Search Publications
An Empirical Correlation of T max-M WD of Dwarf Novae and the Average White Dwarf Mass in Cataclysmic Variables in the Galactic Bulge
Li, Xiang-Dong; Bao, Tong; Xu, Xiao-jie +4 more
The mean white dwarf (WD) mass in the Galactic bulge cataclysmic variables (CVs) was measured by applying the shock temperature-WD mass correlation of magnetic cataclysmic variables (mCVs) to the Galactic bulge X-ray emission (GBXE) spectra. However, the resulting mean WD mass is lower than that of the local CVs. This discrepancy could be explaine…
Dissecting the X-Ray Emission in the Young Planetary Nebula NGC 7027
Kastner, Joel H.; Montez, Rodolfo, Jr.
We present an analysis of a second observation of the young planetary nebula (PN) NGC 7027 by the Chandra X-ray Observatory. This latest 59.2 ks exposure with ACIS-S was acquired approximately 14 years after the initial 18.2 ks ACIS-S observation, and the improved photon statistics allow us to perform a detailed spatial and spectral analysis of th…
Confirmation of a New Metal-poor Globular Cluster in the Galactic Bulge
Smith, Leigh C.; Minniti, Dante; Garofalo, Alessia +14 more
We use deep near-IR photometry of the VISTA Variables in the Vía Láctea (VVV) Survey and deep DECam Plane Survey (DECaPS) optical photometry to confirm the physical reality of the candidate globular cluster (GC) Minni 22, which is located in the Galactic bulge. This object, which was detected as a high density region in our maps of bulge red giant…
Direction-finding Analysis of the 2012 July 6 Type II Solar Radio Burst at Low Frequencies
Gopalswamy, Nat; Akiyama, Sachiko; Mäkelä, Pertti
The 2012 July 6 X1.1 flare at S13W59 and a halo coronal mass ejection (CME) with a space speed of ∼1900 km s-1 were associated with type III and type II radio bursts. The metric-to-decametric type II radio burst extended down to ∼5 MHz. Simultaneously, a slowly drifting feature with a harmonic structure was observed by Wind and Solar Te…
The Lyα Reference Sample. VIII. Characterizing Lyα Scattering in Nearby Galaxies
Cannon, John M.; Hayes, Matthew; Östlin, Göran +13 more
We examine the dust geometry and Lyα scattering in the galaxies of the Lyman Alpha Reference Sample (LARS), a set of 14 nearby (0.02< z< 0.2) Lyα-emitting and starbursting systems with Hubble Space Telescope Lyα, Hα, and Hβ imaging. We find that the global dust properties determined by line ratios are consistent with other studies, with some…
Update on the X-Ray Variability Plane for Active Galactic Nuclei: The Role of the Obscuration
González-Martín, Omaira
Scaling relations are the most powerful astrophysical tools to set constraints on the physical mechanisms of astronomical sources and to infer properties that cannot be accessed directly. We reinvestigate here one of these scaling relations in active galactic nuclei (AGNs); the so-called X-ray variability plane (or mass-luminosity timescale relati…
Late-time Observations of ASASSN-14lp Strengthen the Case for a Correlation between the Peak Luminosity of Type Ia Supernovae and the Shape of Their Late-time Light Curves
Zurek, David R.; Rest, Armin; Cara, Mihai +5 more
Late-time observations of Type Ia supernovae (SNe Ia), >900 days after explosion, have shown that this type of SN does not suffer an “IR catastrophe” at 500 days as previously predicted. Instead, several groups have observed a slow-down in the optical light curves of these SNe. A few reasons have been suggested for this slow-down, from a changi…
Period Analysis of Seven Field ab-type RR Lyrae Stars Based on O - C Diagrams: Cyclic Variations and Long-term Period Changes
Qian, S. -B.; Zhu, L. -Y.; Li, L. -J.
Using the times of light maximum collected from the GEOS RR Lyrae database and determined from sky surveys, we utilize the O - C method to study the period variations of seven field ab-type RR Lyrae stars. The time coverage of data for most stars is more than 100 years, allowing us to investigate period changes over a large time span. We find that…
Measurement Process and Inversions Using Helioseismic Normal-mode Coupling
Hanasoge, Shravan
Normal modes are coupled by the presence of perturbations in the Sun, providing a novel and underappreciated helioseismic technique with which to image the solar interior. The process of measuring coupling between normal modes is straightforward, much more so when compared with other prevalent helioseismic techniques. The theoretical framework to …
An Empirical Study of Contamination in Deep, Rapid, and Wide-field Optical Follow-up of Gravitational Wave Events
Berger, E.; Rest, A.; Foley, R. J. +10 more
We present an empirical study of contamination in wide-field optical follow-up searches of gravitational wave sources from Advanced LIGO/Virgo using dedicated observations with the Dark Energy Camera. Our search covered ∼56 deg2, with two visits per night, in the i and z bands, followed by an additional set of griz images three weeks la…