Day 631

Friday.

1404.1899
Fingerprints of galactic loop I on the cosmic microwave background
Liu, Mertsch, Sarkar

Investigate possible imprints of galactic FG structures such as the 'radio loops' in the derived maps of the CMB.  There is evidence for these not only at radio frequencies through their synchrotron radiation, but also at microwave frequencies where emission by dust dominates.  This suggests the mechanism is magnetic dipole radiation from dust grains enriched by metallic iron, or ferrimagnetic molecules.  This new FG identified is present at high galactic latitudes, and potentially dominates over the expected B-mode polarization signal due to primordial gravitational waves from inflation.

Science, 18 Apr 2014
An Earth-sized planet in the habitable zone of a cool star
Quintana et al

Although planets that are Earth-sized and smaller have been detected, these planets reside in orbits that are too close to their host star to allow liquid water on their surfaces.  Present the detection of Kepler-186f, a 1.11pm0.14 Earth-radius planet that is the outermost of five planets, all roughly Earth-sized, that transit a 0.47pm0.05 solar-radius star.  The intensity and spectrum of the star's radiation place Kepler-186f in the stellar habitable zone, implying that if Kepler-186f has an Earth-like atmosphere and water at its surface, then some of this water is likely to be in liquid form.

1404.4365
Stars get dizzy after lunch
Zhang, Penev

The tidal distraction of hot jupiters: because the planet's orbital angular momenta are a significant fraction of their stars' rotational angular momenta, they spin up their stars significantly while spiral lying to their deaths.  It may be possible to search for tidally-destroyed planets by looking for stars with extremely short rotational periods, then looking for remnant planet cores around those candidates, anomalies in the malt distribution, or other signatures of the recent accretion of the planet.

1404.4368
Formation, tidal evolution and habitability of the Kepler-186 system
Bolmont et al

The Kepler 186 system consists of 5 planets orbiting an early-M dwarf.  These planets have physical radii of 1.0-1.5 R_Earth and orbital periods of 4 to 130 days. The 1.1 R_Earth Kepler-186f with a period of 130 days is of particular interest.  Its insolation of roughly 0.32 S_sun places it within the liquid water habitable zone.  Present a multi-faceted study of the system.  First show that the distribution of planet masses can be roughly reproduced if the planets accreted from a high-surface density disk presumably sculpted by an earlier phase of migration.  However, simulations predict the existence of 1-2 undetected planets between planets e and f.  Present a dynamical analysis of the system including the effect of tides.  The timescale for tidal evolution is short enough that the four inner planets must have small obliquities and near-synchronous rotation rates.  Tidal evolution of Kepler-186f is slow enough that its current spin state depends on a combination of its dissipation rate and the stellar age.  Finally, study the habitability of Kepler-186f with a 1-d clement mode.  The planet's surface temperature can be raised above 273K with 0.5-5 bars of CO2, depending on the amount of N2 present.  Kepler-186f represents a case study of an Earth-sized planet in the cooler regions of the habitable zone of a cool star.

1404.4379
KOI-3278: a self-lensing binary star system
Kruse, Agol

Over 40% of sun-like stars are bound in binary or multistar systems.  Stellar remnants in edge-on binary systems can gravitationally magnify their companions, as predicted 40 years ago.  From Kepler, report the detection of such a "self-lensing" system, in which a 5-hr pulse of 0.1% amplitude occurs every orbital period.  The WD stellar remnant and its Sun-like companion orbit one other very 88.18 days, a long period for a WD-eclipsing binary.  By modeling the pulse as gravitational magnification (microlensing) long with Kepler's laws and stellar models, constrain the mass of the WD to be ~63% of the mass of the Sun.  Further study of this system, and any other discovered like it, will help to constrain the physics of WDs and binary star evolution.

1404.4521
Detection of galaxies with Gaia
de Souza, et al

Gaia mission will also observe a large number of galaxies.  In this work, intend to evaluate the number and the characteristics of the galaxies that will effectively pass the onboard selection algorithm of Gaia.  Detection of objects in Gaia will be performed in a section of the focal plane known as the Sky Mapper.  Taking into account the Video Procession Algorithm criterion of detection and considering the known light profiles of discs and bulge galaxies assess the number and the type of extra-galactic objects that will be observed by Gaia.  Show that the stellar disk population of galaxies will be very difficult to observe.  On the contrary the spheroidal component of elliptical galaxies and bulges having higher central surface brightness and steeper brightness profile will be more easy to be detected.  Estimate that most of the 20k elliptical population of nearby galaxies inside the local region up to 170 Mpc are in condition to be observed by Gaia.  A similar number of bulges could also be observed although the low luminosity bulges should escape detection.  About two thirds of the more distant objects up to 600 Mpc could also be detected increasing the total sample to half a million objects including ellipticals and bulges.  The angular size of the detected objects will never exceed 4.72 arc sec which is the size of the largest transmitted windows.  An heterogeneous population of elliptical galaxies and bulges will be observable by Gaia.  This nearby Universe sample of galaxies should constitute a very rich and ingesting sample to study their structural properties and their distribution.