Search Publications
Outlier Detection in the DESI Bright Galaxy Survey
Melchior, Peter; Ward, Charlotte; Goulding, Andy +3 more
We present an unsupervised search for outliers in the Bright Galaxy Survey (BGS) data set from the DESI Early Data Release. This analysis utilizes an autoencoder to compress galaxy spectra into a compact, redshift-invariant latent space, and a normalizing flow to identify low-probability objects. The most prominent outliers show distinctive spectr…
Shocks and Photoionization of the Inner 650 au Jet of the Interacting Binary Star R Aquarii from Multiwavelength Hubble Space Telescope Observations
Montez, Rodolfo; Raymond, John C.; Karovska, Margarita +3 more
Astrophysical jets are present in a range of environments, including young stellar objects, X-ray binaries, and active galactic nuclei, but their formation is still not fully understood. As one of the nearest symbiotic binary stars, R Aquarii (D ~ 220 pc) offers a unique opportunity to study the inner region within ~600 au of the jet source, which…
A Dwarf Galaxy Debris Stream Associated with Palomar 1 and the Anticenter Stream
Tan, Ke-Feng; Zhao, Gang; Zhao, Jing-Kun +2 more
We report the discovery of a new stream (dubbed as Yangtze) detected in Gaia Data Release 3. The stream is at a heliocentric distance of ~9.12 kpc and spans nearly 27° by 1.°9 on the sky. The color-magnitude diagram of Yangtze indicates a stellar population of age ~11 Gyr and [M/H] ~ -0.7 dex. It has a number density of about 5.5 stars deg-2<…
Far-ultraviolet Dust Extinction and Molecular Hydrogen in the Diffuse Milky Way Interstellar Medium
Gordon, Karl D.; Van De Putte, Dries; Cartledge, Stefan I. B. +2 more
We aim to compare variations in the full-UV dust extinction curve (912-3000 Å), with the H I/H2/total H content along diffuse Milky Way sightlines, to investigate possible connections between ISM conditions and dust properties. We combine an existing sample of 75 UV extinction curves based on IUE and FUSE data, with atomic and molecular…
GTC Follow-up Observations of Very Metal-poor Star Candidates from DESI
Cunha, Katia; Smith, Verne V.; Moustakas, John +48 more
The observations from the Dark Energy Spectroscopic Instrument (DESI) will significantly increase the numbers of known extremely metal-poor stars by a factor of ~10, improving the sample statistics to study the early chemical evolution of the Milky Way and the nature of the first stars. In this paper we report follow-up observations with high sign…
HALO7D. III. Chemical Abundances of Milky Way Halo Stars from Medium-resolution Spectra
Guhathakurta, Puragra; Kirby, Evan N.; Cunningham, Emily C. +4 more
The Halo Assembly in Lambda Cold Dark Matter: Observations in 7 Dimensions (HALO7D) survey measures the kinematics and chemical properties of stars in the Milky Way (MW) stellar halo to learn about the formation of our Galaxy. HALO7D consists of Keck II/DEIMOS spectroscopy and Hubble Space Telescope-measured proper motions of MW halo main-sequence…
GRB 080503: A Very Early Blue Kilonova and an Adjacent Nonthermal Radiation Component
Zhou, Hao; Jin, Zhi-Ping; Covino, Stefano +5 more
The temporal behavior of the very dim optical afterglow of GRB 080503 is at odds with the regular forward shock afterglow model and a sole kilonova component responsible for optical emission has been speculated in some literature. Here we analyze the optical afterglow data available in archive and construct time-resolved spectra. The significant d…
A Spectroscopic Analysis of a Sample of K2 Planet-host Stars: Stellar Parameters, Metallicities and Planetary Radii
Cunha, Katia; Smith, Verne V.; Howell, Steve B. +5 more
The physical properties of transiting exoplanets are connected with the physical properties of their host stars. We present a homogeneous spectroscopic analysis based on the spectra of FGK-type stars observed with the Hydra spectrograph on the WIYN telescope. We derived the effective temperatures, surface gravities, and metallicities, for 81 stars…
Examining Neutrino-Matter Interactions in the Cassiopeia A Supernova
Sato, Toshiki; Hughes, John P.; Yoshida, Takashi +4 more
Neutrino interactions with stellar material are widely believed to be fundamental to the explosion of massive stars. However, this important process has remained difficult to confirm observationally. We propose a new method to verify it using X-ray observations of the supernova remnant Cassiopeia A. The elemental composition in its Fe-rich ejecta …
X-Ray and Near-Infrared Observations of the Middle-aged Pulsar B1055-52, Its Multiwavelength Spectrum, and Proper Motion
Pavlov, G. G.; Kargaltsev, O.; Hare, J. +1 more
Previous observations of the middle-aged γ-ray, X-ray, and radio pulsar B1055-52 indicated some peculiarities, such as a suspected changing of the X-ray flux and spectral parameters, a large excess of the alleged thermal component of the UV spectrum over the Rayleigh-Jeans extension of the X-ray thermal spectrum, and a possible double break in the…