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The AMBRE project: The thick thin disk and thin thick disk of the Milky Way
Recio-Blanco, A.; de Laverny, P.; Hayden, M. R. +2 more
We analyze 494 main sequence turnoff and subgiant stars from the AMBRE:HARPS survey. These stars have accurate astrometric information from Gaia DR1, providing reliable age estimates with relative uncertainties of ±1 or 2 Gyr and allowing precise orbital determinations. The sample is split based on chemistry into a low-[Mg/Fe] sequence, which are …
Rotation of Late-type Stars in Praesepe with K2
Bouvier, J.; Hebb, L.; Rebull, L. M. +5 more
We have Fourier-analyzed 941 K2 light curves (LCs) of likely members of Praesepe, measuring periods for 86% and increasing the number of rotation periods (P) by nearly a factor of four. The distribution of P versus (V-{K}{{s}}), a mass proxy, has three different regimes: (V-{K}{{s}}) < 1.3, where the rotation rate rapidly …
Galactocentric variation of the gas-to-dust ratio and its relation with metallicity
König, C.; Menten, K. M.; Leurini, S. +6 more
Context. The assumption of a gas-to-dust mass ratio γ is a common approach to estimate the basic properties of molecular clouds, such as total mass and column density of molecular hydrogen, from (sub)mm continuum observations of the dust. In the Milky Way a single value is used at all galactocentric radii, independently of the observed metallicity…
An elevation of 0.1 light-seconds for the optical jet base in an accreting Galactic black hole system
Harrison, F. A.; Stern, D.; Altamirano, D. +25 more
Relativistic plasma jets are observed in many systems that host accreting black holes. According to theory, coiled magnetic fields close to the black hole accelerate and collimate the plasma, leading to a jet being launched1-3. Isolating emission from this acceleration and collimation zone is key to measuring its size and understanding …
Mapping the Nuclear Outflow of the Milky Way: Studying the Kinematics and Spatial Extent of the Northern Fermi Bubble
Jenkins, Edward B.; Hernandez, Svea; Savage, Blair D. +7 more
We report new observations from a systematic, spectroscopic, ultraviolet absorption-line survey that maps the spatial and kinematic properties of the high velocity gas in the Galactic Center (GC) region. We examine the hypothesis that this gas traces the biconical nuclear outflow. We use an ultraviolet spectra of 47 background QSOs and halo stars …
Cosmological discordances. II. Hubble constant, Planck and large-scale-structure data sets
Ishak, Mustapha; Lin, Weikang
We examine systematically the (in)consistency between cosmological constraints as obtained from various current data sets of the expansion history, large-scale-structure (LSS), and cosmic microwave background (CMB) temperature and polarization from Planck. We run (dis)concordance tests within each set and across the three sets using a recently int…
Statistical Analysis of Hubble/WFC3 Transit Spectroscopy of Extrasolar Planets
Deming, Drake; Madhusudhan, Nikku; Knutson, Heather +3 more
Transmission spectroscopy provides a window to study exoplanetary atmospheres, but that window is fogged by clouds and hazes. Clouds and haze introduce a degeneracy between the strength of gaseous absorption features and planetary physical parameters such as abundances. One way to break that degeneracy is via statistical studies. We collect all pu…
The Extended IRTF Spectral Library: Expanded Coverage in Metallicity, Temperature, and Surface Gravity
van Dokkum, Pieter; Conroy, Charlie; Mann, Andrew W. +3 more
We present a 0.7-2.5 µm spectral library of 284 stars observed with the medium-resolution infrared spectrograph, SpeX, at the 3.0 m NASA Infrared Telescope Facility (IRTF) on Maunakea, Hawaii. This library extends the metallicity range of the IRTF Cool Star library beyond solar metallicity to -1.7 < [Fe/H] < 0.6. All of the observed st…
Black Hole Growth Is Mainly Linked to Host-galaxy Stellar Mass Rather Than Star Formation Rate
Lehmer, B. D.; Alexander, D. M.; Bauer, F. E. +14 more
We investigate the dependence of black hole accretion rate (BHAR) on host-galaxy star formation rate (SFR) and stellar mass (M *) in the CANDELS/GOODS-South field in the redshift range of 0.5≤slant z< 2.0. Our sample consists of ≈ {{18,000}} galaxies, allowing us to probe galaxies with 0.1{M}⊙ {{yr}}-1≲ {SFR}≲ 1…
Distance and Properties of NGC 4993 as the Host Galaxy of the Gravitational-wave Source GW170817
Lee, Chung-Uk; Kim, Seung-Lee; Im, Myungshin +9 more
Recently, the optical counterpart of the gravitational-wave source GW170817 has been identified in the NGC 4993 galaxy. Together with evidence from observations in electromagnetic waves, the event has been suggested as a result of a merger of two neutron stars (NSs). We analyze the multi-wavelength data to characterize the host galaxy property and…