Search Publications
On the Role of the Background Overlying Magnetic Field in Solar Eruptions
Wiegelmann, T.; Patsourakos, S.; Nindos, A.
The primary constraining force that inhibits global solar eruptions is provided by the overlying background magnetic field. Using magnetic field data from both the Helioseismic and Magnetic Imager aboard the Solar Dynamics Observatory and the spectropolarimeter of the Solar Optical Telescope aboard Hinode, we study the long-term evolution of the b…
Chemical and Kinematical Properties of Blue Straggler Stars and Horizontal Branch Stars in NGC 6397
Dalessandro, E.; Contreras Ramos, R.; Mucciarelli, A. +4 more
We used three sets of high-resolution spectra acquired with the multifiber facility FLAMES at the Very Large Telescope of the European Southern Observatory to investigate the chemical and kinematical properties of a sample of 42 horizontal branch (HB) stars, 18 blue straggler stars (BSSs), and 86 main-sequence (MS) turnoff (TO) and sub-giant branc…
CHEERS Results on Mrk 573: A Study of Deep Chandra Observations
Elvis, Martin; Karovska, Margarita; Fabbiano, Giuseppina +2 more
We present results on Mrk 573 obtained as part of the CHandra survey of Extended Emission-line Regions in nearby Seyfert galaxies (CHEERS). Previous studies showed that this source features a biconical emission in the soft X-ray band closely related to the narrow-line region as mapped by the [O III] emission line and the radio emission, though on …
The Absence of Ex-companions in Type Ia Supernova Remnants
Kilic, Mukremin; Di Stefano, R.
Type Ia supernovae (SNe Ia) play important roles in our study of the expansion and acceleration of the universe, but because we do not know the exact nature or natures of the progenitors, there is a systematic uncertainty that must be resolved if SNe Ia are to become more precise cosmic probes. No progenitor system has ever been identified either …
Orbital Decay and Evidence of Disk Formation in the X-Ray Binary Pulsar OAO 1657-415
Wilson-Hodge, C. A.; Camero-Arranz, A.; Finger, M. H. +1 more
OAO 1657-415 is an eclipsing X-ray binary wind-fed pulsar that has exhibited smooth spin-up/spin-down episodes and has undergone several torque reversals throughout its long history of observation. We present a frequency history spanning nearly 19 years of observations from the Burst and Transient Source Experiment and from the Gamma-Ray Burst Mon…
Active Learning to Overcome Sample Selection Bias: Application to Photometric Variable Star Classification
Miller, Adam A.; Bloom, Joshua S.; Richards, Joseph W. +6 more
Despite the great promise of machine-learning algorithms to classify and predict astrophysical parameters for the vast numbers of astrophysical sources and transients observed in large-scale surveys, the peculiarities of the training data often manifest as strongly biased predictions on the data of interest. Typically, training sets are derived fr…
Carbon-rich Dust Production in Metal-poor Galaxies in the Local Group
van Loon, J. Th.; Wood, P. R.; Zijlstra, A. A. +7 more
We have observed a sample of 19 carbon stars in the Sculptor, Carina, Fornax, and Leo I dwarf spheroidal galaxies with the Infrared Spectrograph on the Spitzer Space Telescope. The spectra show significant quantities of dust around the carbon stars in Sculptor, Fornax, and Leo I, but little in Carina. Previous comparisons of carbon stars with simi…
Thermal Properties of a Solar Coronal Cavity Observed with the X-Ray Telescope on Hinode
Reeves, Katharine K.; Gibson, Sarah E.; Kucera, Therese A. +2 more
Coronal cavities are voids in coronal emission often observed above high latitude filament channels. Sometimes, these cavities have areas of bright X-ray emission in their centers. In this study, we use data from the X-ray Telescope (XRT) on the Hinode satellite to examine the thermal emission properties of a cavity observed during 2008 July that …
SN 2010ay is a Luminous and Broad-lined Type Ic Supernova within a Low-metallicity Host Galaxy
Price, P. A.; Berger, E.; Cline, T. +38 more
We report on our serendipitous pre-discovery detection and follow-up observations of the broad-lined Type Ic supernova (SN Ic) 2010ay at z = 0.067 imaged by the Pan-STARRS1 3π survey just ~4 days after explosion. The supernova (SN) had a peak luminosity, MR ≈ -20.2 mag, significantly more luminous than known GRB-SNe and one of the most …
Numerical Simulations of the Magnetic Rayleigh-Taylor Instability in the Kippenhahn-Schlüter Prominence Model. II. Reconnection-triggered Downflows
Shibata, Kazunari; Isobe, Hiroaki; Hillier, Andrew +1 more
The launch of the Hinode satellite has allowed high-resolution observations of supersonic bright downflows in quiescent prominences, known as prominence knots. We present observations in the Ca II H spectral line using the Solar Optical Telescope on board the Hinode satellite of a descending plasma knot of size ~900 km. The knot initially undergoe…