Search Publications
A VLBA Survey of Radio Stars in the Orion Nebula Cluster. II. Astrometry
Menten, Karl M.; Forbrich, Jan; Reid, Mark J. +1 more
From Very Long Baseline Array (VLBA) observations we previously identified a population of 123 young stellar systems with nonthermal radio emission toward the core of the Orion Nebula Cluster (ONC). We find optical sources in the Gaia DR2 catalog for 34 of them within 0"2 of the radio positions. Most of the radio sources are likely companions of G…
The GALAH Survey: No Chemical Evidence of an Extragalactic Origin for the Nyx Stream
Lewis, Geraint F.; Ting, Yuan-Sen; Casey, Andrew R. +20 more
The results from the ESA Gaia astrometric mission and deep photometric surveys have revolutionized our knowledge of the Milky Way. There are many ongoing efforts to search these data for stellar substructure to find evidence of individual accretion events that built up the Milky Way and its halo. One of these newly identified features, called Nyx,…
Discovery, TESS Characterization, and Modeling of Pulsations in the Extremely Low-mass White Dwarf GD 278
Córsico, Alejandro H.; Hermes, J. J.; Bell, Keaton J. +5 more
We report the discovery of pulsations in the extremely low-mass (ELM), likely helium-core white dwarf GD 278 via ground- and space-based photometry. GD 278 was observed by the Transiting Exoplanet Survey Satellite (TESS) in Sector 18 at a 2 minute cadence for roughly 24 days. The TESS data reveal at least 19 significant periodicities between 2447 …
The Common Origin of High-energy Protons in Solar Energetic Particle Events and Sustained Gamma-Ray Emission from the Sun
Gopalswamy, N.; Yashiro, S.; Mäkelä, P. +2 more
We report that the number of >500 MeV protons (Ng) inferred from sustained gamma-ray emission (SGRE) from the Sun is significantly correlated with that of protons propagating into space (NSEP) as solar energetic particles (SEPs). Under the shock paradigm for SGRE, shocks driven by coronal mass ejections (CMEs) accelerate h…
HAWC Search for High-mass Microquasars
Lee, W. H.; Alvarez, C.; Hernandez, S. +86 more
Microquasars with high-mass companion stars are promising very high energy (VHE; 0.1-100 TeV) gamma-ray emitters, but their behaviors above 10 TeV are poorly known. Using the High Altitude Water Cerenkov (HAWC) observatory, we search for excess gamma-ray emission coincident with the positions of known high-mass microquasars (HMMQs). No significant…
Formation of Multiple Populations of M5 (NGC 5904)
Lee, Jae-Woo
With our new Ca-CN-CH-NH photometry, we revisit the globular cluster (GC) M5. We find that M5 is a mono-metallic GC with a small metallicity dispersion. Our carbon abundances show that the σ[C/Fe] of the M5 CN-s population, with depleted carbon and enhanced nitrogen abundances, is significantly large for a single stellar population. Our new analys…
Tracing the Origin of Moving Groups. III. Detecting Moving Groups in LAMOST DR7
Zhao, Gang; Yang, Yong; Zhao, Jingkun +2 more
We revisit the moving groups (MGs) in the solar neighborhood with a sample of 91,969 nearby stars constructed from LAMOST DR7. Using the wavelet technique and Monte Carlo simulations, five MGs together with a new candidate located at V≃-130 km s-1 are detected simultaneously in $V-\sqrt{{U}^{2}+2{V}^{2}}$ space. Taking into account the …
Gaussian Process Reconstruction of Reionization History
Hazra, Dhiraj Kumar; Krishak, Aditi
We reconstruct the history of reionization using Gaussian process regression. Using the UV luminosity data compilation from Hubble Frontiers Fields we reconstruct the redshift evolution of UV luminosity density and thereby the evolution of the source term in the ionization equation. This model-independent reconstruction rules out single power-law …
SiO Outflows as Tracers of Massive Star Formation in Infrared Dark Clouds
Caselli, Paola; Kong, Shuo; Tan, Jonathan C. +4 more
To study the early phases of massive star formation, we present ALMA observations of SiO(5-4) emission and VLA observations of 6 cm continuum emission toward 32 Infrared Dark Cloud clumps, spatially resolved down to ≲0.05 pc. Out of the 32 clumps, we detect SiO emission in 20 clumps, and in 11 of them the SiO emission is relatively strong and like…
SOFIA-upGREAT Imaging Spectroscopy of the [C II] 158 µm Fine-structure Line of the Sgr B Region in the Galactic Center
Harris, A. I.; Morris, M. R.; Stutzki, J. +8 more
We report SOFIA-upGREAT spectroscopic imaging of the [C II] 158 µm spectral line, as well as a number of [O I] 63 µm spectra, across a 67 × 45 pc field toward the Sgr B region in our Galactic center. The fully sampled and velocity-resolved [C II] images have 0.55 pc spatial and 1 km s-1 velocity resolutions. We find that Sgr…