Search Publications
The Overlooked Role of Stellar Variability in the Extended Main Sequence of LMC Intermediate-age Clusters
Contreras Ramos, R.; Vivas, A. K.; Strader, J. +2 more
Intermediate-age star clusters in the Large Magellanic Cloud show extended main sequence turnoffs (MSTOs) that are not consistent with a canonical single stellar population. These broad turnoffs have been interpreted as evidence for extended star formation and/or stellar rotation. Since most of these studies use single frames per filter to do the …
A Comprehensive Archival Chandra Search for X-Ray Emission from Ultracompact Dwarf Galaxies
Greene, Jenny E.; Mulchaey, John; Pandya, Viraj
We present the first comprehensive archival study of the X-ray properties of ultracompact dwarf (UCD) galaxies, with the goal of identifying weakly accreting central black holes in UCDs. Our study spans 578 UCDs distributed across 13 different host systems, including clusters, groups, fossil groups, and isolated galaxies. Of the 336 spectroscopica…
Radar scattering of linear dunes and mega-yardangs: Application to Titan
Radebaugh, Jani; Paillou, Philippe; Wall, Stephen +1 more
The Ku-band (13.8 GHz - 2.2 cm) RADAR instrument onboard the Cassini-Huygens spacecraft has revealed the richness of the surface of Titan, as numerous seas, lakes, rivers, cryo-volcanic flows and vast dune fields have been discovered. Linear dunes are a major geomorphological feature present on Titan, covering up to 17% of its surface, mainly in e…
IVS Observation of ICRF2-Gaia Transfer Sources
Charlot, P.; Bourda, G.; Le Bail, K. +11 more
The second realization of the International Celestial Reference Frame (ICRF2), which is the current fundamental celestial reference frame adopted by the International Astronomical Union, is based on Very Long Baseline Interferometry (VLBI) data at radio frequencies in X band and S band. The European Space Agency’s Gaia mission, launched on 2013 De…
Relationship between supergranulation flows, magnetic cancellation and network flares
Solanki, S. K.; Glassmeier, K. H.; Innes, D. E. +1 more
Context. Photospheric flows create a network of often mixed-polarity magnetic field in the quiet Sun, where small-scale eruptions and network flares are commonly seen.
Aims: The aim of this paper is (1) to describe the characteristics of the flows that lead to these energy releases, (2) to quantify the energy build up due to photospheric flow…
ALMA probes the molecular gas reservoirs in the changing-look Seyfert galaxy Mrk 590
Vestergaard, M.; Peterson, B. M.; Koay, J. Y. +2 more
We investigate if the active galactic nucleus (AGN) of Mrk 590, whose supermassive black hole was until recently highly accreting, is turning off due to a lack of central gas to fuel it. We analyse new subarcsecond resolution Atacama Large Millimetre/submilllimetre Array maps of the 12CO(3-2) line and 344 GHz continuum emission in Mrk 5…
Very Low-mass Stellar and Substellar Companions to Solar-like Stars from MARVELS. VI. A Giant Planet and a Brown Dwarf Candidate in a Close Binary System HD 87646
Bizyaev, Dmitry; Ge, Jian; Schneider, Donald P. +34 more
We report the detections of a giant planet (MARVELS-7b) and a brown dwarf (BD) candidate (MARVELS-7c) around the primary star in the close binary system, HD 87646. To the best of our knowledge, it is the first close binary system with more than one substellar circumprimary companion that has been discovered. The detection of this giant planet was …
Gamma-ray burst polarization reduction induced by the Lorentz invariance violation
Chang, Zhe; Li, Xin; Lin, Hai-Nan
It has been observed that photons in the prompt emission of some gamma-ray bursts (GRBs) are highly polarized. The high polarization is used by some authors to give a strict constraint on the Lorentz invariance violation (LIV). If the Lorentz invariance is broken, the polarization vector of a photon may rotate during its propagation. The rotation …
Limb-darkening coefficients from line-blanketed non-LTE hot-star model atmospheres
Howarth, I. D.; Reeve, D. C.
We present grids of limb-darkening coefficients computed from non-local thermodynamic equilibrium (non-LTE), line-blanketed TLUSTY model atmospheres, covering effective-temperature and surface-gravity ranges of 15-55 kK and 4.75 dex (cgs) down to the effective Eddington limit, at 2×, 1×, 0.5× (Large Magellanic Cloud), 0.2× (Small Magellanic Cloud)…
Scientific considerations for future spectroscopic measurements from space of activity on the Sun
Holman, Gordon D.
High-resolution UV and X-ray spectroscopy are important to understanding the origin and evolution of magnetic energy release in the solar atmosphere, as well as the subsequent evolution of heated plasma and accelerated particles. Electromagnetic radiation is observed from plasma heated to temperatures ranging from about 10 kK to above 10 MK, from …