Search Publications
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…
Detection of Multiple Phase Space Overdensities of GSE Stars by Orbit Integration
Zhao, Gang; Chen, Yuqin; Li, Chengdong +5 more
In N-body simulations, nearly radial mergers can form shell-like overdensities in the sky position and phase space (r - v r ) due to the combination of dynamical friction and tidal stripping. The merger event of Gaia-Sausage-Enceladus (GSE) has provided a unique opportunity to study the shells in the phase space. To search for them, we…
The Isaac Newton Telescope Monitoring Survey of Local Group Dwarf Galaxies. V. The Star Formation History of Sagittarius Dwarf Irregular Galaxy Derived from Long-period Variable Stars
Javadi, Atefeh; Saremi, Elham; van Loon, Jacco Th. +7 more
We conducted an optical monitoring survey of the Sagittarius dwarf irregular galaxy (SagDIG) during the period of 2016 June-2017 October, using the 2.5 m Isaac Newton Telescopeat La Palama. Our goal was to identify long-period variable stars (LPVs), namely, asymptotic giant branch stars (AGBs) and red supergiant stars, to obtain the star formation…
Steadiness of Coronal Heating
Judge, P. G.
The EUI instrument on the Solar Orbiter spacecraft has obtained the most stable, high-resolution images of the solar corona from its orbit with a perihelion near 0.4 au. A sequence of 360 images obtained at 17.1 nm, between 2022 October 25 19:00 and 19:30 UT, is scrutinized. One image pixel corresponds to 148 km at the solar surface. The widely he…