Search Publications
Freely Expanding Knots of X-Ray-emitting Ejecta in Kepler’s Supernova Remnant
Sato, Toshiki; Hughes, John P.
We report measurements of proper motion, radial velocity, and elemental composition for 14 compact X-ray-bright knots in Kepler’s supernova remnant (SNR) using archival Chandra data. The knots with the highest speed show both large proper motions (µ ∼ 0.″11-0.″14 yr-1) and high radial velocities (v ∼ 8700-10,020 km s-1)…
On the Statistical Properties of the Lower Main Sequence
Basu, Sarbani; Hekker, Saskia; Bellinger, Earl P. +1 more
Astronomy is in an era where all-sky surveys are mapping the Galaxy. The plethora of photometric, spectroscopic, asteroseismic, and astrometric data allows us to characterize the comprising stars in detail. Here we quantify to what extent precise stellar observations reveal information about the properties of a star, including properties that are …
High-energy Gamma-Ray Activity from V404 Cygni Detected by AGILE during the 2015 June Outburst
Verrecchia, F.; Tavani, M.; Piano, G. +2 more
The AGILE satellite detected transient high-energy γ-ray emission from the X-ray binary V404 Cygni, during the 2015 June outburst observed in radio, optical, X-ray, and soft γ-ray frequencies. The activity was observed by AGILE in the 50-400 MeV energy band, between 2015 June 24 UT 06:00:00 and 2015 June 26 UT 06:00:00 (MJD 57197.25-57199.25), wit…
The Optical Counterpart to the Accreting Millisecond X-Ray Pulsar SAX J1748.9-2021 in the Globular Cluster NGC 6440
Dalessandro, E.; Ferraro, F. R.; Lanzoni, B. +3 more
We used a combination of deep optical and {{H}}α images of the Galactic globular cluster NGC 6440, acquired with the Hubble Space Telescope, to identify the optical counterpart to the accreting millisecond X-ray pulsar SAX J1748.9-2021 during quiescence. A strong {{H}}α emission has been detected from a main-sequence star (hereafter COM-SAX J1748.…
Photoionization-driven Absorption-line Variability in Balmer Absorption Line Quasar LBQS 1206+1052
Wang, Jianguo; Zhou, Hongyan; Ji, Tuo +10 more
In this paper we present an analysis of absorption-line variability in mini-BAL quasar LBQS 1206+1052. The Sloan Digital Sky Survey spectrum demonstrates that the absorption troughs can be divided into two components of blueshift velocities of ∼700 and ∼1400 km s-1 relative to the quasar rest frame. The former component shows rare Balme…
XMM-Newton Observation of the nearby Pulsar B1133+16.
Haberl, Frank; Mitra, Dipanjan; Zhang, Bing +5 more
We constrain the X-ray properties of the nearby (360 {pc}), old (5 {Myr}) pulsar B1133+16 with ∼ 100 {ks} effective exposure time by XMM-Newton. The observed pulsar flux in the 0.2-3 keV energy range is ∼ {10}-14 {erg} {cm}}-2 {{{s}}}-1, which results in the recording of ∼600 source counts with the EPIC pn and MOS …
The Optical-Mid-infrared Extinction Law of the l = 165° Sightline in the Galactic Plane: Diversity of the Extinction Law in the Diffuse Interstellar Medium
Wang, Shu; de Grijs, Richard; Zhao, He +2 more
Understanding the effects of dust extinction is important to properly interpret observations. The optical total-to-selective extinction ratio, {R}V={A}V/E(B-V), is widely used to describe extinction variations in ultraviolet and optical bands. Since the {R}V=3.1 extinction curve adequately represents the average ex…
The Hard X-Ray Emission of the Blazar PKS 2155-304
Misra, R.; Dewangan, G. C.; Gaur, Haritma +4 more
The synchrotron peak of the X-ray bright High Energy Peaked Blazar PKS 2155-304 occurs in the UV-EUV region and hence its X-ray emission (0.6-10 keV) lies mostly in the falling part of the synchrotron hump. We aim to study the X-ray emission of PKS 2155-304 during different intensity states in 2009-2014 using the XMM-Newton satellite. We studied t…
Deep HST Imaging in 47 Tucanae: A Global Dynamical Model
Anderson, J.; Heyl, J.; Kalirai, J. +3 more
Multi-epoch observations with the Advanced Camera Survey and WFC3 on the Hubble Space Telescope provide a unique and comprehensive probe of stellar dynamics within 47 Tucanae. We confront analytic models of the globular cluster with the observed stellar proper motions that probe along the main sequence from just above 0.8-0.1M ⊙ as well…
The Class 0 Protostar BHR71: Herschel Observations and Dust Continuum Models
Dunham, Michael M.; Green, Joel D.; Yang, Yao-Lun +2 more
We use Herschel spectrophotometry of BHR71, an embedded Class 0 protostar, to provide new constraints on its physical properties. We detect 645 (non-unique) spectral lines among all spatial pixels. At least 61 different spectral lines originate from the central region. A CO rotational diagram analysis shows four excitation temperature components, …