Thursday papers.
 
"Eye-catching" papers submitted to Astro-archives today.

 *The topic de jour is the sun*, there are also articles selected on stars being eaten by AGN and a possible supernova progenitor.

The Solar Cycle http://arxiv.org/abs/1502.07020 This is a review article - looking at periodic solar effects

Ultra-high-resolution Observations of MHD Waves in Photospheric Magnetic Structures http://arxiv.org/abs/1502.06960 If there is one most vexing question I would like to know the answer to, it is why the solar corona is so much hotter than the surface of the sun. This paper looks at the finest known electromagnetic resolution, and hints at a solution. (One that includes sausage waves with kinks in them.) See also http://arxiv.org/abs/1502.07213 Non-linear propagation of kink waves to the solar chromosphere
also
X-ray and EUV Observations of Simultaneous Short and Long Period Oscillations in Hot Coronal Arcade Loops
http://arxiv.org/abs/1502.07117

*Multiple tidal disruption flares in the active galaxy IC 3599 * http://arxiv.org/abs/1502.07184 It is pretty much a given that active galactic nuclei have the ability to rip apart stars the same way the sun tears the heart out of comets. This periodic flaring of IC 3599 may be the death throws of a star in a dying elliptical orbit.

HD188112: Supernova Ia progenitor? http://arxiv.org/abs/1502.07096 It is the right size and appears to have a companion, now all we need to see it do is up and explode with a tenth of the brilliance of an entire galaxy.
Abstract: The Solar Cycle is reviewed. The 11-year cycle of solar activity is characterized by the rise and fall in the numbers and surface area of sunspots. A number of other solar activity indicators also vary in association with the sunspots including; the 10.7cm radio flux, the total solar ...
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Astronomy Papers That Caught My Eye In Today's arXiv

There are 55 papers today (Wednesday), not counting replacements. 

Topics: SOFIA/EXES, Spectra of KBOs, Quark Nova

SOFIA/EXES http://arxiv.org/abs/1502.06611 Remember all the stories about the Infrared telescope that was going to fly in a jet that could open on the side? The telescope is called SOFIA, and it is in use. Sometimes there are papers about what it observes. his one is about high resolution spectrography of water in a protostar. I'm interested in seeing what this instrument can do.

Spectra of KBOs http://arxiv.org/abs/1502.06612 Hubble's Wide Field Camera 3 was used to look at 12 KBOs to look at the optical and near infrared colors to see how much variation there was. The results give a new more refined look at the classes of these objects.

Quark Nova http://arxiv.org/abs/1502.06892 Supernova SN DES13S2cmm was overly luminous. There are hints in the specrum that it may have been a Quark Nova. Details are kind of interesting.
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You can follow +SOFIA Telescope here on Google+.
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Astronomy Papers That Caught My Eye In Today's arXiv

There are 55 papers today (Wednesday), not counting replacements. 

Topics: SOFIA/EXES, Spectra of KBOs, Quark Nova

SOFIA/EXES http://arxiv.org/abs/1502.06611 Remember all the stories about the Infrared telescope that was going to fly in a jet that could open on the side? The telescope is called SOFIA, and it is in use. Sometimes there are papers about what it observes. his one is about high resolution spectrography of water in a protostar. I'm interested in seeing what this instrument can do.

Spectra of KBOs http://arxiv.org/abs/1502.06612 Hubble's Wide Field Camera 3 was used to look at 12 KBOs to look at the optical and near infrared colors to see how much variation there was. The results give a new more refined look at the classes of these objects.

Quark Nova http://arxiv.org/abs/1502.06892 Supernova SN DES13S2cmm was overly luminous. There are hints in the specrum that it may have been a Quark Nova. Details are kind of interesting.
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Appreciate the info
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Astronomy Papers That Caught My Eye In Today's arXiv

There are 67 papers today (Tuesday), not counting replacements. 

Topics: PAPER-64, Gaia-LSST Synergy, Propulsion Methods To Mars

PAPER-64 http://arxiv-web3.library.cornell.edu/abs/1502.06016 PAPER-64 is a South African radio telescope array or 64 radio telescopes which is being used to observe 21cm radiation that has been redshifted to almost 2 meter wavelengths (z=8.4). This paper looks at the time of reionization with new cleaner signal than any previous effort.

