Search Publications
Kelvin-Helmholtz Instabilities at the Sloshing Cold Fronts in the Virgo Cluster as a Measure for the Effective Intracluster Medium Viscosity
Churazov, E.; Forman, W. R.; Nulsen, P. E. J. +2 more
Sloshing cold fronts (CFs) arise from minor merger triggered gas sloshing. Their detailed structure depends on the properties of the intracluster medium (ICM): hydrodynamical simulations predict the CFs to be distorted by Kelvin-Helmholtz instabilities (KHIs), but aligned magnetic fields, viscosity, or thermal conduction can suppress the KHIs. Thu…
Transitional Disks and Their Origins: An Infrared Spectroscopic Survey of Orion A
Manoj, P.; Megeath, S. T.; Calvet, Nuria +10 more
Transitional disks are protoplanetary disks around young stars, with inner holes or gaps which are surrounded by optically thick outer, and often inner, disks. Here we present observations of 62 new transitional disks in the Orion A star-forming region. These were identified using the Spitzer Space Telescope's Infrared Spectrograph and followed up…
The Structural Evolution of Milky-Way-like Star-forming Galaxies since z ~ 1.3
van Dokkum, Pieter G.; Franx, Marijn; Muzzin, Adam +14 more
We follow the structural evolution of star-forming galaxies (SFGs) like the Milky Way by selecting progenitors to z ~ 1.3 based on the stellar mass growth inferred from the evolution of the star-forming sequence. We select our sample from the 3D-HST survey, which utilizes spectroscopy from the HST/WFC3 G141 near-IR grism and enables precise redshi…
Resolving the Optical Emission Lines of Lyα Blob "B1" at z = 2.38: Another Hidden Quasar
Villar-Martín, M.; Dijkstra, M.; Overzier, R. A. +5 more
We have used the SINFONI near-infrared integral field unit on the Very Large Telescope to resolve the optical emission line structure of one of the brightest (L Lyα ≈ 1044 erg s-1) and nearest (z ≈ 2.38) of all Lyα blobs (LABs). The target, known in the literature as object "B1", lies at a redshift where the main o…
Estimating the Arrival Time of Earth-directed Coronal Mass Ejections at in Situ Spacecraft Using COR and HI Observations from STEREO
Srivastava, Nandita; Mishra, Wageesh
Predicting the arrival time and transit speed of coronal mass ejections (CMEs) near the Earth is critical to understanding the solar-terrestrial relationship. Even though STEREO observations now provide multiple views of CMEs in the heliosphere, the true speeds derived from stereoscopic reconstruction of SECCHI coronagraph data are not quite suffi…
The Formation of the Massive Galaxies in the SSA22 z = 3.1 Protocluster
Lehmer, B. D.; Alexander, D. M.; Kubo, M. +15 more
We study the properties of K-band-selected galaxies (K AB < 24) in the z = 3.09 SSA22 protocluster field. 430 galaxies at 2.6 < z phot < 3.6 are selected as potential protocluster members in a 112 arcmin2 area based on their photometric redshifts. We find that ≈20% of the massive galaxies with stellar mass…
The Velocity Anisotropy of Distant Milky Way Halo Stars from Hubble Space Telescope Proper Motions
Brown, T. M.; Deason, A. J.; Guhathakurta, P. +2 more
Based on long baseline (5-7 years) multi-epoch HST/ACS photometry, used previously to measure the proper motion of M31, we present the proper motions (PMs) of 13 main-sequence Milky Way halo stars. The sample lies at an average distance of r ~= 24 kpc from the Galactic center, with a root-mean-square spread of 6 kpc. At this distance, the median P…
A Statistical Study of Transverse Oscillations in a Quiescent Prominence
Erdélyi, R.; Hillier, A.; Morton, R. J.
The launch of the Hinode satellite has allowed for seeing-free observations at high-resolution and high-cadence making it well suited to study the dynamics of quiescent prominences. In recent years it has become clear that quiescent prominences support small-amplitude transverse oscillations, however, sample sizes are usually too small for general…
The Density of Mid-sized Kuiper Belt Object 2002 UX25 and the Formation of the Dwarf Planets
Brown, M. E.
The formation of the largest objects in the Kuiper belt, with measured densities of ~1.5 g cm-3 and higher, from the coagulation of small bodies, with measured densities below 1 g cm-3, is difficult to explain without invoking significant porosity in the smallest objects. If such porosity does occur, measured densities should…
The Origin of Dust in Early-type Galaxies and Implications for Accretion onto Supermassive Black Holes
Storchi-Bergmann, Thaisa; Martini, Paul; Dicken, Daniel
We have conducted an archival Spitzer study of 38 early-type galaxies in order to determine the origin of the dust in approximately half of this population. Our sample galaxies generally have good wavelength coverage from 3.6 µm to 160 µm, as well as visible-wavelength Hubble Space Telescope (HST) images. We use the Spitzer data to est…