Jessica Mink

The 2MASS Redshift Survey?Description and Data Release

We present the results of the 2MASS Redshift Survey (2MRS), a ten-year project to map the full three-dimensional distribution of galaxies in the nearby universe. The Two Micron All Sky Survey (2MASS) was completed in 2003 and its final data products, including an extended source catalog (XSC), are available online. The 2MASS XSC contains nearly a million galaxies with K_s ≤ 13.5 mag and is essentially complete and mostly unaffected by interstellar extinction and stellar confusion down to a galactic latitude of |b| = 5° for bright galaxies. Near-infrared wavelengths are sensitive to the old stellar populations that dominate galaxy masses, making 2MASS an excellent starting point to study the distribution of matter in the nearby universe. We selected a sample of 44,599 2MASS galaxies with K_s ≤ 11.75 mag and |b| ≥ 5° (≥8° toward the Galactic bulge) as the input catalog for our survey. We obtained spectroscopic observations for 11,000 galaxies and used previously obtained velocities for the remainder of the sample to generate a redshift catalog that is 97.6% complete to well-defined limits and covers 91% of the sky. This provides an unprecedented census of galaxy (baryonic mass) concentrations within 300 Mpc. Earlier versions of our survey have been used in a number of publications that have studied the bulk motion of the Local Group, mapped the density and peculiar velocity fields out to 50 h^(–1) Mpc, detected galaxy groups, and estimated the values of several cosmological parameters. Additionally, we present morphological types for a nearly complete sub-sample of 20,860 galaxies with K_s ≤ 11.25 mag and |b| ≥ 10°.

THE Hα EMISSION OF NEARBY M DWARFS AND ITS RELATION TO STELLAR ROTATION

National Science Foundation (U.S.). Astronomy and Astrophysics Postdoctoral Fellowship (Award AST-1602597)

CfAIR2: NEAR-INFRARED LIGHT CURVES OF 94 TYPE Ia SUPERNOVAE

CfAIR2 is a large homogeneously reduced set of near-infrared (NIR) light curves for Type Ia supernovae (SN Ia) obtained with the 1.3m Peters Automated InfraRed Imaging TELescope (PAIRITEL). This data set includes 4607 measurements of 94 SN Ia and 4 additional SN Iax observed from 2005-2011 at the Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona. CfAIR2 includes JHKs photometric measurements for 88 normal and 6 spectroscopically peculiar SN Ia in the nearby universe, with a median redshift of z~0.021 for the normal SN Ia. CfAIR2 data span the range from -13 days to +127 days from B-band maximum. More than half of the light curves begin before the time of maximum and the coverage typically contains ~13-18 epochs of observation, depending on the filter. We present extensive tests that verify the fidelity of the CfAIR2 data pipeline, including comparison to the excellent data of the Carnegie Supernova Project. CfAIR2 contributes to a firm local anchor for supernova cosmology studies in the NIR. Because SN Ia are more nearly standard candles in the NIR and are less vulnerable to the vexing problems of extinction by dust, CfAIR2 will help the supernova cosmology community develop more precise and accurate extragalactic distance probes to improve our knowledge of cosmological parameters, including dark energy and its potential time variation.

MWC 349A and B Are Not Gravitationally Bound: New Evidence

The age and evolutionary status of MWC 349A, the unique emission-line star with maser and laser radiation in hydrogen recombination lines, remain unknown, because the spectrum of the star is veiled by bright emission from the ionized disk and wind. The major argument for this massive (>10 M ⊙) star being evolved is its association with a close-by (2.4 arcsec) companion, MWC 349B, whose B0III spectrum implies an age of a few million years. However, newly obtained high-resolution spectra of MWC 349B reveal a difference of ≈35 km s−1 in the radial velocities of the two stars, which makes their being gravitationally bound highly improbable. An estimate of the relative proper motion of the two stars seems to confirm this conclusion. This reopens the previously suggested possibility that MWC 349A is a young massive star in a region of active star formation close to Cyg OB2 association. MWC 349B, which moves with a speed ≥35 km s−1 relative to Cyg OB2, may be a runaway star from this association.