Search Publications
A Study of the 20 day Superorbital Modulation in the High-mass X-Ray Binary IGR J16493-4348
Fürst, Felix; Pottschmidt, Katja; Corbet, Robin H. D. +4 more
We report on Nuclear Spectroscopic Telescope Array (NuSTAR), Neil Gehrels Swift Observatory (Swift) X-ray Telescope (XRT), and Swift Burst Alert Telescope (BAT) observations of IGR J16493-4348, a wind-fed supergiant X-ray binary showing significant superorbital variability. From a discrete Fourier transform of the BAT light curve, we refine its su…
Hot Plasma in a Quiescent Solar Active Region as Measured by RHESSI, XRT, and AIA
Krucker, Säm; Ishikawa, Shin-nosuke
This paper investigates a quiescent (nonflaring) active region observed on 2010 July 13 in extreme ultraviolet (EUV), soft X-ray (SXR), and hard X-rays to search for a hot component that is speculated to be a key signature of coronal heating. We use a combination of Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) imaging and long-dur…
Diagnosing the Clumpy Protoplanetary Disk of the UXor Type Young Star GM Cephei
Neuhäuser, R.; Chen, W. P.; Mugrauer, M. +30 more
UX Orionis stars (UXors) are Herbig Ae/Be or T Tauri stars exhibiting sporadic occultation of stellar light by circumstellar dust. GM Cephei is such a UXor in the young (∼4 Myr) open cluster Trumpler 37, showing prominent infrared excess, emission-line spectra, and flare activity. Our photometric monitoring (2008-2018) detects (1) an ∼3.43 day per…
Auroral Beads at Saturn and the Driving Mechanism: Cassini Proximal Orbits
Roussos, E.; Badman, S. V.; Bonfond, B. +9 more
During the Grand Finale Phase of Cassini, the Ultraviolet Imaging Spectrograph on board the spacecraft detected repeated detached small-scale auroral structures. We describe these structures as auroral beads, a term introduced in the terrestrial aurora. Those on DOY 232 2017 are observed to extend over a large range of local times, i.e., from 20 L…
Eclipsing Binaries in the Open Cluster Ruprecht 147. II. Epic 219568666
Torres, Guillermo; Vanderburg, Andrew; Beichman, Charles A. +7 more
We report our spectroscopic monitoring of the detached, grazing, and slightly eccentric 12 day double-lined eclipsing binary EPIC 219568666 in the old nearby open cluster Ruprecht 147. This is the second eclipsing system to be analyzed in this cluster, following our earlier study of EPIC 219394517. Our analysis of the radial velocities combined wi…
Chandra, MDM, Swift, and NuSTAR Observations Confirming the SFXT Nature of AX J1949.8+2534
Halpern, Jules P.; Hare, Jeremy; Rahoui, Farid +3 more
AX J1949.8+2534 is a candidate supergiant fast X-ray transient (SFXT) observed in outburst by the International Gamma-ray Astrophysics Laboratory (IGR J19498+2534). We report on the results of six Neil Gehrels Swift-XRT, one Chandra, and one Nuclear Spectroscopic Telescope Array observation of the source. We find evidence of rapid X-ray variabilit…
Lyα Observations of High Radial Velocity Low-mass Stars Ross 1044 and Ross 825
Shkolnik, Evgenya L.; Schneider, Adam C.; Barman, Travis S. +1 more
The discovery of habitable zone (HZ) planets around low-mass stars has highlighted the need for a comprehensive understanding of the radiation environments in which such planets reside. Of particular importance is knowledge of the far-ultraviolet (FUV) radiation, as low-mass stars are typically much more active than solar-type stars and the proxim…
First Assessment of the Binary Lens OGLE-2015-BLG-0232
Bennett, D. P.; Soszyński, I.; Udalski, A. +54 more
We present an analysis of the microlensing event OGLE-2015-BLG-0232. This event is challenging to characterize for two reasons. First, the light curve is not well sampled during the caustic crossing due to the proximity of the full Moon impacting the photometry quality. Moreover, the source brightness is difficult to estimate because this event is…
Electron Densities and Nitrogen Abundances in Ionized Gas Derived Using [N II] Fine-structure and Hydrogen Recombination Lines
Lazio, T. Joseph W.; Horiuchi, Shinji; Goldsmith, Paul F. +7 more
We present a method for deriving the electron density of ionized gas using the ratio of the intensity of the [N II] 205 µm line to that of hydrogen radio recombination lines (RRLs). We use this method to derive electron densities of 21 velocity components in 11 lines of sight through the Galaxy, including the Galactic center. We observed, at…
Member Stars of the GD-1 Tidal Stream from the SDSS, LAMOST, and Gaia Surveys
Huang, Y.; Chen, B. -Q.; Wang, C. +5 more
With the photometric data from the SDSS survey, the spectroscopic data from the SDSS/SEGUE and the LAMOST surveys, and the astrometric data from the Gaia DR2, we have identified 67 highly probable member stars of the GD-1 cold stellar stream spread along almost its entire length (i.e., from 126° to 203° in R.A.). With the accurate spectroscopic (i…