Search Publications
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…
The Second Earth Trojan 2020 XL5
Tholen, David J.; Hui, Man-To; Wiegert, Paul A. +1 more
The Earth Trojans are coorbitals librating around the Lagrange points L 4 or L 5 of the Sun-Earth system. Although many numerical studies suggest that they can maintain their dynamical status and be stable on timescales up to a few tens of thousands of years or even longer, they remain an elusive population. Thus far only one…
The Decline and Fall of the Youngest Planetary Nebula
Balick, Bruce; Guerrero, Martín A.; Ramos-Larios, Gerardo
The Stingray Nebula, a.k.a. Hen3-1357, appeared for the first time in 1990 when bright nebular lines and radio emission that had not been observed before were unexpectedly discovered. In the ensuing years, the nebula faded precipitously. We report changes in shape and large decreases in its nebular emission-line fluxes based on well-calibrated ima…
Machine Learning the Sixth Dimension: Stellar Radial Velocities from 5D Phase-space Correlations
Lisanti, Mariangela; Cohen, Timothy; Dropulic, Adriana +3 more
The Gaia satellite will observe the positions and velocities of over a billion Milky Way stars. In the early data releases, the majority of observed stars do not have complete 6D phase-space information. In this Letter, we demonstrate the ability to infer the missing line-of-sight velocities until more spectroscopic observations become available. …
Hubble Space Telescope Observations of the Old Pulsar PSR J0108-1431
Pavlov, George G.; Mignani, Roberto P.; Abramkin, Vadim +1 more
We present results of optical-UV observations of the 200 Myr old rotation-powered radio pulsar J0108-1431 with the Hubble Space Telescope. We found a putative candidate for the far-UV (FUV) pulsar counterpart, with the flux density fν = 9.0 ± 3.2 nJy at λ = 1528 Å. The pulsar was not detected, however, at longer wavelengths, with 3σ upp…