Search Publications
High-resolution Spectroscopy of Extremely Metal-poor Stars from SDSS/SEGUE. III. Unevolved Stars with [Fe/H] ≲ -3.5
Honda, Satoshi; Beers, Timothy C.; Lee, Young Sun +2 more
We present elemental abundances for eight unevolved extremely metal-poor (EMP) stars with {T}{eff}> 5500 {{K}}, among which seven have [{Fe}/{{H}}]< -3.5. The sample is selected from the Sloan Digital Sky Survey/Sloan Extension for Galactic Understanding and Exploration (SDSS/SEGUE) and our previous high-resolution spectroscopic f…
Strong H I Lyman-α variations from an 11 Gyr-old host star: a planetary origin?
Thomas, N.; Ehrenreich, D.; Lovis, C. +8 more
Kepler-444 provides a unique opportunity to probe the atmospheric composition and evolution of a compact system of exoplanets smaller than the Earth. Five planets transit this bright K star at close orbital distances, but they are too small for their putative lower atmosphere to be probed at optical/infrared wavelengths. We used the Space Telescop…
The Origin of the Iron-rich Knot in Tycho’s Supernova Remnant
Petre, Robert; Yamaguchi, Hiroya; Hughes, John P. +5 more
X-ray observations of supernova remnants (SNRs) allow us to investigate the chemical inhomogeneity of ejecta, offering unique insight into the nucleosynthesis in supernova explosions. Here we present detailed imaging and spectroscopic studies of the “Fe knot” located along the eastern rim of the Type Ia SNR Tycho (SN 1572) using Suzaku and Chandra…
The Impact of the Group Environment on the O VI Circumgalactic Medium
Charlton, Jane C.; Kacprzak, Glenn G.; Churchill, Christopher W. +3 more
We present a study comparing O VI λλ1031, 1037 doublet absorption found toward group galaxy environments to that of isolated galaxies. The O VI absorption in the circumgalactic medium (CGM) of isolated galaxies has been studied previously by the “Multiphase Galaxy Halos” survey, where the kinematics and absorption properties of the CGM have been i…
Doppler Shift Oscillations from a Hot Line Observed by IRIS
Huang, Y.; Li, D.; Zhang, Q. M. +4 more
We present a detailed investigation of the Doppler shift oscillations in a hot loop during an M7.1 flare on 2014 October 27 observed by the Interface Region Imaging Spectrograph. The periodic oscillations are observed in the Doppler shift of Fe xxi 1354.09 Å (log T∼ 7.05), and the dominant period is about 3.1 minutes. However, such 3.1 minute osci…
Strongly Misaligned Triple System in SR 24 Revealed by ALMA
Fernández-López, M.; Zapata, L. A.; Gabbasov, R.
We report the detection of the 1.3 mm continuum and the molecular emission of the disks of the young triple system SR24 by analyzing ALMA (The Atacama Large Millimeter/Submillimter Array) subarcsecond archival observations. We estimate the mass of the disks (0.025 M ⊙ and 4 × 10-5 M ⊕ for SR24S and SR24N, respectiv…
Luminosities and infrared excess in Type II and anomalous Cepheids in the Large and Small Magellanic Clouds
Groenewegen, M. A. T.; Jurkovic, M. I.
Type II and anomalous Cepheids (ACs) are useful distance indicators when there are too few classical Cepheids or when RR Lyrae stars are too faint. Type II and ACs follow a period-luminosity relation as well, but they are less well-studied classes of objects. In this paper we study the sample of 335 Type II and ACs in the Small and Large Magellani…
A swirling jet in the quasar 1308+326
Britzen, S.; Krause, M.; Moser, L. +12 more
Context. Despite numerous and detailed studies of the jets of active galactic nuclei (AGN) on pc-scales, many questions are still debated. The physical nature of the jet components is one of the most prominent unsolved problems, as is the launching mechanism of jets in AGN. The quasar 1308+326 (z = 0.997) allows us to study the overall properties …
Noncircular features in Saturn's rings IV: Absolute radius scale and Saturn's pole direction
Nicholson, Philip D.; French, Richard G.; McGhee-French, Colleen A. +6 more
We present a comprehensive solution for the geometry of Saturn's ring system, based on orbital fits to an extensive set of occultation observations of 122 individual ring edges and gaps. We begin with a restricted set of very high quality Cassini VIMS, UVIS, and RSS measurements for quasi-circular features in the C and B rings and the Cassini Divi…
VLA Measurements of Faraday Rotation through Coronal Mass Ejections
Kooi, Jason E.; Fischer, Patrick D.; Buffo, Jacob J. +1 more
Coronal mass ejections (CMEs) are large-scale eruptions of plasma from the Sun, which play an important role in space weather. Faraday rotation is the rotation of the plane of polarization that results when a linearly polarized signal passes through a magnetized plasma such as a CME. Faraday rotation is proportional to the path integral through th…