Search Publications
The ALMA Spectroscopic Survey in the HUDF: CO Luminosity Functions and the Molecular Gas Content of Galaxies through Cosmic History
Carilli, Chris; Somerville, Rachel S.; Bacon, Roland +34 more
We use the results from the ALMA large program ASPECS, the spectroscopic survey in the Hubble Ultra Deep Field (HUDF), to constrain CO luminosity functions of galaxies and the resulting redshift evolution of ρ(H2). The broad frequency range covered enables us to identify CO emission lines of different rotational transitions in the HUDF …
Gaia-derived luminosities of Kepler A/F stars and the pulsator fraction across the δ Scuti instability strip
Bedding, Timothy R.; Murphy, Simon J.; Van Reeth, Timothy +1 more
We study the fraction of stars in and around the δ Scuti instability strip that are pulsating, using Gaia DR2 parallaxes to derive precise luminosities. We classify a sample of over 15 000 Kepler A and F stars into δ Sct and non-δ Sct stars, paying close attention to variability that could have other origins. We find that 18 per cent of the δ Sct …
Accuracy and Precision of Industrial Stellar Abundances
Jofré, Paula; Heiter, Ulrike; Soubiran, Caroline
There has been an incredibly large investment in obtaining high-resolution stellar spectra for determining chemical abundances of stars. This information is crucial to answer fundamental questions in astronomy by constraining the formation and evolution scenarios of the Milky Way as well as the stars and planets residing in it. We have just entere…
1ES 1927+654: An AGN Caught Changing Look on a Timescale of Months
Filippenko, Alexei V.; Remillard, Ronald A.; Rest, Armin +21 more
We study the sudden optical and ultraviolet (UV) brightening of 1ES 1927+654, which until now was known as a narrow-line active galactic nucleus (AGN). 1ES 1927+654 was part of the small and peculiar class of “true Type-2” AGNs that lack broad emission lines and line-of-sight obscuration. Our high-cadence spectroscopic monitoring captures the appe…
The Hubble Space Telescope PanCET Program: Exospheric Mg II and Fe II in the Near-ultraviolet Transmission Spectrum of WASP-121b Using Jitter Decorrelation
Nikolov, Nikolay; Mikal-Evans, Thomas; Sing, David K. +18 more
We present Hubble Space Telescope (HST) near-ultraviolet (NUV) transits of the hot Jupiter WASP-121b, acquired as part of the PanCET program. Time-series spectra during two transit events were used to measure the transmission spectra between 2280 and 3070 Å at a resolution of 30,000. Using HST data from 61 Space Telescope Imaging Spectrograph visi…
Mapping Metallicity Variations across Nearby Galaxy Disks
Chevance, M.; Meidt, S. E.; Schinnerer, E. +21 more
The distribution of metals within a galaxy traces the baryon cycle and the buildup of galactic disks, but the detailed gas phase metallicity distribution remains poorly sampled. We have determined the gas phase oxygen abundances for 7138 H II regions across the disks of eight nearby galaxies using Very Large Telescope/Multi Unit Spectroscopic Expl…
A stellar census in globular clusters with MUSE: Binaries in NGC 3201
Brinchmann, Jarle; Weilbacher, Peter M.; Kamann, Sebastian +8 more
We utilise multi-epoch MUSE spectroscopy to study binary stars in the core of the Galactic globular cluster NGC 3201. Our sample consists of 3553 stars with 54 883 spectra in total comprising 3200 main-sequence stars up to 4 magnitudes below the turn-off. Each star in our sample has between 3 and 63 (with a median of 14) reliable radial velocity m…
The mass of the Milky Way from satellite dynamics
Grand, Robert J. J.; Gómez, Facundo A.; Marinacci, Federico +6 more
We present and apply a method to infer the mass of the Milky Way (MW) by comparing the dynamics of MW satellites to those of model satellites in the EAGLE cosmological hydrodynamics simulations. A distribution function (DF) for galactic satellites is constructed from EAGLE using specific angular momentum and specific energy, which are scaled so as…
Constraining Primordial Black Hole Abundance with the Galactic 511 keV Line
DeRocco, William; Graham, Peter W.
Models in which dark matter consists entirely of primordial black holes (PBHs) with masses around 1 017 g are currently unconstrained. However, if PBHs are a component of the Galactic dark matter density, they will inject a large flux of energetic particles into the Galaxy as they radiate. Positrons produced by these black holes will su…
Do Kepler Superflare Stars Really Include Slowly Rotating Sun-like Stars?—Results Using APO 3.5 m Telescope Spectroscopic Observations and Gaia-DR2 Data
Notsu, Yuta; Maehara, Hiroyuki; Namekata, Kosuke +7 more
We report the latest view of Kepler solar-type (G-type main-sequence) superflare stars, including recent updates with Apache Point Observatory (APO) 3.5 m telescope spectroscopic observations and Gaia-DR2 data. First, we newly conducted APO 3.5 m spectroscopic observations of 18 superflare stars found from Kepler 1-minute time-cadence data. More t…