Search Publications
A Method for the Estimation of f- and p-mode Parameters and Rotational Splitting Coefficients from Un-averaged Solar Oscillation Power Spectra
Kosovichev, A. G.; Scherrer, P. H.; Larson, T. P. +3 more
We present a new methodology for the fitting of the peaks in solar oscillation power spectra that is equally well-suited for the estimation of low-, medium, and high-degree f- and p-mode parameters and frequency-splitting coefficients. The method can provide accurate input data over a wide portion of the dispersion plane for both structural and ro…
Correlation of Structure and Stellar Properties of Galaxies in Stripe 82
Ho, Luis C.; Sachdeva, Sonali; Shankar, Francesco +1 more
Establishing a correlation (or lack thereof) between the bimodal color distribution of galaxies and their structural parameters is crucial to understand the origin of bimodality. To achieve that, we have performed a 2D mass-based structural decomposition (bulge+disk) of all disk galaxies (total = 1263) in the Herschel imaging area of the Stripe 82…
Optical Counterpart to the Ultraluminous X-Ray Source in the UGC 6456 Galaxy
Vinokurov, A.; Solovyeva, Y.; Atapin, K.
We report the identification of the optical counterpart to the transient ultraluminous X-ray source in the blue dwarf galaxy UGC 6456 (VII Zw 403). The source is highly variable in both the X-ray (by a factor of at least 100, 0.3-10 keV) and optical (by a factor of three, V-band) ranges. The peak X-ray luminosity of UGC 6456 ultraluminous X-ray so…
Variability of Massive Stars in M31 from the Palomar Transient Factory
Drout, Maria R.; Kulkarni, Shrinivas R.; Kupfer, Thomas +5 more
Using data from the (intermediate) Palomar Transient Factory (iPTF), we characterize the time variability of ≈500 massive stars in M31. Our sample is those stars that are spectrally typed by Massey and collaborators, including Luminous Blue Variables, Wolf-Rayets, and warm and cool supergiants. We use the high-cadence, long-baseline (≈5 yr) data f…
RGS Observations of Ejecta Knots in Tycho's Supernova Remnant
Katsuda, Satoru; Petre, Robert; Uchida, Hiroyuki +3 more
We present results from XMM-Newton/Reflection Grating Spectrometer (RGS) observations of prominent knots in the southernmost portion of Tycho's supernova remnant, known to be the remnant of a Type Ia supernova in 1572 C.E. By dispersing the photons from these knots out of the remnant with very little emission in front of or behind them, we obtaine…
Distance to the Energetic Neutral Hydrogen Source from the Heliotail
McComas, D. J.; Dayeh, M. A.; Sokół, J. M. +1 more
The interaction of the solar wind (SW) with the partially ionized interstellar medium forms the heliosphere. As the supersonic SW flows away from the Sun and incorporates pickup ions (PUIs), they are slowed, compressed, and heated at a termination shock, creating an energetic ion population in the inner heliosheath. The neutralization of PUIs in t…
NGC 7538 IRS1—an O Star Driving an Ionized Jet and Giant N-S Outflow
Wiesemeyer, Helmut; Güsten, Rolf; Sandell, Göran +4 more
NGC 7538 IRS 1 is a very young embedded O star driving an ionized jet and accreting mass with an accretion rate >10-4 ${M}_{\odot }$ yr-1, which is quenching the hypercompact H II region. We use SOFIA GREAT data, Herschel PACS and SPIRE archive data, SOFIA FORCAST archive data, Onsala 20 m and CARMA data, and JCMT archive …
Cosmological Evolution of Flat-spectrum Radio Quasars Based on the Swift/BAT 105 Month Catalog and Their Contribution to the Cosmic MeV Gamma-Ray Background Radiation
Fukazawa, Yasushi; Inoue, Yoshiyuki; Toda, Koyo
We present a new X-ray luminosity function of flat-spectrum radio quasars (FSRQs) utilizing the latest Swift/BAT 105 month X-ray source catalog. Contrary to previous studies of FSRQs in the X-ray band, using the luminosity-dependent density evolution model we find that FSRQs show evolutionary peaks at z ∼ 1-2 depending on luminosities. Our result …
Pointing Chandra toward the Extreme Ultraviolet Fluxes of Very Low Mass Stars
Drake, Jeremy J.; Kashyap, Vinay L.; Wolk, Scott J. +1 more
The X-ray and EUV emission of stars plays a key role in the loss and evolution of the atmospheres of their planets. The coronae of dwarf stars later than M6 appear to behave differently from those of earlier spectral types and are more X-ray dim and radio bright. Too faint to have been observed by the Extreme Ultraviolet Explorer, their EUV behavi…
Testing the Lamp-post and Wind Reverberation Models with XMM-Newton Observations of NGC 5506
Zoghbi, Abderahmen; Kalli, Sihem; Miller, Jon M. +1 more
The lamp-post geometry is often used to model X-ray data of accreting black holes. Despite its simple assumptions, it has proven to be powerful in inferring fundamental black hole properties such as the spin. Early results of X-ray reverberations showed support for such a simple picture, though wind reverberation models have also been shown to exp…