Search Publications
A Dynamical Model for Clustered Star Formation in the Galactic Disk
Conroy, Charlie; Ting, Yuan-Sen; Cargile, Phillip +3 more
The clustered nature of star formation should produce a high degree of structure in the combined phase and chemical space in the Galactic disk. To date, observed structure of this kind has been mostly limited to bound clusters and moving groups. In this paper, we present a new dynamical model of the Galactic disk that takes into account the cluste…
First Observations of Irregular Surface of Interplanetary Shocks at Ion Scales by Cluster
Kajdič, Primož; Blanco-Cano, Xóchitl; Burgess, David +2 more
We present the first observational evidence of the irregular surface of interplanetary (IP) shocks by using multispacecraft observations of the Cluster mission. In total we discuss observations of four IP shocks that exhibit moderate Alfvénic Mach numbers (M A ≤ 6.5). Three of them are high-β shocks with upstream β = 2.2-3.7. During the…
Characterization of a Sample of Southern M Dwarfs Using Harps and X-shooter Spectra
del Burgo, C.; Pavlenko, Ya. V.; Kuznetsov, M. K. +1 more
We present the homogeneous analysis of a sample of Southern early-type M dwarfs in the solar neighborhood (d < 60 pc). We used the MCAL technique to derive the effective temperature T eff, metallicity [Fe/H], and activity index i a (H alpha) of 420 M stars using HARPS spectra. The effective temperature T e…
Detection of Superluminal Motion in the X-Ray Jet of M87
Cheung, C. C.; Jones, Christine; Meyer, Eileen T. +5 more
Chandra HRC observations are investigated for evidence of proper motion and brightness changes in the X-ray jet of the nearby radio galaxy M87. Using images spanning 5 yr, proper motion is measured in the X-ray knot HST-1, with a superluminal apparent speed of 6.3 ± 0.4c, or 24.1 ± 1.6 mas yr-1, and in Knot D, with a speed of 2.4 ± 0.6c…
The Relation between Galaxy ISM and Circumgalactic O VI Gas Kinematics Derived from Observations and ΛCDM Simulations
Charlton, Jane C.; Kacprzak, Glenn G.; Churchill, Christopher W. +8 more
We present the first galaxy-O VI absorption kinematic study for 20 absorption systems (EW > 0.1 Å) associated with isolated galaxies (0.15 ≤ z ≤ 0.55) that have accurate redshifts and rotation curves obtained using Keck/ESI. Our sample is split into two azimuthal angle bins: major axis (Φ < 25°) and minor axis (Φ > 33°). O VI absorption a…
Hypervelocity Stars from a Supermassive Black Hole-Intermediate-mass Black Hole Binary
Tagawa, Hiromichi; Rossi, Elena Maria; Fragione, Giacomo +4 more
In this paper we consider a scenario in which the currently observed hypervelocity stars in our Galaxy have been ejected from the Galactic center as a result of dynamical interactions with an intermediate-mass black hole (IMBH) orbiting the central supermassive black hole (SMBH). By performing three-body scattering experiments, we calculate the di…
The Quintuplet Cluster: Extended Structure and Tidal Radius
Rui, Nicholas Z.; Hosek, Matthew W., Jr.; Lu, Jessica R. +4 more
The Quintuplet star cluster is one of only three known young (<10 Myr) massive (M > 104 M ⊙) clusters within ∼100 pc of the Galactic center (GC). In order to explore star cluster formation and evolution in this extreme environment, we analyze the Quintuplet’s dynamical structure. Using the HST WFC3-IR instrument, we tak…
Source Imaging of a Moving Type IV Solar Radio Burst and Its Role in Tracking Coronal Mass Ejection from the Inner to the Outer Corona
Chen, Yao; Feng, Shiwei; Vasanth, V. +5 more
Source imaging of solar radio bursts can be used to track energetic electrons and associated magnetic structures. Here we present a combined analysis of data at different wavelengths for an eruption associated with a moving type IV (t-IVm) radio burst. In the inner corona, the sources are correlated with a hot and twisted eruptive EUV structure, w…
The Dust and Molecular Gas in the Brightest Cluster Galaxy in MACS 1931.8-2635
Donahue, Megan; Frye, Brenda; Liu, Hauyu Baobab +6 more
We present new Atacama Large Millimeter Array observations of the molecular gas and far-infrared continuum around the brightest cluster galaxy (BCG) in the cool-core cluster MACS 1931.8-2635. Our observations reveal (1.9 ± 0.3) × 1010 M ⊙ of molecular gas, on par with the largest known reservoirs of cold gas in a cluster core…
An Ongoing Mid-infrared Outburst in the White Dwarf 0145+234: Catching in Action the Tidal Disruption of an Exoasteroid?
Ge, Jian; Wright, Edward L.; Bauer, James +7 more
We report the detection of a large-amplitude MIR outburst in the white dwarf (WD) 0145+234 in the NEOWISE Survey data. The source had a stable MIR flux before 2018, and was brightened by about 1.0 magnitude in the W1 and W2 bands within half a year and has been continuously brightening since then. No significant variations are found in the optical…