Search Publications
The Variable Fast Soft X-Ray Wind in PG 1211+143
Reeves, J. N.; Pounds, K. A.; Lobban, A.
The analysis of a series of seven observations of the nearby (z = 0.0809) QSO PG 1211+143, taken with the Reflection Grating Spectrometer (RGS) onboard XMM-Newton in 2014, are presented. The high-resolution soft X-ray spectrum, with a total exposure exceeding 600 ks, shows a series of blueshifted absorption lines from the He and H-like transitions…
An Alternate Approach to Measure Specific Star Formation Rates at 2\lt z\lt 7
Ilbert, Olivier; Davidzon, Iary; Faisst, Andreas L. +2 more
We trace the specific star formation rate (sSFR) of massive star-forming galaxies (≳ {10}10 {{ M }}⊙ ) from z∼ 2 to 7. Our method is substantially different from previous analyses, as it does not rely on direct estimates of star formation rate, but on the differential evolution of the galaxy stellar mass function (SMF). We sh…
The Effect of Magnetic Variability on Stellar Angular Momentum Loss. I. The Solar Wind Torque during Sunspot Cycles 23 and 24
Finley, Adam J.; See, Victor; Matt, Sean P.
The rotational evolution of cool stars is governed by magnetized stellar winds that slow the stellar rotation during their main sequence lifetimes. Magnetic variability is commonly observed in Sun-like stars, and the changing strength and topology of the global field is expected to affect the torque exerted by the stellar wind. We present three di…
ALMA Detections of CO Emission in the Most Luminous, Heavily Dust-obscured Quasars at z > 3
Knudsen, Kirsten K.; Drouart, Guillaume; Fan, Lulu +1 more
We report the results of a pilot study of CO(4 - 3) emission line of three Wide-field Infrared Survey Explorer (WISE)-selected hyper-luminous, dust-obscured quasars (QSOs) with sensitive ALMA Band 3 observations. These obscured QSOs with L bol > 1014 L ⊙ are among the most luminous objects in the universe. All t…
Effective Induction Heating around Strongly Magnetized Stars
Lammer, H.; Fossati, L.; Lüftinger, T. +4 more
Planets that are embedded in the changing magnetic fields of their host stars can experience significant induction heating in their interiors caused by the planet’s orbital motion. For induction heating to be substantial, the planetary orbit has to be inclined with respect to the stellar rotation and dipole axes. Using WX UMa, for which the rotati…
Resolved Kinematics of Runaway and Field OB Stars in the Small Magellanic Cloud
Lennon, D. J.; Oey, M. S.; Castro, N. +6 more
We use Gaia Data Release 2 proper motions of field OB stars from the Runaways and Isolated O-Type Star Spectroscopic Survey of the Small Magellanic Cloud (SMC) to study the kinematics of runaway stars. The data reveal that the SMC Wing has a systemic peculiar motion relative to the SMC Bar of ({v}α ,{v}δ ) =(62+/- 7,-18+/- 5)…
The Charge State of Polycyclic Aromatic Hydrocarbons across a Reflection Nebula, an H II Region, and a Planetary Nebula
Boersma, C.; Allamandola, L. J.; Bregman, J.
Low-resolution Spitzer-IRS spectral map data of a reflection nebula (NGC 7023), H II region (M17), and planetary nebula (NGC 40), totaling 1417 spectra, are analyzed using the data and tools available through the NASA Ames PAH IR Spectroscopic Database. The polycyclic aromatic hydrocarbon (PAH) emission is broken down into PAH charge and size subc…
Accretion Disk Size Measurement and Time Delays in the Lensed Quasar WFI 2033-4723
Kochanek, Christopher S.; Bonvin, Vivien; Courbin, Frederic +5 more
We present 13 seasons of R-band photometry of the quadruply lensed quasar WFI 2033-4723 from the 1.3 m SMARTS telescope at CTIO and the 1.2 m Euler Swiss Telescope at La Silla, in which we detect microlensing variability of ∼0.2 mag on a timescale of ∼6 years. Using a Bayesian Monte Carlo technique, we analyze the microlensing signal to obtain a m…
Nearby High-speed Stars in Gaia DR2
Geller, Margaret J.; Brown, Warren R.; Kenyon, Scott J. +1 more
We investigate the nature of nearby (10-15 kpc) high-speed stars in the Gaia DR2 archive identified on the basis of parallax, proper motion and radial velocity. Together with a consideration of their kinematic, orbital, and photometric properties, we develop a novel strategy for evaluating whether high-speed stars are statistical outliers of the b…
On the Stellar Velocity Distribution in the Solar Neighborhood in Light of Gaia DR2
Pérez-Villegas, Angeles; Barros, Douglas A.; Michtchenko, Tatiana A. +2 more
The aim of this Letter is to contribute to the understanding of the stellar velocity distribution in the solar neighborhood (SN). We propose that the structures on the U-V planes, known as the moving groups, can be mainly explained by the spiral arms perturbations. The applied model of the Galactic disk and spiral arms, with the parameters defined…