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A Volume-limited Sample of Ultracool Dwarfs. II. The Substellar Age and Mass Functions in the Solar Neighborhood
Magnier, Eugene A.; Dupuy, Trent J.; Liu, Michael C. +2 more
We present the most precise constraints to date for the mass and age distributions of single ultracool dwarfs in the solar neighborhood, based on an updated volume-limited sample of 504 L, T, and Y dwarfs within 25 pc. We develop a Monte Carlo approach using the $\langle V/{V}_{\max }\rangle $ statistic to correct for incompleteness and obtain a s…
K2 results for "young" α-rich stars in the Galaxy
Valentini, M.; Chiappini, C.; Tailo, M. +11 more
Context. The origin of apparently young α-rich stars in the Galaxy is still a matter of debate in Galactic archaeology, whether they are genuinely young or might be products of binary evolution, and mergers or mass accretion.
Aims: Our aim is to shed light on the nature of young α-rich stars in the Milky Way by studying their distribution in …
MINDS: The DR Tau disk: II. Probing the hot and cold H2O reservoirs in the JWST-MIRI spectrum
Henning, Thomas; Güdel, Manuel; Tabone, Benoît +14 more
Context. The Medium Resolution Spectrometer (MRS) of the Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST) gives insights into the chemical richness and complexity of the inner regions of planet-forming disks. Several disks that are compact in the millimetre dust emission have been found by Spitzer to be particularly bright i…
The MeerKAT 1.3 GHz Survey of the Small Magellanic Cloud
Haberl, F.; Filipović, M. D.; Indebetouw, R. +22 more
We present new radio continuum images and a source catalogue from the MeerKAT survey in the direction of the Small Magellanic Cloud. The observations, at a central frequency of 1.3 GHz across a bandwidth of 0.8 GHz, encompass a field of view ~7° × 7° and result in images with resolution of 8 arcsec. The median broad-band Stokes I image Root Mean S…
The Extremely Metal-rich Knot of Stars at the Heart of the Galaxy
Pillepich, Annalisa; Laporte, Chervin F. P.; Rix, Hans-Walter +15 more
We show with Gaia XP spectroscopy that extremely metal-rich (EMR) stars in the Milky Way ([M/H]XP ≳ 0.5) are largely confined to a tight "knot" at the center of the Galaxy. This EMR knot is round in projection, has a fairly abrupt edge near R GC,proj ∼ 1.5 kpc, and is a dynamically hot system. This central knot also contains …
A Deficit of Massive White Dwarfs in Gaia Astrometric Binaries
Hallakoun, Na'ama; Toonen, Silvia; Mazeh, Tsevi +2 more
The third data release of Gaia introduced a large catalog of astrometric binaries, out of which about 3200 are likely main-sequence stars with a white dwarf (WD) companion. These binaries are typically found with orbital separations of ∼1 au, a separation range that was largely unexplored due to observational challenges. Such systems are likely to…
TOI-4201: An Early M Dwarf Hosting a Massive Transiting Jupiter Stretching Theories of Core Accretion
Butler, R. Paul; Mahadevan, Suvrath; Wright, Jason T. +27 more
We confirm TOI-4201 b as a transiting Jovian-mass planet orbiting an early M dwarf discovered by the Transiting Exoplanet Survey Satellite. Using ground-based photometry and precise radial velocities from NEID and the Planet Finder Spectrograph, we measure a planet mass of ${2.59}_{-0.06}^{+0.07}$ M J, making this one of the most massiv…
Ultradiffuse Galaxies—A Distinct Population? Dwarf Galaxies in the Coma Cluster and A262 from Deep u'–g'–r' Wendelstein Imaging Data
Bender, Ralf; Kluge, Matthias; Zöller, Raphael +1 more
In this study, we compare the structural parameters of ultradiffuse galaxies (UDGs) to those of other dwarf galaxies and investigate whether UDGs form a distinct population. We observed deep $u^{\prime} $ -, $g^{\prime} $ -, and $r^{\prime} $ -band images (maximum limiting surface brightness [3σ, 10″ × 10″] $u^{\prime} $ and $g^{\prime} $ : $\appr…
Repeating nuclear transients as candidate electromagnetic counterparts of LISA extreme mass ratio inspirals
Pasham, Dheeraj R.; Zajaček, Michal; Witzany, Vojtěch +2 more
Extreme mass ratio inspirals (EMRIs) are one of the primary targets for the recently adopted millihertz gravitational-wave observatory LISA. Some previous studies have argued that a fraction of all EMRIs form in matter-rich environments, and can potentially explain the dozens of soft X-ray band ($\sim 10^{-1}\,\rm keV$), low-frequency ($\sim 0.1$ …
An absence of binary companions to Wolf-Rayet stars in the Small Magellanic Cloud: Implications for mass loss and black hole masses at low metallicities
Wang, C.; Shenar, T.; Sana, H. +6 more
To predict black hole mass distributions at high redshifts, we need to understand whether very massive single stars (M ≳ 40 M⊙) with low metallicities (Z) lose their hydrogen-rich envelopes, like their metal-rich counterparts, or whether a binary companion is required to achieve this. To test this, we undertook a deep spectroscopic sear…