Search Publications
Magnetic Flux and Magnetic Nonpotentiality of Active Regions in Eruptive and Confined Solar Flares
Veronig, Astrid M.; Hou, Yijun; Li, Ting +3 more
With the aim of understanding how the magnetic properties of active regions (ARs) control the eruptive character of solar flares, we analyze 719 flares of Geostationary Operational Environmental Satellite (GOES) class ≥C5.0 during 2010-2019. We carry out the first statistical study that investigates the flare-coronal mass ejection (CME) associatio…
An ALMA Survey of Protoplanetary Disks in Lynds 1641
Fischer, William J.; Calvet, Nuria; Megeath, S. Thomas +8 more
We present ALMA observations of 101 protoplanetary disks within the star-forming region Lynds 1641 in the Orion Molecular Cloud A. Our observations include 1.33 mm continuum emission and spectral windows covering the J = 2-1 transition of 12CO, 13CO, and C18O. We detect 89 protoplanetary disks in the dust continuum…
Which Molecular Cloud Structures Are Bound?
Miville-Deschênes, Marc-Antoine; Heyer, Mark; Evans, Neal J., II +2 more
We analyze surveys of molecular cloud structures defined by tracers ranging from CO J = 1 → 0 through 13CO J = 1 → 0 to dust emission together with NH3 data. The mean value of the virial parameter and the fraction of mass in bound structures depends on the method used to identify structures. Generally, the virial parameter de…
Evidence for Ultra-diffuse Galaxy Formation through Tidal Heating of Normal Dwarfs
Sand, David J.; Jones, Michael G.; Zaritsky, Dennis +5 more
We have followed up two ultra-diffuse galaxies (UDGs), detected adjacent to stellar streams, with Hubble Space Telescope (HST) imaging and H I mapping with the Jansky Very Large Array in order to investigate the possibility that they might have a tidal origin. With the HST F814W and F555W images we measure the globular cluster (GC) counts for NGC …
The Second Discovery from the COCONUTS Program: A Cold Wide-orbit Exoplanet around a Young Field M Dwarf at 10.9 pc
Siverd, Robert J.; Claytor, Zachary R.; Dupuy, Trent J. +3 more
We present the identification of the second discovery from the COol Companions ON Ultrawide orbiTS (COCONUTS) program, the COCONUTS-2 system, composed of the M3 dwarf L 34-26 and the T9 dwarf WISEPA J075108.79-763449.6. Given their common proper motions and parallaxes, these two field objects constitute a physically bound pair with a projected sep…
Photometric Variability as a Proxy for Magnetic Activity and Its Dependence on Metallicity
Amard, Louis; See, Victor; Roquette, Julia +1 more
Understanding how the magnetic activity of low-mass stars depends on their fundamental parameters is an important goal of stellar astrophysics. Previous studies have shown that activity levels are largely determined by the stellar Rossby number, defined as the rotation period divided by the convective turnover time. However, we currently have litt…
An Improved Hertzsprung-Russell Diagram for the Orion Trapezium Cluster
Fang, Min; Pascucci, Ilaria; Apai, Dániel +1 more
We present a study of the Trapezium cluster in Orion. We analyze flux-calibrated Very Large Telescope/Multi-Unit Spectroscopic Explorer spectra of 361 stars to simultaneously measure the spectral types, reddening, and the optical veiling due to accretion. We find that the extinction law from Cardelli et al. with a total-to-selective extinction val…
The Effect of Stream Interaction Regions on ICME Structures Observed in Longitudinal Conjunction
Lugaz, Noé; Scolini, Camilla; Galvin, Antoinette B. +1 more
We study two interplanetary coronal mass ejections (ICMEs) observed at Mercury and at 1 au by spacecraft in longitudinal conjunction, investigating the question: what causes the drastic alterations observed in some ICMEs during propagation, while other ICMEs remain relatively unchanged? Of the two ICMEs, the first one propagated relatively self-si…
The IGRINS YSO Survey. I. Stellar Parameters of Pre-main-sequence Stars in Taurus-Auriga
Johns-Krull, Christopher M.; Hwang, Narae; Lee, Jae-Joon +19 more
We present fundamental parameters for 110 canonical K- and M-type (1.3-0.13 M⊙) Taurus-Auriga young stellar objects (YSOs). The analysis produces a simultaneous determination of effective temperature (Teff), surface gravity (log g), magnetic-field strength (B), and projected rotational velocity ( $v\sin i$ ). Our method emplo…
Age-dating Red Giant Stars Associated with Galactic Disk and Halo Substructures
Angus, Ruth; Huber, Daniel; Saunders, Nicholas +12 more
The vast majority of Milky Way stellar halo stars were likely accreted from a small number (≲3) of relatively large dwarf galaxy accretion events. However, the timing of these events is poorly constrained and predominantly relies on indirect dynamical mixing arguments or imprecise age measurements of stars associated with debris structures. Here, …