Search Publications
X-shooter observations of low-mass stars in the η Chamaeleontis association
Herczeg, Gregory; Fedele, Davide; Rugel, Michael
The nearby η Chamaeleontis association is a collection of 4-10 Myr old stars with a disk fraction of 35-45%. In this study, the broad wavelength coverage of VLT/X-shooter is used to measure the stellar and mass accretion properties of 15 low-mass stars in the η Chamaeleontis association. For each star, the observed spectrum is fitted with a non-ac…
Optical-Mid-infrared Period-Luminosity Relations for W UMa-type Contact Binaries Based on Gaia DR 1: 8% Distance Accuracy
Wang, Shu; Deng, Licai; de Grijs, Richard +2 more
W Ursa Majoris (W UMa)-type contact binary systems (CBs) are useful statistical distance indicators because of their large numbers. Here, we establish (orbital) period-luminosity relations (PLRs) in 12 optical to mid-infrared bands (GBVRIJHK s W1W2W3W4) based on 183 nearby W UMa-type CBs with accurate Tycho-Gaia parallaxes. The 1σ dispe…
Interplanetary Type II Radio Bursts from Wind/WAVES and Sustained Gamma-Ray Emission from Fermi/LAT: Evidence for Shock Source
Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji +4 more
We present quantitative evidence that interplanetary type II radio bursts and sustained gamma-ray emission (SGRE) events from the Sun are closely related. Out of about 30 SGRE events reported in Share et al. we consider 13 events that had a duration exceeding ∼5 hr to exclude any flare-impulsive phase gamma-rays. The SGRE duration also has a linea…
Total molecular gas masses of Planck - Herschel selected strongly lensed hyper luminous infrared galaxies
Magnelli, B.; Frayer, D. T.; Yun, M. S. +8 more
We report the detection of CO(1-0) line emission from seven Planck and Herschel selected hyper luminous ({L_{IR (8-1000{µ m})} > 10^{13} L_{⊙}) infrared galaxies with the Green Bank Telescope (GBT). CO(1-0) measurements are a vital tool to trace the bulk molecular gas mass across all redshifts. Our results place tight constraints on the t…
The split in the ancient cold front in the Perseus cluster
Fabian, Andy; Sanders, Jeremy; ZuHone, John +1 more
Sloshing cold fronts in clusters, produced as the dense cluster core moves around in the cluster potential in response to in-falling subgroups, provide a powerful probe of the physics of the intracluster medium and the magnetic fields permeating it1,2. These sharp discontinuities in density and temperature rise gradually outwards with a…
The Gaia-ESO Survey: Lithium enrichment histories of the Galactic thick and thin disc
Bayo, A.; Lardo, C.; Randich, S. +32 more
Lithium abundance in most of the warm metal-poor main sequence stars shows a constarnt plateau (A(Li) 2.2 dex) and then the upper envelope of the lithium vs. metallicity distribution increases as we approach solar metallicity. Meteorites, which carry information about the chemical composition of the interstellar medium (ISM) at the solar system fo…
Measuring growth index in a universe with massive neutrinos: A revisit of the general relativity test with the latest observations
Zhang, Jing-Fei; Zhang, Xin; Zhao, Ming-Ming
We make a consistency test for the general relativity (GR) through measuring the growth index γ in a universe with massive (sterile/active) neutrinos. We employ the redshift space distortion measurements to do the analysis. To constrain other cosmological parameters, we also use other cosmological measurements, including the Planck 2015 cosmic mic…
Speckle Interferometry at SOAR in 2016 and 2017
Tokovinin, Andrei; Horch, Elliott P.; Mason, Brian D. +2 more
The results of speckle interferometric observations at the 4.1 m Southern Astrophysical Research Telescope in 2016 and 2017 are given, totaling 2483 measurements of 1570 resolved pairs and 609 non-resolutions. We describe briefly recent changes in the instrument and observing method and quantify the accuracy of the pixel scale and position angle c…
Volans-Carina: A New 90 Myr Old Stellar Association at 85 pc
Faherty, Jacqueline K.; Gagné, Jonathan; Mamajek, Eric E.
We present a characterization of the new Volans-Carina Association (VCA) of stars near the Galactic plane (b ≃ -10°) at a distance of ≃75-100 pc, previously identified as group 30 by Oh et al. We compile a list of 19 likely members from Gaia DR2 with spectral types B8-M2, and 46 additional candidate members from Gaia DR2, 2MASS, and AllWISE with s…
Radial Velocities from the N2K Project: Six New Cold Gas Giant Planets Orbiting HD 55696, HD 98736, HD 148164, HD 203473, and HD 211810
Howard, Andrew W.; Fischer, Debra A.; Ment, Kristo +2 more
The N2K planet search program was designed to exploit the planet-metallicity correlation by searching for gas giant planets orbiting metal-rich stars. Here, we present the radial velocity measurements for 378 N2K target stars that were observed with the HIRES spectrograph at Keck Observatory between 2004 and 2017. With this data set, we announce t…