Search Publications
Back to the Lithium Plateau with the [Fe/H] < -6 Star J0023+0307
Aguado, David S.; Allende Prieto, Carlos; Rebolo, Rafael +1 more
We present an analysis of the Ultraviolet and Visual Echelle Spectrograph (UVES) high-resolution spectroscopic observations at the 8.2 m Very Large Telescope of J0023+0307, a main-sequence extremely iron-poor dwarf star. We are unable to detect iron lines in the spectrum but derive [Fe/H] < -6.1 from the Ca II resonance lines assuming [Ca/Fe] ≥…
The SPIRITS Sample of Luminous Infrared Transients: Uncovering Hidden Supernovae and Dusty Stellar Outbursts in Nearby Galaxies
Williams, Robert E.; Kilpatrick, Charles D.; Tinyanont, Samaporn +23 more
We present a systematic study of the most luminous (M IR [Vega magnitudes] brighter than -14) infrared (IR) transients discovered by the SPitzer InfraRed Intensive Transients Survey (SPIRITS) between 2014 and 2018 in nearby galaxies (D < 35 Mpc). The sample consists of nine events that span peak IR luminosities of M [4.5],peak
Spectrophotometric Parallaxes with Linear Models: Accurate Distances for Luminous Red-giant Stars
Hogg, David W.; Rix, Hans-Walter; Eilers, Anna-Christina
With contemporary infrared spectroscopic surveys like APO Galactic Evolution Experiment (APOGEE), red-giant stars can be observed to distances and extinctions at which Gaia parallaxes are not highly informative. Yet the combination of effective temperature, surface gravity, composition, and age—all accessible through spectroscopy—determines a gian…
Catalogues of active galactic nuclei from Gaia and unWISE data
McMahon, Richard G.; Belokurov, Vasily; Auger, Matthew W. +4 more
We present two catalogues of active galactic nucleus (AGN) candidates selected from the latest data of two all-sky surveys - Data Release 2 of the Gaia mission and the unWISE catalogue of the Wide-field Infrared Survey Explorer (WISE). We train a random forest classifier to predict the probability of each source in the Gaia-unWISE joint sample bei…
Extended halo of NGC 2682 (M 67) from Gaia DR2
Jordi, C.; Cantat-Gaudin, T.; Balaguer-Núñez, L. +8 more
Context. NGC 2682 is a nearby open cluster that is approximately 3.5 Gyr old. Dynamically, most open clusters are expected to dissolve on shorter timescales of ≈1 Gyr. That it has survived until now means that NGC 2682 was likely much more massive in the past and is bound to have an interesting dynamical history.
Aims: We investigate the spat…
Automated distant galaxy merger classifications from Space Telescope images using the Illustris simulation
Torrey, Paul; Rodriguez-Gomez, Vicente; Vogelsberger, Mark +5 more
We present image-based evolution of galaxy mergers from the Illustris cosmological simulation at 12 time-steps over 0.5 < z < 5. To do so, we created approximately one million synthetic deep Hubble Space Telescope and James Webb Space Telescope images and measured common morphological indicators. Using the merger tree, we assess methods to o…
Gaia Data Release 2 catalogue of extremely low-mass white dwarf candidates
Pelisoli, Ingrid; Vos, Joris
Extremely low-mass white dwarf stars (ELMs) are M < 0.3 M⊙ helium-core white dwarfs born either as a result of a common-envelope phase or after a stable Roche lobe overflow episode in a multiple system. The Universe is not old enough for ELMs to have formed through single-star evolution channels. As remnants of binary evolution, ELMs…
Machine-learning Regression of Stellar Effective Temperatures in the Second Gaia Data Release
Bai, Yu; Wang, Song; Liu, JiFeng +2 more
This paper reports on the application of the supervised machine-learning algorithm to the stellar effective temperature regression for the second Gaia data release, based on the combination of the stars in four spectroscopic surveys: the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, Sloan Extension for Galactic Understanding and Explo…
The COS CGM Compendium. II. Metallicities of the Partial and Lyman Limit Systems at z ≲ 1
Lehner, Nicolas; Howk, J. Christopher; O'Meara, John M. +3 more
We present the results from our COS circumgalactic medium (CGM) compendium (CCC), a survey of the CGM at z ≲ 1 using H I-selected absorbers with 15 < {log}{N}{{H}{{I}}} < 19. We focus here on 82 partial Lyman limit systems (pLLSs, 16.2 ≤ {log}{N}{{H}{{I}}} < 17.2) and 29 LLSs (17.2 ≤ {log}{N}{{H}{{I}}} <…
The High-Resolution Coronal Imager, Flight 2.1
Tiwari, Sanjiv K.; Golub, Leon; Winebarger, Amy R. +49 more
The third flight of the High-Resolution Coronal Imager (Hi-C 2.1) occurred on May 29, 2018; the Sounding Rocket was launched from White Sands Missile Range in New Mexico. The instrument has been modified from its original configuration (Hi-C 1) to observe the solar corona in a passband that peaks near 172 Å, and uses a new, custom-built low-noise …