Search Publications
RXTE Observation of the Nonthermal Emission from the Early Stage Merger in A1750
Henriksen, Mark J.
We make the first observation-based calculation of the energy that goes into cosmic ray protons versus cosmic ray electrons in shock acceleration during structure formation. We find a ratio of energy in cosmic ray protons to energy in cosmic ray electrons of 0.86. This value, calculated from the nonthermal X-ray component reported here from RTXE a…
Erratum: "Identification of Faint Chandra X-Ray Sources in the Core-collapsed Globular Cluster NGC 6397: Evidence for a Bimodal Cataclysmic Variable Population" (2010, ApJ, 722, 20)
Anderson, Jay; Bogdanov, Slavko; Heinke, Craig O. +6 more
Near-infrared Spectroscopy of Ultracompact H II Regions in W51A with NIFS/ALTAIR
Damineli, Augusto; Navarete, Felipe; Conti, Peter S. +2 more
W51A is the most active star formation region of the giant H II region W51. It harbors the two massive protoclusters W51e and W51 IRS2, which are very rare in the Galaxy. We aim to identify the newborn massive stars and ultracompact H II regions to derive its distance and age. We performed Integral Field Unit observations with NIFS+ALTAIR of nine …
Infrared Line Emissions from Atoms and Atomic Ions in NGC 7027: Improved Wavelength Determinations for Infrared Metal Lines and a Probable Detection of Zn5+
Neufeld, David A.
An infrared L- and M-band spectral survey, performed toward the young planetary nebula NGC 7027 with the iSHELL instrument on NASA's Infrared Telescope Facility (IRTF), has revealed more than 20 vibrational lines of the molecules HeH+, H2, and CH+ and more than 50 spectral lines of atoms and atomic ions. The presen…
Near-infrared Polarization from Unresolved Disks around Brown Dwarfs and Young Stellar Objects
Espaillat, Catherine C.; Pillai, Thushara G. S.; Rilinger, Anneliese M. +1 more
Wide-field near-infrared (NIR) polarimetry was used to examine disk systems around two brown dwarfs (BDs) and two young stellar objects (YSOs) embedded in the Heiles Cloud 2 (HCl2) dark molecular cloud in Taurus as well as numerous stars located behind HCl2. Inclined disks exhibit intrinsic NIR polarization due to scattering of photospheric light,…
A Gap at 1 au in the Disk of DI Cha A Revealed by Infrared Interferometry
Pál, András; Moór, Attila; Ábrahám, Péter +6 more
DI Cha A is K0-type pre-main-sequence star, the brightest component of a quadruple stellar system. Here we report on a detailed study of this star based on archival VLTI/MIDI and VLTI/PIONIER infrared interferometric observations, as well as optical-infrared photometric monitoring from ground-based and space-born instruments. We determined the str…
X-Ray Spectra from Weakly Magnetized Accretion Flows
Pe'er, Asaf; Wallace, John
In this paper, we expand upon previous work that argued for the possibility of a subequipartition magnetic field in the accretion flow of a black hole binary system. Using X-ray observations of the three well-known sources A0620-00, XTE J1118+480, and V404 Cyg during the quiescent state, we compare the theoretically expected spectral shape with th…
Excitation and Excavation of the Claws of the Southern Crab
Frank, Adam; Balick, Bruce; Swegel, Ashley
We show that the Southern Crab (aka Hen2-104) presents an auspicious opportunity to study the form and speed of the invisible winds that excavate and shock the lobes of various types of bipolar nebulae associated with close and highly evolved binary stars. A deep three-color image overlay of Hen2-104 reveals that the ionization state of its lobe e…