Gaia-LSST Synergy http://arxiv-web3.library.cornell.edu/abs/1502.06555 LSST isn't built yet, but it is coming. The Gaia data is being collected, but hasn't been published yet. This paper looks at how LSST is going to benefit from the data methods that will be used to process Gaia data with the LSST data that goes 5 magnitudes deeper.

Propulsion Methods To Mars http://arxiv-web3.library.cornell.edu/abs/1502.06457 There are several possible unbuilt and untested propulsion methods that might get used for getting men to Mars. How do they compare? This entertaining paper compares them.
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Astronomy Papers That Caught My Eye In Today's arXiv

There are 43 papers today (Monday), not counting replacements. 

Topics: Simulating SMBH Destroying Stars, VHE Gammas From Novae, SMBH Binaries and eLISA

Simulating SMBH Destroying Stars http://arxiv.org/abs/1502.05740 So what happens when a star gets tidally disrupted by a supermassive black hole? An accretion disk forms and material accretes into the black hole, and it is very bright for a while. How long does this take? How long does it stay bright? We don't know. This simulation tries to get some answers.

VHE Gammas From Novae http://arxiv.org/abs/1502.05853 There have been a few Novae and Dwarf Novae in the galactic neighborhood since the launching of Fermi-LAT and the building of MAGIC. This has provided an opportunity to study the very high energy gamma rays coming from these objects, and to make better models for how these > TeV gammas are made.

SMBH Binaries and eLISA http://arxiv.org/abs/1502.05735 eLISA is an upcoming mission to have an array of probes measuring Gravitational Waves. This paper looks at what should be seeable in the way of GWs from binary SMBHs in the distant universe.
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Astronomy Papers That Caught Fred's Eye In Today's arXiv

These are the Friday papers.
 
"Eye-catching papers submitted to Astro-archives today (Friday)

Topics selected include: * Very distant galaxies, gamma rays, Saturn electromagnetics, Supernova 1987a, MOND, Blazers and Gamma rays*

A Spectroscopic Redshift Measurement for a Luminous Lyman Break Galaxy at z=7.730 using Keck/MOSFIRE http://arxiv.org/abs/1502.05399 http://arxiv.org/abs/1502.05399 Hubble is the astronomical gift that just keeps giving. The Near-IR package delivered by the last Space Shuttle service call is telling us more about the distant universe than many of us ever imagined. They have confirmed, spectroscopically, that there is a wealth of information out their just waiting for the James Webb telescope to reveal.

Not In Our Backyard: Spectroscopic Support for the CLASH z=11 Candidate MACS0647-JD http://arxiv.org/abs/1502.05681 Strong Identification of lensed galaxies from the very distant past are hindered by interlopers: spectral traces of closer elements possibly in the lensing system. This paper goes through the complicated series of screenings necessary to reject broad spectral elements that would otherwise greatly reduce confidence in that the z-11 distance is bonafide - yet another great James Webb telescope candidate.

Mapping High-velocity H-alpha and Lyman-alpha Emission from Supernova 1987A http://arxiv.org/abs/1502.05403 When you leave the burner of the stove on high, melt down the pan and set the house on fire, you expect that eventually the electricity will be turned off. Since 1987, the remnant of Supernova 1987a in the Small Magellanic Cloud continues to radiate at higher-than-expected levels than anyone predicted - the rings of destruction continue to fan out. When will it ever end?

The magnetic structure of Saturn's magnetosheath http://arxiv.org/abs/1502.05504 Cassini has been in orbit about Saturn for over a year now, and this paper covers the first six years of magnetic data. It is one of the most extensive papers on Alfven wave interaction with planets ever published.

Post-Newtonian constraints on khronometric gravity theories with a MOND phenomenology http://arxiv.org/abs/1502.05554 MOND is a alternative explanation for Dark Matter that has been hanging around for two decades. One of the problems with MOND, is that it is difficult to come up with a relativistic version. (This is way Dark Matter is the preferred solution: it was not predicted by General Relativity, but neither was it ruled out.) This is one of the most promising adaptations of MOND I have seen, which gives it a snowball-in-hells chance of becoming an accepted theory. You never know - Boston did win the World Series.

