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Towards an astronomical foundation model for stars with a transformer-based model
Bovy, Jo; Leung, Henry W.
Rapid strides are currently being made in the field of artificial intelligence using transformer-based models like Large Language Models (LLMs). The potential of these methods for creating a single, large, versatile model in astronomy has not yet been explored. In this work, we propose a framework for data-driven astronomy that uses the same core …
Discovery of the local counterpart of disc galaxies at z > 4: The oldest thin disc of the Milky Way using Gaia-RVS
Guiglion, G.; Chiappini, C.; Queiroz, A. B. +5 more
Context. JWST recently detected numerous disc galaxies at high redshifts, and there have been observations of cold disc galaxies at z > 4 with ALMA. In the Milky Way (MW), recent studies highlight the presence of metal-poor stars in cold-disc orbits, suggesting an ancient disc. This prompts two fundamental questions. The first refers to the tim…
High turbulence in the IM Lup protoplanetary disk. Direct observational constraints from CN and C2H emission
Miotello, A.; van Dishoeck, E. F.; Bergin, E. A. +4 more
Context. Constraining turbulence in disks is key to understanding their evolution via the transport of angular momentum. Measurements of high turbulence remain elusive, and methods for estimating turbulence mostly rely on complex radiative transfer models of the data. Using the disk emission from IM Lup, a source proposed to be undergoing magneto-…
A magnetic massive star has experienced a stellar merger
Smoker, J. V.; Shenar, T.; Sana, H. +13 more
Massive stars (those ≥8 solar masses at formation) have radiative envelopes that cannot sustain a dynamo, the mechanism that produces magnetic fields in lower-mass stars. Despite this, approximately 7% of massive stars have observed magnetic fields, the origin of which is debated. We used multi-epoch interferometric and spectroscopic observations …
Achievement of the Planetary Defense Investigations of the Double Asteroid Redirection Test (DART) Mission
Buratti, Bonnie J.; Kolokolova, Ludmilla; Zinzi, Angelo +126 more
NASA's Double Asteroid Redirection Test (DART) mission was the first to demonstrate asteroid deflection, and the mission's Level 1 requirements guided its planetary defense investigations. Here, we summarize DART's achievement of those requirements. On 2022 September 26, the DART spacecraft impacted Dimorphos, the secondary member of the Didymos n…
Constraining primordial non-Gaussianity from DESI quasar targets and Planck CMB lensing
Miquel, Ramon; Font-Ribera, Andreu; Yèche, Christophe +33 more
We detect the cross-correlation between 2.7 million DESI quasar targets across 14,700 deg2 (180 quasars deg-2) and Planck 2018 CMB lensing at ∼30σ. We use the cross-correlation on very large scales to constrain local primordial non-Gaussianity via the scale dependence of quasar bias. The DESI quasar targets lie at an effectiv…
Initial-final mass relation from white dwarfs within 40 pc
Tremblay, Pier-Emmanuel; Cunningham, Tim; W. O'Brien, Mairi
We present an initial-final mass relation derived from the spectroscopically complete volume-limited 40 pc sample of white dwarfs. The relation is modelled using population synthesis methods to derive an initial stellar population which can be fit to the observed mass distribution of white dwarfs. The population synthesis accounts for binary evolu…
Apache Point Observatory (APO)/SMARTS Flare Star Campaign Observations. I. Blue Wing Asymmetries in Chromospheric Lines during Mid-M-Dwarf Flares from Simultaneous Spectroscopic and Photometric Observation Data
Hamaguchi, Kenji; Notsu, Yuta; Kowalski, Adam F. +12 more
We conducted the time-resolved simultaneous optical spectroscopic and photometric observations of mid-M-dwarf flare stars YZ CMi, EV Lac, and AD Leo. Spectroscopic observations were obtained using Apache Point Observatory 3.5 m and Small and Moderate Aperture Research Telescope System 1.5 m telescopes during 31 nights. Among the 41 detected flares…
Resolved Measurements of the CO-to-H2 Conversion Factor in 37 Nearby Galaxies
Sandstrom, Karin M.; Bolatto, Alberto D.; Leroy, Adam K. +6 more
We measure the CO-to-H2 conversion factor (α CO) in 37 galaxies at 2 kpc resolution, using the dust surface density inferred from far-infrared emission as a tracer of the gas surface density and assuming a constant dust-to-metal ratio. In total, we have ∼790 and ∼610 independent measurements of α CO for CO (2–1) an…
Radial halo substructure in harmony with the Galactic bar
Belokurov, Vasily; Evans, N. Wyn; Dillamore, Adam M.
Overdensities in the radial phase space $(r,v_{\rm r})$ of the Milky Way's halo have previously been associated with the phase-mixed debris of a highly radial merger event such as Gaia Sausage-Enceladus. We present and test an alternative theory in which the overdense 'chevrons' are instead composed of stars trapped in resonances with the Galactic…