Search Publications
High-resolution Optical Spectroscopy of Stars in the Sylgr Stellar Stream
Roederer, Ian U.; Gnedin, Oleg Y.
We observe two metal-poor main-sequence stars that are members of the recently discovered Sylgr stellar stream. We present radial velocities, stellar parameters, and abundances for 13 elements derived from high-resolution optical spectra collected using the Magellan Inamori Kyocera Echelle spectrograph. The two stars have identical compositions (w…
Spectroscopic Confirmation of Five Galaxy Clusters at z > 1.25 in the 2500 deg2 SPT-SZ Survey
Bayliss, M. B.; Sharon, K.; Gladders, M. D. +29 more
We present spectroscopic confirmation of five galaxy clusters at 1.25 < z < 1.5, discovered in the 2500 deg2 South Pole Telescope Sunyaev-Zel’dovich (SZ) survey. These clusters, taken from a mass-limited sample with a nearly redshift-independent selection function, have multiwavelength follow-up imaging data from the X-ray to near…
Effective Temperatures of Low-mass Stars from High-resolution H-band Spectroscopy
Kesseli, Aurora Y.; Muirhead, Philip S.; Johns-Krull, Christopher M. +9 more
High-resolution, near-infrared spectra will be the primary tool for finding and characterizing Earth-like planets around low-mass stars. Yet, the properties of exoplanets cannot be precisely determined without accurate and precise measurements of the host star. Spectra obtained with the Immersion Grating Infrared Spectrometer simultaneously provid…
Titan Surface Temperatures during the Cassini Mission
Flasar, F. M.; Coustenis, A.; Achterberg, R. K. +11 more
By the close of the Cassini mission in 2017 the Composite Infrared Spectrometer had recorded surface brightness temperatures on Titan for 13 yr (almost half a Titan year). We mapped temperatures in latitude from pole to pole in seven time segments from northern mid-winter to northern summer solstice. At the beginning of the mission the warmest tem…
Fast-cadence TESS Photometry and Doppler Tomography of the Asynchronous Polar CD Ind: A Revised Accretion Geometry from Newly Proposed Spin and Orbital Periods
Garnavich, Peter; Littlefield, Colin; Szkody, Paula +5 more
The Transiting Exoplanet Survey Satellite observed the asynchronous polar (AP) CD Ind at a 2 min cadence almost continuously for 28 days in 2018, covering parts of five consecutive cycles of the system’s 7.3 day beat period. These observations provide the first uninterrupted photometry of a full spin-orbit beat cycle of an AP. Twice per beat cycle…
The Acceleration of Energetic Particles at Coronal Shocks and Emergence of a Double Power-law Feature in Particle Energy Spectra
Chen, Yao; Giacalone, Joe; Guo, Fan +1 more
We present numerical modeling of particle acceleration at coronal shocks propagating through a streamer-like magnetic field by solving the Parker transport equation with spatial diffusion both along and across the magnetic field. We show that the location on the shock where the high-energy particle intensity is the largest, depends on the energy o…
Compact Star-forming Galaxies as Old Starbursts Becoming Quiescent
Ivison, R. J.; Gómez-Guijarro, C.; Magdis, G. E. +8 more
Optically compact star-forming galaxies (SFGs) have been proposed as immediate progenitors of quiescent galaxies, although their origin and nature are debated. Were they formed in slow secular processes or in rapid merger-driven starbursts? Answering this question would provide fundamental insight into how quenching occurs. We explore the location…
Relativistic Components of the Ultra-fast Outflow in the Quasar PDS 456 from Chandra/HETGS, NuSTAR, and XMM-Newton Observations
Danehkar, Ashkbiz; Nowak, Michael A.; Marshall, Herman L. +1 more
We present the spectral analysis of Chandra/High Energy Transmission Grating Spectrometer (HETGS) and NuSTAR observations of the quasar PDS 456 from 2015, and XMM-Newton and NuSTAR archival data from 2013 to 2014, together with Chandra/HETGS data from 2003. We analyzed these three different epochs in a consistent way, looking for absorption featur…
Search for Surviving Companions of Progenitors of Young LMC SN Ia Remnants
Leibundgut, Bruno; Pan, Kuo-Chuan; Ricker, Paul M. +9 more
We have used two methods to search for surviving companions of Type Ia supernova progenitors in three Balmer-dominated supernova remnants in the Large Magellanic Cloud: 0519-69.0, 0505-67.9 (DEM L71), and 0548-70.4. In the first method, we use the Hubble Space Telescope photometric measurements of stars to construct color-magnitude diagrams (CMDs)…
Comprehensive Analysis of the Formation of a Shock Wave Associated with a Coronal Mass Ejection
Susino, Roberto; Frassati, Federica; Mancuso, Salvatore +1 more
On 2014 November 1, a solar prominence eruption associated with a C2.7 class flare and a type II radio burst resulted in a fast partial halo coronal mass ejection (CME). Images acquired in the extreme ultraviolet (EUV) by the Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA) and PROBA2/SWAP and in white light (WL) by Solar and Heliosph…