Awakening of The High Redshift Blazar CGRaBS J0809+5341 http://arxiv.org/abs/1502.05660 Blazers are Active Galactic Nuclei that are know to very in magnitude as they tear apart and eat galaxies, but this was one gigantic cosmic burp.

Search for GeV Gamma Ray Bursts with the ARGO-YBJ Detector: Summary of Eight Years of Observations http://arxiv.org/abs/1502.05622 If you have been following gamma ray paper for the last eight years, you probably think gamma ray data is all over the map. This paper pretty much agrees with that synopsis.
Abstract: We present a spectroscopic redshift measurement of a very bright Lyman break galaxy at z=7.7302+-0.0006 using Keck/MOSFIRE. The source was pre-selected photometrically in the EGS field as a robust z~8 candidate with H=25.0 mag based on optical non-detections and a very red Spitzer/IRAC ...
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Astronomy Papers That Caught Fred's Eye In Today's arXiv

These are the Thursday papers.
 
"Eye-Catching" papers submitted to Astro-archives today.

Topics selected include: Reionization polarization, First Science from SPHERE, Fast Radio Bursts, Gravitational Lens Timing 

New Limits on Polarized Power Spectra at 126 and 164 MHz: Relevance to Epoch of Reionization Measurements http://arxiv.org/abs/1502.05072 "New limits" is astro-speak for 'We didn't find what we were hoping to - at least not yet'. This is disappointing because there are known local sources of contamination (such as galactic cyclotron effects); so it is hoped that the dynamics of the Epoch of Reionization are great enough to rise above this local chatter.

The First Science Results from SPHERE: Disproving the Predicted Brown Dwarf around V471 Tau http://arxiv.org/abs/1502.05116 Variations in the arrival time of binary eclipses has long led to the speculation that there is a brown dwarf lurking in the system some where, throwing a wrench into the mechanics. But under the microscope, no such critter has emerged. The replacement theory to explain the anomaly is interesting: Shifts in the quadrapole of one of the parent stars.

*Fast Radio Bursts: Collisions between Neutron Stars and Asteroids/Comets * http://arxiv.org/abs/1502.05171 It is always fun to find within a paper about a new theory a concrete observable that can be used to either prove or dispel the theory. This pair of researchers hypothesize that if neutron stars gobbling up comets produces radio-loud blips, a quick follow-up observation in the x-Ray bandwidths should reveal a corresponding burp.

New Estimates of Time Delays in the Gravitationally Lensed System PG1115+080 http://arxiv.org/abs/1502.05392 Gravitationally lensed galaxies sometimes include multiple lensed systems, giving us two or more images of the same galaxy. What has been surprising is the fairly broad time delays that have been reported on the arrival time of light taking two different paths. This paper looks at delays reported in the past and irons some of them out.

*In Search of Future Earths: Assessing the possibility of finding Earth analogues in the later stages of their habitable lifetimes *
http://arxiv.org/abs/1502.05349 One of the reoccurring themes in science fiction is the search for a new home when the earth becomes too hot to support live. (In a couple billion years if we have to wait for the sun to heat up, much less if the effects of global warming are grossly underestimated.) Here is a pessimistic (meaning realistic) assessment of how close and how soon we will have an answer.
Abstract: Polarized foreground emission is a potential contaminant of attempts to measure the fluctuation power spectrum of highly redshifted 21 cm H{\sc i} emission from the epoch of reionization, yet observational constraints on the level of polarized emission are poor.
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Are cyclotron effects distinct from synchrotron radiation?
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I'm a technical trainer for enterprise software systems
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One of a long line of Renaissance Men
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Publicly, I post a lot of astronomy stuff. I also post about politics, my life, the future, and links to my photo journal to people in specific circles.

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It seems impolite for me to say all the great stuff I've been lucky enough to do.
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    Physics, 1973 - 1979
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I've gone by "antoniseb" on the web, and in the Society for Creative Anachronism, I'm called "Anton of Winteroak"