Search Publications
Age-dating Red Giant Stars Associated with Galactic Disk and Halo Substructures
Angus, Ruth; Huber, Daniel; Saunders, Nicholas +12 more
The vast majority of Milky Way stellar halo stars were likely accreted from a small number (≲3) of relatively large dwarf galaxy accretion events. However, the timing of these events is poorly constrained and predominantly relies on indirect dynamical mixing arguments or imprecise age measurements of stars associated with debris structures. Here, …
Selection Functions in Astronomical Data Modeling, with the Space Density of White Dwarfs as a Worked Example
Everall, Andrew; Boubert, Douglas; Hogg, David W. +6 more
Statistical studies of cataloged object properties are central to astrophysics. But one cannot model those objects' population properties without the sample's selection function, the quantitative understanding of which objects could have ended up in such a catalog. As didactic introductions to this topic are scarce in the astrophysical literature,…
The Red Supergiant Content of M31 and M33
Drout, Maria R.; Massey, Philip; Levesque, Emily M. +2 more
We identify red supergiants (RSGs) in our spiral neighbors M31 and M33 using near-IR (NIR) photometry complete to a luminosity limit of $\mathrm{log}L/{L}_{\odot }=4.0$ . Our archival survey data cover 5 deg2 of M31, and 3 deg2 for M33, and are likely spatially complete for these massive stars. Gaia is used to remove foregrou…
Revealing a High Water Abundance in the Upper Mesosphere of Mars With ACS Onboard TGO
Montmessin, Franck; Belyaev, Denis A.; Fedorova, Anna A. +7 more
We present the first water vapor profiles encompassing the upper mesosphere of Mars, 100-120 km, far exceeding the maximum altitudes where remote sensing has been able to observe water to date. Our results are based on solar occultation measurements by Atmospheric Chemistry Suite (ACS) onboard the ExoMars Trace Gas Orbiter (TGO). The observed wave…
The large-scale magnetic field of Proxima Centauri near activity maximum
Donati, Jean-François; Bonfils, Xavier; Delfosse, Xavier +5 more
We report the detection of a large-scale magnetic field at the surface of the slowly rotating fully convective (FC) M dwarf Proxima Centauri. 10 circular polarization spectra, collected from 2017 April to July with the HARPS-Pol spectropolarimeter, exhibit rotationally modulated Zeeman signatures suggesting a stellar rotation period of 89.8 ± 4.0 …
511 keV excess and primordial black holes
Hooper, Dan; Keith, Celeste
An excess of 511 keV photons has been detected from the central region of the Milky Way. It has been suggested that the positrons responsible for this signal might be produced through the Hawking evaporation of primordial black holes. After evaluating the constraints from INTEGRAL, COMPTEL, and Voyager 1, we find that black holes in mass range of …
Search for dormant black holes in ellipsoidal variables I. Revisiting the expected amplitudes of the photometric modulation
Gomel, Roy; Faigler, Simchon; Mazeh, Tsevi
Ellipsoidal variables present light-curve modulations caused by stellar distortion, induced by tidal interaction with their companions. An analytical approximated model of the ellipsoidal modulation is given as a discrete Fourier series by Morris & Naftilan. Based on numerical simulations using the PHOEBE code, we present here updated amplitud…
Gaia EDR3 in 6D: searching for unbound stars in the galaxy
Marchetti, Tommaso
The early third data release (EDR3) of the European Space Agency satellite Gaia provides coordinates, parallaxes, and proper motions for ∼1.47 billion sources in our Milky Way, based on 34 months of observations. The combination of Gaia DR2 radial velocities with the more precise and accurate astrometry provided by Gaia EDR3 makes the best data se…
A quantitative in-depth analysis of the prototype sdB+BD system SDSS J08205+0008 revisited in the Gaia era
Geier, S.; Dhillon, V. S.; Heber, U. +8 more
Subdwarf B stars are core-helium-burning stars located on the extreme horizontal branch (EHB). Extensive mass loss on the red giant branch is necessary to form them. It has been proposed that substellar companions could lead to the required mass loss when they are engulfed in the envelope of the red giant star. J08205+0008 was the first example of…
Jellyfish galaxy candidates in MACS J0717.5+3745 and 39 other clusters of the DAFT/FADA and CLASH surveys
Durret, F.; Jauzac, M.; Lobo, C. +1 more
Context. Galaxies in clusters undergo several phenomena, such as RPS and tidal interactions, that can trigger or quench their star formation and, in some cases, lead to galaxies acquiring unusual shapes and long tails - some become jellyfish.
Aims: We searched for jellyfish galaxy candidates in a sample of 40 clusters from the DAFT/FADA and C…