Search Publications
Metallicity Variations in the Type II Globular Cluster NGC 6934
Milone, A. P.; Marino, A. F.; Bedin, L. R. +7 more
The Hubble Space Telescope photometric survey of Galactic globular clusters (GCs) has revealed a peculiar “chromosome map” for NGC 6934. In addition to a typical sequence, similar to that observed in Type I GCs, NGC 6934 displays additional stars on the red side, analogous to the anomalous Type II GCs, as defined in our previous work. We present a…
Storm in a Teacup: X-Ray View of an Obscured Quasar and Superbubble
Mullaney, James R.; Edge, Alastair C.; Alexander, David M. +5 more
We present the X-ray properties of the “Teacup AGN” (SDSS J1430+1339), a z = 0.085 type 2 quasar that is interacting dramatically with its host galaxy. Spectral modeling of the central quasar reveals a powerful, highly obscured active galactic nucleus (AGN) with a column density of N H = (4.2-6.5) × 1023 cm-2 and a…
Toward Understanding the B[e] Phenomenon. VII. AS 386, a Single-lined Binary with a Candidate Black Hole Component
Reichart, D. E.; Miroshnichenko, A. S.; Manset, N. +24 more
We report the results of spectroscopic and photometric observations of the emission-line object AS 386. For the first time we found that it exhibits the B[e] phenomenon and fits the definition of an FS CMa type object. The optical spectrum shows the presence of a B-type star with the following properties: T eff = 11,000 ± 500 K, log L/L…
Microlensing and Intrinsic Variability of the Broad Emission Lines of Lensed Quasars
Hanslmeier, A.; Muñoz, J. A.; Falco, E. E. +5 more
We study the broad emission lines in a sample of 11 gravitationally lensed quasars with at least two epochs of observation to identify intrinsic variability and to disentangle it from microlensing. To improve our statistical significance and emphasize trends, we also include 15 lens systems with single-epoch spectra. Mg II and C III] emission line…
Mass and Light of Abell 370: A Strong and Weak Lensing Analysis
Schrabback, T.; Vulcani, B.; Hoag, A. +13 more
We present a new gravitational lens model of the Hubble Frontier Fields cluster Abell 370 (z = 0.375) using imaging and spectroscopy from Hubble Space Telescope and ground-based spectroscopy. We combine constraints from a catalog of 909 weakly lensed galaxies and 39 multiply imaged sources comprised of 114 multiple images, including a system of mu…
Studying the Ultraviolet Spectrum of the First Spectroscopically Confirmed Supernova at Redshift Two
Benoit-Lévy, A.; Bechtol, K.; Zheng, W. +89 more
We present observations of DES16C2nm, the first spectroscopically confirmed hydrogen-free superluminous supernova (SLSN-I) at redshift z≈ 2. DES16C2nm was discovered by the Dark Energy Survey (DES) Supernova Program, with follow-up photometric data from the Hubble Space Telescope, Gemini, and the European Southern Observatory Very Large Telescope …
Optical Counterparts of Ultraluminous X-Ray Sources NGC 4559 X-10 and NGC 4395 ULX-1
Vinokurov, A.; Atapin, K.; Fabrika, S.
We study the optical counterparts of ultraluminous X-ray sources (ULXs) NGC 4559 X-10 and NGC 4395 ULX-1. Their absolute magnitudes, after taking reddening into account, are M V ≈ -5.3 and M V ≈ -6.2, respectively. The spectral energy distribution (SED) of the NGC 4559 X-10 counterpart is well fitted by a spectrum of an A…
On the Impact of Helium Content on the RR Lyrae Distance Scale
Marconi, M.; Castellani, M.; Bono, G. +3 more
We constructed new sets of He-enhanced (Y = 0.30, Y = 0.40) nonlinear, time-dependent convective hydrodynamical models of RR Lyrae (RRL) stars covering a broad range in metal abundances (Z = 0.0001-0.02). The increase in He content from the canonical value (Y = 0.245) to Y = 0.30-0.40 causes a simultaneous increase in stellar luminosity and in pul…
Late-time Flattening of Type Ia Supernova Light Curves: Constraints from SN 2014J in M82
Baade, Dietrich; Sparks, William B.; Wang, Lifan +11 more
The very nearby Type Ia supernova 2014J in M82 offers a rare opportunity to study the physics of thermonuclear supernovae at extremely late phases (≳800 days). Using the Hubble Space Telescope, we obtained 6 epochs of high-precision photometry for SN 2014J from 277 days to 1181 days past the B-band maximum light. The reprocessing of electrons and …
The z = 0.54 LoBAL Quasar SDSS J085053.12+445122.5. I. Spectral Synthesis Analysis Reveals a Massive Outflow
Gallagher, Sarah C.; Terndrup, Donald M.; Leighly, Karen M. +2 more
We introduce SimBAL, a novel spectral-synthesis procedure that uses grids of ionic column densities generated by the photoionization code Cloudy and a Bayesian model calibration to forward-model broad absorption-line quasar (BALQ) spectra. We used SimBAL to analyze the Hubble Space Telescope Cosmic Origins Spectrograph (COS) spectrum of the low-re…