Search Publications
The Local Stellar Halo is Not Dominated by a Single Radial Merger Event
Kim, Bokyoung; Lépine, Sebastien; Newberg, Heidi Jo +1 more
We use halo dwarf stars with photometrically determined metallicities that are located within 2 kpc of the Sun to identify local halo substructure. The kinematic properties of these stars do not indicate a single, dominant radial merger event (RME). The retrograde Virgo Radial Merger (VRM) component has [Fe/H] = -1.7. A second, nonrotating RME com…
RESOLVE and ECO: Finding Low-metallicity z 0 Dwarf AGN Candidates Using Optimized Emission-line Diagnostics
Moffett, Amanda J.; Kannappan, Sheila J.; Norris, Mark A. +6 more
Existing star-forming vs. active galactic nucleus (AGN) classification schemes using optical emission-line diagnostics mostly fail for low-metallicity and/or highly star-forming galaxies, missing AGN in typical z ~ 0 dwarfs. To recover AGN in dwarfs with strong emission lines (SELs), we present a classification scheme optimizing the use of existin…
Interferometric Detections of sdO Companions Orbiting Three Classical Be Stars
Gies, Douglas R.; Wang, Luqian; Klement, Robert +17 more
Classical Be stars are possible products of close binary evolution, in which the mass donor becomes a hot, stripped O- or B-type subdwarf (sdO/sdB), and the mass gainer spins up and grows a disk to become a Be star. While several Be+sdO binaries have been identified, dynamical masses and other fundamental parameters are available only for a single…
Substructure at High Speed. II. The Local Escape Velocity and Milky Way Mass with Gaia eDR3
Necib, Lina; Lin, Tongyan
Measuring the escape velocity of the Milky Way is critical in obtaining the mass of the Milky Way, understanding the dark matter velocity distribution, and building the dark matter density profile. In Necib & Lin, we introduced a strategy to robustly measure the escape velocity. Our approach takes into account the presence of kinematic substru…
Survey of Ices toward Massive Young Stellar Objects. I. OCS, CO, OCN-, and CH3OH
Boogert, A. C. A.; Brewer, K.; Brittain, A. +1 more
An important tracer of the origin and evolution of cometary ices is the comparison with ices found in dense clouds and toward young stellar objects (YSOs). We present a survey of ices in the 2-5 µm spectra of 23 massive YSOs, taken with the NASA InfraRed Telescope Facility SpeX spectrometer. The 4.90 µm absorption band of OCS ice is de…
Dissecting Nearby Galaxies with piXedfit. I. Spatially Resolved Properties of Stars, Dust, and Gas as Revealed by Panchromatic SED Fitting
Tacchella, Sandro; Wu, Po-Feng; Morishita, Takahiro +5 more
We study spatially resolved properties (on spatial scales of ~1-2 kpc out to at least 3 effective radii) of the stars, dust, and gas in 10 nearby spiral galaxies. The properties of the stellar population and dust are derived by fitting the spatially resolved spectral energy distribution (SED) with more than 20 photometric bands ranging from far-ul…
Effects of Grain Alignment with Magnetic Fields on Grain Growth and the Structure of Dust Aggregates
Hoang, Thiem
Dust grains drift through the interstellar medium and are aligned with the magnetic field. Here we study the effect of grain alignment and motion on grain growth in molecular clouds (MCs). We first discuss the characteristic timescales of alignment of the grain axis of maximum inertia ( $\hat{{\boldsymbol{a}}}$ 1) with its angular momen…
CLEAR: Paschen-β Star Formation Rates and Dust Attenuation of Low-redshift Galaxies
Papovich, Casey; Finkelstein, Steven L.; Cleri, Nikko J. +12 more
We use Paschen-β (Paβ; 1282 nm) observations from the Hubble Space Telescope G141 grism to study the star formation and dust-attenuation properties of a sample of 29 low-redshift (z < 0.287) galaxies in the CANDELS Lyα Emission at Reionization survey. We first compare the nebular attenuation from Paβ/Hα with the stellar attenuation inferred fro…
Classifying Unidentified X-Ray Sources in the Chandra Source Catalog Using a Multiwavelength Machine-learning Approach
Kargaltsev, Oleg; Chen, Steven; Yang, Hui +3 more
The rapid increase in serendipitous X-ray source detections requires the development of novel approaches to efficiently explore the nature of X-ray sources. If even a fraction of these sources could be reliably classified, it would enable population studies for various astrophysical source types on a much larger scale than currently possible. Clas…
Homologous Accelerated Electron Beams, a Quasiperiodic Fast-propagating Wave, and a Coronal Mass Ejection Observed in One Fan-spine Jet
Shen, Yuandeng; Zhou, Chengrui; Zhou, Xinping +3 more
Using imaging and radio multi-wavelength observations, we studied the origin of two homologous accelerated electron beams and a quasiperiodic fast-propagating (QFP) wave train associated with a solar jet on 2012 July 14. The jet occurred in a small-scale fan-spine magnetic system embedded in a large-scale pseudostreamer associated with a GOES C1.4…