Search Publications
Luminosity Models and Density Profiles for Nuclear Star Clusters for a Nearby Volume-limited Sample of 29 Galaxies
Pechetti, Renuka; Neumayer, Nadine; Kacharov, Nikolay +3 more
Nuclear star clusters (NSCs) are dense stellar clusters that are found at the centers of a majority of galaxies. In this paper, we study the density profiles for 29 galaxies in a volume-limited survey within 10 Mpc to characterize their NSCs. These galaxies span a 3 × 108-8 × 1010 M⊙ and a wide range of Hubble type…
First Gaia dynamical model of the Milky Way disc with six phase space coordinates: a test for galaxy dynamics
Neumayer, Nadine; Cappellari, Michele; Nitschai, Maria Selina
We construct the first comprehensive dynamical model for the high-quality subset of stellar kinematics of the Milky Way disc, with full 6D phase-space coordinates, provided by the Gaia Data Release 2. We adopt an axisymmetric approximation and use an updated Jeans Anisotropic Modelling (JAM) method, which allows for a generic shape and radial orie…
The First Habitable-zone Earth-sized Planet from TESS. II. Spitzer Confirms TOI-700 d
Barclay, Thomas; Vanderburg, Andrew; Latham, David W. +43 more
We present Spitzer 4.5 µm observations of the transit of TOI-700 d, a habitable-zone Earth-sized planet in a multiplanet system transiting a nearby M-dwarf star (TIC 150428135, 2MASS J06282325-6534456). TOI-700 d has a radius of ${1.144}_{-0.061}^{+0.062}{R}_{\oplus }$ and orbits within its host star's conservative habitable zone with a peri…
The Dynamics of Interstellar Asteroids and Comets within the Galaxy: An Assessment of Local Candidate Source Regions for 1I/'Oumuamua and 2I/Borisov
Hallatt, Tim; Wiegert, Paul
The low velocity of interstellar asteroid 1I/'Oumuamua with respect to our galaxy's local standard of rest implies that it is young. Adopting the young age hypothesis, we assess possible origin systems for this interstellar asteroid and for 2I/Borisov, though the latter's higher speed means it is unlikely to be young. First, their past trajectorie…
Corona-Australis DANCe. I. Revisiting the census of stars with Gaia-DR2 data
Miret-Roig, N.; Bouy, H.; Sarro, L. M. +5 more
Context. Corona-Australis is one of the nearest regions to the Sun with recent and ongoing star formation, but the current picture of its stellar (and substellar) content is not complete yet.
Aims: We take advantage of the second data release of the Gaia space mission to revisit the stellar census and search for additional members of the youn…
NGTS clusters survey - I. Rotation in the young benchmark open cluster Blanco 1
Jackman, James A. G.; Wheatley, Peter J.; Foreman-Mackey, Daniel +18 more
We determine rotation periods for 127 stars in the ∼115-Myr-old Blanco 1 open cluster using ∼200 d of photometric monitoring with the Next Generation Transit Survey. These stars span F5-M3 spectral types (1.2 M⊙ ≳ M ≳ 0.3 M⊙) and increase the number of known rotation periods in Blanco 1 by a factor of four. We determine rotat…
APOGEE Net: Improving the Derived Spectral Parameters for Young Stars through Deep Learning
Stassun, Keivan G.; Kounkel, Marina; Covey, K. R. +6 more
Machine learning allows for efficient extraction of physical properties from stellar spectra that have been obtained by large surveys. The viability of machine-learning approaches has been demonstrated for spectra covering a variety of wavelengths and spectral resolutions, but most often for main-sequence (MS) or evolved stars, where reliable synt…
From hydrogen to helium: the spectral evolution of white dwarfs as evidence for convective mixing
Hollands, Mark; Gentile Fusillo, Nicola Pietro; Tremblay, Pier-Emmanuel +2 more
We present a study of the hypothesis that white dwarfs undergo a spectral change from hydrogen- to helium-dominated atmospheres using a volume-limited photometric sample drawn from the Gaia-DR2 catalogue, the Sloan Digital Sky Survey (SDSS), and the Galaxy Evolution Explorer (GALEX). We exploit the strength of the Balmer jump in hydrogen-atmospher…
A New Class of Roche Lobe-filling Hot Subdwarf Binaries
Duev, Dmitry A.; Szkody, Paula; Littlefair, S. P. +30 more
We present the discovery of the second binary with a Roche lobe-filling hot subdwarf transferring mass to a white dwarf (WD) companion. This 56 minute binary was discovered using data from the Zwicky Transient Facility. Spectroscopic observations reveal an He-sdOB star with an effective temperature of Teff = 33,700 ± 1000 K and a surfac…
HAZMAT VI: The Evolution of Extreme Ultraviolet Radiation Emitted from Early M Stars
Loyd, R. O. Parke; Peacock, Sarah; Barman, Travis +4 more
Quantifying the evolution of stellar extreme ultraviolet (EUV, 100-1000 Å) emission is critical for assessing the evolution of planetary atmospheres and the habitability of M dwarf systems. Previous studies from the HAbitable Zones and M dwarf Activity across Time (HAZMAT) program showed the far- and near-UV (FUV, NUV) emission from M stars at var…