Search Publications
The relativistic jet dichotomy and the end of the blazar sequence
Georganopoulos, Markos; Meyer, Eileen T.; Reddy, Karthik +2 more
Our understanding of the unification of jetted AGN has evolved greatly as jet samples have increased in size. Here, based on the largest-ever sample of over 2000 well-sampled jet spectral energy distributions, we examine the synchrotron peak frequency - peak luminosity plane, and find little evidence for the anticorrelation known as the blazar seq…
Stellar Metallicities from SkyMapper Photometry. II. Precise Photometric Metallicities of ∼280,000 Giant Stars with [Fe/H] < -0.75 in the Milky Way
Frebel, Anna; Mardini, Mohammad K.; Chiti, Anirudh +3 more
The Milky Way's metal-poor stars are nearby ancient objects that are used to study early chemical evolution and the assembly and structure of the Milky Way. Here we present reliable metallicities of ∼280,000 stars with -3.75 ≲ [Fe/H] ≲ -0.75 down to g = 17 derived using metallicity-sensitive photometry from the second data release of the SkyMapper…
Constraints on the mass and on the atmospheric composition and evolution of the low-density young planet DS Tucanae A b
Borsa, F.; Micela, G.; Damasso, M. +9 more
Context. Observations of young close-in exoplanets are providing initial indications for the characteristics of the population and clues to the early stages of their evolution. Transiting planets at young ages are also key benchmarks for our understanding of planetary evolution via the verification of atmospheric escape models.
Aims: We perfo…
Photochemistry and Spectral Characterization of Temperate and Gas-rich Exoplanets
Hu, Renyu
Exoplanets that receive stellar irradiance approximately equal to Earth's or less have been discovered and many are suitable for spectral characterization. Here, we focus on the temperate planets that have massive H2-dominated atmospheres, and trace the chemical reactions and transport following the photodissociation of H2O, …
Cometary Activity Begins at Kuiper Belt Distances: Evidence from C/2017 K2
Mutchler, Max; Jewitt, David; Agarwal, Jessica +3 more
We study the development of activity in the incoming long-period comet C/2017 K2 over the heliocentric distance range 9 ≲ rH ≲ 16 au. The comet continues to be characterized by a coma of submillimeter-sized and larger particles ejected at low velocity. In a fixed co-moving volume around the nucleus we find that the scattering cross sect…
TOI-811b and TOI-852b: New Transiting Brown Dwarfs with Similar Masses and Very Different Radii and Ages from the TESS Mission
Latham, David W.; Quinn, Samuel N.; Stassun, Keivan G. +30 more
We report the discovery of two transiting brown dwarfs (BDs), TOI-811b and TOI-852b, from NASA's Transiting Exoplanet Survey Satellite mission. These two transiting BDs have similar masses but very different radii and ages. Their host stars have similar masses, effective temperatures, and metallicities. The younger and larger transiting BD is TOI-…
Discovery of an Ultra-faint Stellar System near the Magellanic Clouds with the DECam Local Volume Exploration Survey
James, D. J.; Kuropatkin, N.; Li, T. S. +30 more
We report the discovery of a new ultra-faint stellar system found near the Magellanic Clouds in the DECam Local Volume Exploration Survey. This new system, DELVE J0155-6815 (DELVE 2), is located at a heliocentric distance of D⊙ = 71 ± 4 kpc, which places it at a 3D physical separation of 12 ± 3 kpc from the center of the Small Magellani…
CO Excitation, Molecular Gas Density, and Interstellar Radiation Field in Local and High-redshift Galaxies
Daddi, Emanuele; Schinnerer, Eva; Liu, Daizhong +9 more
We study the carbon monoxide (CO) excitation, mean molecular gas density, and interstellar radiation field (ISRF) intensity in a comprehensive sample of 76 galaxies from local to high redshift (z ∼ 0-6), selected based on detections of their CO transitions J = 2 → 1 and 5 → 4 and their optical/infrared/(sub)millimeter spectral energy distributions…
The First Dynamical Mass Measurement in the HR 8799 System
Dupuy, Trent J.; Brandt, Timothy D.; Brandt, G. Mirek +2 more
HR 8799 hosts four directly imaged giant planets, but none has a mass measured from first principles. We present the first dynamical mass measurement in this planetary system, finding that the innermost planet HR 8799 e has a mass of ${9.6}_{-1.8}^{+1.9}\,{M}_{\mathrm{Jup}}$ . This mass results from combining the well-characterized orbits of all f…
Star cluster classification in the PHANGS-HST survey: Comparison between human and machine learning approaches
Van Dyk, Schuyler D.; Kruijssen, J. M. Diederik; Rosolowsky, Erik +21 more
When completed, the PHANGS-HST project will provide a census of roughly 50 000 compact star clusters and associations, as well as human morphological classifications for roughly 20 000 of those objects. These large numbers motivated the development of a more objective and repeatable method to help perform source classifications. In this paper, we …