1305.2222
STIS Coronagraphic imaging of Fomalhaut: Main belt structure and the orbit of Fomalhaut b
Kalas, Graham, Fitzgerald, Clampin
Observed Fomalhaut b is recovered with optical coronagraph with HST; tenuous nebulosity beyond the main dust belt detected to at least 209 AU and a ~50 AU wide azimuthal gap north of Fom b. Fom b appears elliptical in STIS detection. Orbit of Fom b is highly eccentric with e=0.8, a=177 pm68 AU and q=32 pm24 AU. Fom b apsidally aligned with the belt and 90% of allowed orbits (from MCMC) have mutual inclination 36 deg or less. Fom b's orbit is belt-crossing in projection, but only 12% of possible orbits have nodes ithin a 25 AU wide belt annulus. The high e invokes a dynamical history where Fom b may have experienced a significant dynamical interaction with a hypothetical planet Fom c, and the current orbital configuration may be relatively short-lived. Any weakly bound satellite system surrounding a planet would be sheared and dynamically heated at periapse. Argue that Fom b's minimum mass is that of a dwarf planet in order for a circumplanetary satellite system to remain bound to a sufficient radius from the planet to be consistent with the dust scattered light hypothesis. Fom b may be optically bright because the recent passage through periapse and/or the ascending node has increased the erosion rates of planetary satellites. In the coplanar case, Fom b will collite with the main belt around 2032, and the subsequent emergent phenomena may help determine its physical nature.
1305.2267
Bimodality of galaxy disk central surface brightness distribution in the Spitzer 3.6 micron band
Source, Courtois, Sheth, Tully
Disk central surface brightnesses (mu0) at 3.6 um for 438 galaxies (distance and absolute magnitude cutoffs) from a MIR survey S4G (Spitzer Survey of Stellar Structure in Galaxies). Demonstrate that there is a bimodality in the distribution of mu0. Investigate caveats (small number statistics, knowledge of the environmental influences, biases from low S/N or corrections for galaxy inclination). Analyses show that the bimodal distribution of mu0 cannot be due to any of these. Two modes: DM dominated mode where the DM dominates at all radii (low SB galaxies) and baryonic matter dominated mode (baryons dominate the DM in the central parts), giving rides to high SB disks. Lack of intermediate SB suggests that galaxies avoid a mode where DM and baryons are co-dominant in the central parts of galaxies.
1305.2297
Dependence of low redshift Type Ia supernovae luminosities on host galaxies
Liang, Wang
SNIa in high L hosts are brighter after light-curve correction, at 3 sigma CL. Also find: SNIa in large galaxies are brighter after correction at 2 sig. Demonstrate that the residual linearly depends on host L at a confidence of 4 sig or host size at 3.3sig CL.
Source, Courtois, Sheth, Tully
Disk central surface brightnesses (mu0) at 3.6 um for 438 galaxies (distance and absolute magnitude cutoffs) from a MIR survey S4G (Spitzer Survey of Stellar Structure in Galaxies). Demonstrate that there is a bimodality in the distribution of mu0. Investigate caveats (small number statistics, knowledge of the environmental influences, biases from low S/N or corrections for galaxy inclination). Analyses show that the bimodal distribution of mu0 cannot be due to any of these. Two modes: DM dominated mode where the DM dominates at all radii (low SB galaxies) and baryonic matter dominated mode (baryons dominate the DM in the central parts), giving rides to high SB disks. Lack of intermediate SB suggests that galaxies avoid a mode where DM and baryons are co-dominant in the central parts of galaxies.
1305.2297
Dependence of low redshift Type Ia supernovae luminosities on host galaxies
Liang, Wang
SNIa in high L hosts are brighter after light-curve correction, at 3 sigma CL. Also find: SNIa in large galaxies are brighter after correction at 2 sig. Demonstrate that the residual linearly depends on host L at a confidence of 4 sig or host size at 3.3sig CL.
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