Search Publications
Probing the Cold Deep Depths of the California Molecular Cloud: The Icy Relationship between CO and Dust
Alves, João; Lada, Charles J.; Lombardi, Marco +3 more
We study the relationship between molecular gas and dust in the California Molecular Cloud over an unprecedented dynamic range of cloud depth (AV = 3-60 mag). We compare deep Herschel-based measurements of dust extinction with observations of the 12CO, 13CO, and C18O J = 2 - 1 lines on sub-parsec scales …
Multiple Stellar Populations of Globular Clusters from Homogeneous Ca-CN-CH-NH Photometry. VI. M3 (NGC 5272) Is Not a Prototypical Normal Globular Cluster
Sneden, Christopher; Lee, Jae-Woo
We present Ca-CN-CH-NH photometry for the well-known globular cluster (GC) M3 (NGC 5272). We show new evidence for two M3 populations with distinctly different carbon and nitrogen abundances, seen in a sharp division between CN-weak and CN-strong red-giant branches (RGBs) in M3. The CN-strong population shows a C-N anticorrelation that is a natura…
Probing Protoplanetary Disk Winds with C II Absorption
Herczeg, Gregory J.; France, Kevin; Johns-Krull, Christopher M. +1 more
We present an analysis of wind absorption in the C II λ1335 doublet toward 40 classical T Tauri stars with archival far-ultraviolet (FUV) spectra obtained by the Hubble Space Telescope. Absorption features produced by fast or slow winds are commonly detected (36 out of 40 targets) in our sample. The wind velocity of the fast wind decreases with di…
A Deep Polarimetric Study of the Asymmetrical Debris Disk HD 106906
MacGregor, Meredith A.; Weinberger, Alycia J.; Debes, John H. +16 more
Located in the Lower Centaurus Crux group, HD 106906 is a young, binary stellar system. This system is unique among discovered systems in that it contains an asymmetrical debris disk, as well as an 11 MJup planet companion, at a separation of ~735 au. Only a handful of other systems are known to contain both a disk and a directly imaged…
Competitive X-Ray and Optical Cooling in the Collisionless Shocks of WR 140
Corcoran, M. F.; Russell, C. M. P.; Hamaguchi, K. +9 more
The long-period, highly eccentric Wolf-Rayet star binary system WR 140 has exceptionally well-determined orbital and stellar parameters. Bright, variable X-ray emission is generated in shocks produced by the collision of the winds of the WC7pd+O5.5fc component stars. We discuss the variations in the context of the colliding-wind model using broadb…
Self-organized Criticality in Stellar Flares
Güdel, Manuel; Aschwanden, Markus J.
Power-law size distributions are the hallmarks of nonlinear energy dissipation processes governed by self-organized criticality (SOC). Here we analyze 75 data sets of stellar flare size distributions, mostly obtained from the Extreme-Ultraviolet Explorer and the Kepler mission. We aim to answer the following questions for size distributions of ste…
The Search for Binary Supermassive Black Holes among Quasars with Offset Broad Lines Using the Very Long Baseline Array
Eracleous, Michael; Lazio, T. Joseph W.; Breiding, Peter +4 more
In several previous studies, quasars exhibiting broad emission lines with ≳1000 km s-1 velocity offsets with respect to the host galaxy rest frame have been discovered. One leading hypothesis for the origin of these velocity-offset broad lines is the dynamics of a binary supermassive black hole (SMBH). We present high-resolution radio i…
X-Ray Spectroscopy of the Highly Magnetized Pulsar PSR J1846-0258, Its Wind Nebula, and Hosting Supernova Remnant Kes 75
Gotthelf, E. V.; Safi-Harb, S.; Straal, S. M. +1 more
We present broadband X-ray spectroscopy of the energetic components that make up the supernova remnant (SNR) Kesteven 75 using concurrent 2017 August 17-20 XMM-Newton and NuSTAR observations, during which the pulsar PSR J1846-0258 is found to be in the quiescent state. The young remnant hosts a bright pulsar wind nebula powered by the highly energ…
Lyman Continuum Emission Escaping from Luminous Green Pea Galaxies at z = 0.5
Malkan, Matthew A.; Malkan, Brian K.
Compact starburst galaxies are thought to include many or most of the galaxies from which substantial Lyman continuum emission can escape into the intergalactic medium. Li & Malkan used Sloan Digital Sky Survey photometry to find a population of such starburst galaxies at z ∼ 0.5. They were discovered by their extremely strong [O III] λλ4959+5…
Measuring the Average Molecular Gas Content of Star-forming Galaxies at z = 3-4
Carilli, Chris; Feltre, Anna; Bacon, Roland +15 more
We study the molecular gas content of 24 star-forming galaxies at z = 3-4, with a median stellar mass of 109.1 M⊙, from the MUSE Hubble Ultra Deep Field (HUDF) Survey. Selected by their Lyα λ1216 emission and HF160W-band magnitude, the galaxies show an average $\langle {\mathrm{EW}}_{\mathrm{Ly}\alpha }^{0}\rangle …