Search Publications
A plethora of new, magnetic chemically peculiar stars from LAMOST DR4
Paunzen, E.; Bernhard, K.; Hümmerich, S.
Context. Magnetic chemically peculiar (mCP) stars are important to astrophysics because their complex atmospheres lend themselves perfectly to the investigation of the interplay between such diverse phenomena as atomic diffusion, magnetic fields, and stellar rotation. The most up-to-date catalogue of these objects was published a decade ago. Since…
The Multiplanet System TOI-421
Henning, Thomas; Butler, R. Paul; Hellier, Coel +110 more
We report the discovery of a warm Neptune and a hot sub-Neptune transiting TOI-421 (BD-14 1137, TIC 94986319), a bright (V = 9.9) G9 dwarf star in a visual binary system observed by the Transiting Exoplanet Survey Satellite (TESS) space mission in Sectors 5 and 6. We performed ground-based follow-up observations—comprised of Las Cumbres Observator…
The Stellar Velocity Distribution Function in the Milky Way Galaxy
Majewski, Steven R.; Beers, Timothy C.; Hayes, Christian R. +6 more
The stellar velocity distribution function in the solar vicinity is reexamined using data from the Sloan Digital Sky Survey Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey's DR16 and Gaia DR2. By exploiting APOGEE's ability to chemically discriminate with great reliability the thin-disk, thick-disk, and (accreted) halo popul…
The stellar and wind parameters of six prototypical HMXBs and their evolutionary status
Hamann, W. -R.; Oskinova, L. M.; Sander, A. A. C. +7 more
Context. High-mass X-ray binaries (HMXBs) are exceptional astrophysical laboratories that offer a rare glimpse into the physical processes that govern accretion on compact objects, massive-star winds, and stellar evolution. In a subset of the HMXBs, the compact objects accrete matter solely from winds of massive donor stars. These so-called wind-f…
Carbon stars as standard candles: I. The luminosity function of carbon stars in the Magellanic Clouds
Heyl, Jeremy; Richer, Harvey; Ripoche, Paul +1 more
Our goal in this paper is to derive a carbon-star luminosity function that will eventually be used to determine distances to galaxies at 50-60 Mpc and hence yield a value of the Hubble constant. Cool N-type carbon stars exhibit redder near-infrared colours than oxygen-rich stars. Using Two Micron All Sky Survey near-infrared photometry and the Gai…
Open Cluster Chemical Homogeneity throughout the Milky Way
Beaton, Rachael L.; Hawkins, K.; Cunha, K. +10 more
The chemical homogeneity of surviving stellar clusters contains important clues about interstellar medium (ISM) mixing efficiency, star formation, and the enrichment history of the Galaxy. Existing measurements in a handful of open clusters suggest homogeneity in several elements at the 0.03 dex level. Here we present (i) a new cluster member cata…
Assessment of InSight Landing Site Predictions
Golombek, M.; Williams, N.; Charalambous, C. +5 more
Comprehensive analysis of remote sensing data used to select the Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) landing site correctly predicted the atmospheric temperature and pressure profile during entry and descent, the safe landing surface, and the geologic setting of the site. The smooth plains upon w…
ALMA resolves the remarkable molecular jet and rotating wind in the extremely radio-quiet galaxy NGC 1377
Gallagher, J. S.; van der Werf, P.; Combes, F. +14 more
Submillimetre and millimetre line and continuum observations are important in probing the morphology, column density, and dynamics of the molecular gas and dust around obscured active galactic nuclei (AGNs) and their mechanical feedback. With very high-resolution (0.″02 × 0.″03 (2 × 3 pc)) ALMA 345 GHz observations of CO 3-2, HCO+ 4-3, …
Transport of angular momentum by stochastically excited waves as an explanation for the outburst of the rapidly rotating Be star HD49330
Neiner, C.; Lee, U.; Mathis, S. +3 more
Context. HD 49330 is an early Be star that underwent an outburst during its five-month observation with the CoRoT satellite. An analysis of its light curve revealed several independent p and g pulsation modes, in addition to showing that the amplitude of the modes is directly correlated with the outburst.
Aims: We modelled the results obtaine…
Discovering the most elusive radio relic in the sky: diffuse shock acceleration caught in the act?
Gastaldello, Fabio; Brunetti, Gianfranco; Dallacasa, Daniele +9 more
The origin of radio relics is usually explained via diffusive shock acceleration (DSA) or re-acceleration of electrons at/from merger shocks in galaxy clusters. The case of acceleration is challenged by the low predicted efficiency of low Mach number merger shocks, unable to explain the power observed in most radio relics. In this letter, we prese…