Frank Varosi - NASA Goddard Space Flight Center

Frank Varosi
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Frank Varosi
NASA Goddard Space Flight Center
United States

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Astrophysics (3)
Earth and Planetary Astrophysics (2)
Solar and Stellar Astrophysics (1)

Publications Authored By Frank Varosi

Planet searches using the radial velocity technique show a paucity of companions to solar-type stars within ~5 AU in the mass range of ~10 - 80 M$_{\text{Jup}}$. This deficit, known as the brown dwarf desert, currently has no conclusive explanation. New substellar companions in this region help asses the reality of the desert and provide insight to the formation and evolution of these objects. Read More

We present a new short-period brown dwarf candidate around the star TYC 1240-00945-1. This candidate was discovered in the first year of the Multi-object APO Radial Velocity Exoplanets Large-area Survey (MARVELS), which is part of the third phase of the Sloan Digital Sky Survey (SDSS-III), and we designate the brown dwarf as MARVELS-1b. MARVELS uses the technique of dispersed fixed-delay interferometery to simultaneously obtain radial velocity measurements for 60 objects per field using a single, custom-built instrument that is fiber fed from the SDSS 2. Read More

Affiliations: 1NASA Goddard Space Flight Center, 2NASA Goddard Space Flight Center
Category: Astrophysics

A Monte Carlo model of radiative transfer in multi-phase dusty media is applied to the situation of stars and clumpy dust in a sphere or a disk. The distribution of escaping and absorbed photons are shown for various filling factors and densities. Analytical methods of approximating the escaping fraction of radiation, based on the Mega-Grains approach, are discussed. Read More

Affiliations: 1NASA Goddard Space Flight Center, 2NASA Goddard Space Flight Center
Category: Astrophysics

We present analytical approximations for calculating the scattering, absorption and escape of nonionizing photons from a spherically symmetric two-phase clumpy medium, with either a central point source of isotropic radiation, a uniform distribution of isotropic emitters, or uniformly illuminated by external sources. The analytical approximations are based on the mega-grains model of two-phase clumpy media, as proposed by Hobson & Padman, combined with escape and absorption probability formulae for homogeneous media. The accuracy of the approximations is examined by comparison with 3D Monte Carlo simulations of radiative transfer, including multiple scattering. Read More

Using the IRAS Infrared Sky Survey Atlas, we have made 60 x 60 deg mosaics of the far-infrared emission in the Milky Way. By applying a median normalizing spatial filter, we were able to eliminate the strong gradient in brightness towards the Galactic midplane. The resulting images reveal a "froth" of superposed filaments, voids, and shells. Read More