Search Publications
ALFALFA Discovery of the Most Metal-poor Gas-rich Galaxy Known: AGC 198691
McQuinn, Kristen B. W.; Cannon, John M.; Skillman, Evan D. +12 more
We present spectroscopic observations of the nearby dwarf galaxy AGC 198691. This object is part of the Survey of H I in Extremely Low-Mass Dwarfs project, which is a multi-wavelength study of galaxies with H I masses in the range of 106-107.2 M ⊙, discovered by the Arecibo Legacy Fast ALFA (ALFALFA) survey. We hav…
Star-forming Brightest Cluster Galaxies at 0.25 < z < 1.25: A Transitioning Fuel Supply
Schrabback, T.; Zenteno, A.; Desai, S. +23 more
We present a multiwavelength study of the 90 brightest cluster galaxies (BCGs) in a sample of galaxy clusters selected via the Sunyaev Zel’dovich effect by the South Pole Telescope, utilizing data from various ground- and space-based facilities. We infer the star-formation rate (SFR) for the BCG in each cluster—based on the UV and IR continuum lum…
Multiple Populations in the Old and Massive Small Magellanic Cloud Globular Cluster NGC 121
Dalessandro, E.; Mucciarelli, A.; Origlia, L. +3 more
We used a combination of optical and near-UV Hubble Space Telescope photometry and FLAMES/ESO-VLT high-resolution spectroscopy to characterize the stellar content of the old and massive globular cluster (GC) NGC 121 in the Small Magellanic Cloud (SMC). We report on the detection of multiple stellar populations, the first case in the SMC stellar cl…
Discovery of Rotational Modulations in the Planetary-mass Companion 2M1207b: Intermediate Rotation Period and Heterogeneous Clouds in a Low Gravity Atmosphere
Showman, Adam P.; Apai, Dániel; Marley, Mark S. +2 more
Rotational modulations of brown dwarfs have recently provided powerful constraints on the properties of ultra-cool atmospheres, including longitudinal and vertical cloud structures and cloud evolution. Furthermore, periodic light curves directly probe the rotational periods of ultra-cool objects. We present here, for the first time, time-resolved …
IC 751: A New Changing Look AGN Discovered by NuSTAR
Harrison, F. A.; Boggs, S.; Stern, D. +12 more
We present results of five Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the type 2 active galactic nucleus (AGN) in IC 751, three of which were performed simultaneously with XMM-Newton or Swift/X-Ray Telescope. We find that the nuclear X-ray source underwent a clear transition from a Compton-thick ({N}{{H}}≃ 2× {10}
Non-LTE Inversions of the Mg II h & k and UV Triplet Lines
Leenaarts, Jorrit; Asensio Ramos, Andrés; de la Cruz Rodríguez, Jaime
The Mg II h & k lines are powerful diagnostics for studying the solar chromosphere. They have become particularly popular with the launch of the Interface Region Imaging Spectrograph (IRIS) satellite, and a number of studies that include these lines have lead to great progress in understanding chromospheric heating, in many cases thanks to the…
Photolytic Hazes in the Atmosphere of 51 Eri b
Morley, C. V.; Zahnle, K.; Moses, J. I. +1 more
We use a 1D model to address photochemistry and possible haze formation in the irradiated warm Jupiter, 51 Eridani b. The intended focus was to be carbon, but sulfur photochemistry turns out to be important. The case for organic photochemical hazes is intriguing but falls short of being compelling. If organic hazes form, they are likeliest to do s…
Data-driven Radiative Hydrodynamic Modeling of the 2014 March 29 X1.0 Solar Flare
Liu, Wei; Allred, Joel C.; Kleint, Lucia +2 more
Spectroscopic observations of solar flares provide critical diagnostics of the physical conditions in the flaring atmosphere. Some key features in observed spectra have not yet been accounted for in existing flare models. Here we report a data-driven simulation of the well-observed X1.0 flare on 2014 March 29 that can reconcile some well-known spe…
SN Refsdal: Photometry and Time Delay Measurements of the First Einstein Cross Supernova
Sharon, K.; Molino, A.; Zitrin, A. +16 more
We present the first year of Hubble Space Telescope imaging of the unique supernova (SN) “Refsdal,” a gravitationally lensed SN at z = 1.488 ± 0.001 with multiple images behind the galaxy cluster MACS J1149.6+2223. The first four observed images of SN Refsdal (images S1-S4) exhibited a slow rise (over ∼150 days) to reach a broad peak brightness ar…
Infrared Color Selection of Massive Galaxies at z > 3
Daddi, E.; Elbaz, D.; Shu, X. +29 more
We introduce a new color selection technique to identify high-redshift, massive galaxies that are systematically missed by Lyman-break selection. The new selection is based on the H160 (H) and Infrared Array Camera (IRAC) 4.5 µm bands, specifically H-[4.5]\gt 2.25 mag. These galaxies, called “HIEROs,” include two major populations…