Search Publications
Stellar Characterization and Radius Inflation of Hyades M-dwarf Stars from the APOGEE Survey
Pascucci, Ilaria; Bizyaev, Dmitry; Pan, Kaike +23 more
We present a spectroscopic analysis of a sample of 48 M-dwarf stars (0.2 M ⊙ < M < 0.6 M ⊙) from the Hyades open cluster using high-resolution H-band spectra from the Sloan Digital Sky Survey/Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. Our methodology adopts spectrum synthesis with LTE MARCS …
Irregular Proton Injection to High Energies at Interplanetary Shocks
Wimmer-Schweingruber, Robert F.; Dresing, Nina; Vainio, Rami +8 more
How thermal particles are accelerated to suprathermal energies is an unsolved issue, crucial for many astrophysical systems. We report novel observations of irregular, dispersive enhancements of the suprathermal particle population upstream of a high-Mach-number interplanetary shock. We interpret the observed behavior as irregular "injections" of …
The Early Light Curve of the Type Ia Supernova 2021hpr in NGC 3147: Progenitor Constraints with the Companion Interaction Model
Wheeler, J. Craig; Im, Myungshin; Kim, Dohyeong +19 more
The progenitor system of Type Ia supernovae (SNe Ia) is expected to be a close binary system consisting of a carbon/oxygen white dwarf (WD) and a nondegenerate star or another WD. Here, we present results from high-cadence monitoring observations of SN 2021hpr in a spiral galaxy, NGC 3147, and constraints on the progenitor system based on its earl…
The Polytropic Behavior of Solar Wind Protons as Observed by the Ulysses Spacecraft during Solar Minimum
Livadiotis, George; Nicolaou, Georgios; McComas, David J.
We analyze proton bulk parameters derived from Ulysses observations and investigate the polytropic behavior of solar wind protons over a wide range of heliocentric distances and latitudes. The large-scale variations of the proton density and temperature over heliocentric distance indicate that plasma protons are governed by subadiabatic processes …
A Gaia Data Release 3 View on the Tip of the Red Giant Branch Luminosity
Casertano, Stefano; Li, Siyang; Riess, Adam G.
The tip of the red giant branch (TRGB) is a standard candle that can be used to help refine the determination of the Hubble constant. Gaia Data Release 3 (DR3) provides synthetic photometry constructed from low-resolution BP/RP spectra for Milky Way field stars that can be used to directly calibrate the luminosity of the TRGB in the Johnson-Cousin…
New Velocity Measurements of NGC 5128 Globular Clusters Out to 130 kpc: Outer Halo Kinematics, Substructure, and Dynamics
Forbes, Duncan A.; Caldwell, Nelson; Strader, Jay +11 more
We present new radial velocity measurements from the Magellan and the Anglo-Australian Telescopes for 175 previously known and 121 newly confirmed globular clusters (GCs) around NGC 5128, the nearest accessible massive early-type galaxy at D = 3.8 Mpc. Remarkably, 28 of these newly confirmed GCs are at projected radii $\gt 50^{\prime} $ (≳54 kpc),…
A Recipe for Unbiased Background Modeling in Deep Wide-field Astronomical Images
van Dokkum, Pieter; Abraham, Roberto; Pasha, Imad +9 more
Unbiased sky background modeling is crucial for the analysis of deep wide-field images, but it remains a major challenge in low surface brightness astronomy. Traditional image processing algorithms are often designed to produce artificially flat backgrounds, erasing astrophysically meaningful structures. In this paper, we present three ideas that …
Crossing the Rubicon of Reionization with z 5 QSOs
Grazian, Andrea; Boutsia, Konstantina; Fiore, Fabrizio +12 more
One of the key open questions in cosmology is the nature of sources that completed cosmological hydrogen reionization at z ~ 5.2. High-z primeval galaxies have been long considered the main drivers of reionization, with a minor role played by high-z active galactic nuclei (AGN). However, in order to confirm this scenario, it is fundamental to meas…
Lack of Correlations between Cold Molecular Gas and AGN Properties in Type 1 AGNs at z ≲ 0.5
Ho, Luis C.; Bauer, Franz E.; Treister, Ezequiel +3 more
We present new NOrthern Extended Millimeter Array (NOEMA) observations of the CO(2-1) emission in eight of the brightest Palomar-Green quasars at z ≲ 0.5 to investigate the role of active galactic nucleus (AGN) feedback in luminous quasars detected at low redshifts. We detect CO(2-1) emission in three objects, from which we derive CO luminosities,…
A Multiwavelength Light-curve Analysis of the Classical Nova YZ Ret: An Extension of the Universal Decline Law to the Nebular Phase
Kato, Mariko; Hachisu, Izumi
YZ Ret is the first X-ray flash detected classical nova, and is also observed in optical, X-ray, and gamma-ray. We propose a comprehensive model that explains the observational properties. The white dwarf mass is determined to be ~1.33 M ☉, which reproduces the multiwavelength light curves of YZ Ret, from optical, X-ray, to gamma-ray. W…