Search Publications
Broad Non-Gaussian Fe XXIV Line Profiles in the Impulsive Phase of the 2017 September 10 X8.3-class Flare Observed by Hinode/EIS
Reeves, Katharine K.; Polito, Vanessa; Chen, Bin +4 more
We analyze the spectra of high-temperature Fe XXIV lines observed by the Hinode/Extreme-Ultraviolet Imaging Spectrometer (EIS) during the impulsive phase of the X8.3-class flare on 2017 September 10. The line profiles are broad, show pronounced wings, and clearly depart from a single-Gaussian shape. The lines can be well fitted with κ distribution…
The Orbit of the Companion to HD 100453A: Binary-driven Spiral Arms in a Protoplanetary Disk
Dong, Ruobing; Wagner, Kevin; Apai, Dániel +9 more
HD 100453AB is a 10 ± 2 Myr old binary whose protoplanetary disk was recently revealed to host a global two-armed spiral structure. Given the relatively small projected separation of the binary (1.″05, or ∼108 au), gravitational perturbations by the binary seemed to be a likely driving force behind the formation of the spiral arms. However, the or…
Breaking the Habit: The Peculiar 2016 Eruption of the Unique Recurrent Nova M31N 2008-12a
Sabo, R.; Ness, J. -U.; Henze, M. +70 more
Since its discovery in 2008, the Andromeda galaxy nova M31N 2008-12a has been observed in eruption every single year. This unprecedented frequency indicates an extreme object, with a massive white dwarf and a high accretion rate, which is the most promising candidate for the single-degenerate progenitor of a Type Ia supernova known to date. The pr…
Phlegethon, a Nearby 75°-long Retrograde Stellar Stream
Malhan, Khyati; Ibata, Rodrigo A.; Martin, Nicolas F. +1 more
We report the discovery of a 75°-long stellar stream in the Gaia DR2 catalog, found using the new STREAMFINDER algorithm. The structure is probably the remnant of a now fully disrupted globular cluster, which lies ≈3.8 kpc away from the Sun in the direction of the Galactic bulge and possesses highly retrograde motion. We find that the system orbit…
New and Known Moving Groups and Clusters Identified in a Gaia Comoving Catalog
Faherty, Jacqueline K.; Gagné, Jonathan; Bochanski, John J. +5 more
We present a reorganization of the Oh et al. wide, comoving catalog of 4555 groups of stars (10,606 individual objects) identified in the Tycho Gaia Astrometric Survey (TGAS) into new and known coevolving groups of stars in the Milky Way. We use the BANYAN Σ kinematic analysis tool to identify 1015 individual stars in the Oh et al. catalog that yi…
Galactic Planetary Nebulae as Probes of Radial Metallicity Gradients and Other Abundance Patterns
Haywood, Misha; Stanghellini, Letizia
We use planetary nebulae (PNe) as probes to determine the Galactic radial oxygen gradients and other abundance patterns. We select data homogeneously from recent data sets, including PNe at large Galactocentric distances. The radial oxygen gradient calculated for the general PN population, which probes the region from the Galactic center out to ∼2…
Galaxies Probing Galaxies in PRIMUS. I. Sample, Spectroscopy, and Characteristics of the z\sim 0.5 Mg II-absorbing Circumgalactic Medium
Moustakas, John; Coil, Alison L.; Diamond-Stanic, Aleksandar M. +2 more
The spectroscopy of background QSO sightlines passing close to foreground galaxies is a potent technique for studying the circumgalactic medium (CGM). However, QSOs are effectively point sources, limiting their potential to constrain the size of circumgalactic gaseous structures. Here we present the first large Keck/Low-resolution Imaging Spectrom…
The Araucaria Project: High-precision Cepheid Astrophysics from the Analysis of Variables in Double-lined Eclipsing Binaries
Udalski, Andrzej; Soszyński, Igor; Thompson, Ian B. +15 more
Based on new observations and improved modeling techniques, we have reanalyzed seven Cepheids in the Large Magellanic Cloud. Improved physical parameters have been determined for the exotic system OGLE LMC-CEP-1718 composed of two first-overtone Cepheids and a completely new model was obtained for the OGLE LMC-CEP-1812 classical Cepheid. This is n…
Does Circumgalactic O VI Trace Low-pressure Gas Beyond the Accretion Shock? Clues from H I and Low-ion Absorption, Line Kinematics, and Dust Extinction
Stern, Jonathan; Faucher-Giguère, Claude-André; Hennawi, Joseph F. +3 more
Large O VI columns are observed around star-forming low-redshift ∼ {L}* galaxies, with a dependence on impact parameter indicating that most {{{O}}}5+ particles reside beyond half the halo virial radius (≳ 100 {kpc}). In order to constrain the nature of the gas traced by {{O}} {{vi}}, we analyze additional observables of the…
Predicting Stellar-mass Black Hole Populations in Globular Clusters
Rodriguez, Carl L.; Chatterjee, Sourav; Weatherford, Newlin C. +1 more
Recent discoveries of black hole (BH) candidates in Galactic and extragalactic globular clusters (GCs) have ignited interest in understanding how BHs dynamically evolve in a GC and the number of BHs ({N}BH}) that may still be retained by today’s GCs. Numerical models show that even if stellar-mass BHs are retained in today’s GCs, they a…