Search Publications
Infrared Excess of a Large OB Star Sample
Jiang, Biwei; Deng, Dingshan; Wang, Yuxi +2 more
The infrared (IR) excess from OB stars is commonly considered to be a contribution from ionized stellar wind or circumstellar dust. With the newly published Large Sky Area Multi-Object Fiber Spectroscopy Telescope (LAMOST)-OB catalog and Galactic O-Star Spectroscopic Survey data, this work steps further on understanding the IR excess of OB stars. …
Effects of Spectral Resolution on Simple Magnetic Field Diagnostics of the Mg II H and K Lines
Rempel, Matthias; Centeno, Rebecca; del Pino Alemán, Tanausú +1 more
We study the effects of finite spectral resolution on the magnetic field values retrieved through the weak-field approximation (WFA) from the cores of the Mg II h and k lines. The retrieval of the line-of-sight component of the magnetic field, B LOS, from synthetic spectra generated in a uniformly magnetized FAL-C atmosphere is accurate…
A Model-based Technique for Ad Hoc Correction of Instrumental Polarization in Solar Spectropolarimetry
Schad, Thomas A.; Tarr, Lucas A.; Jaeggli, Sarah A. +1 more
We present a new approach for correcting instrumental polarization by modeling the nondepolarizing effects of a complex series of optical elements to determine physically realizable Mueller matrices. Provided that the Mueller matrix of the optical system can be decomposed into a general elliptical diattenuator and general elliptical retarder, it i…
Gamma-Ray Orbital Modulation of the Transitioning Millisecond Pulsar Binary XSS J12270-4859
An, Hongjun
We report on gamma-ray orbital modulation of the transitioning MSP binary XSS J12270-4859 detected in the Fermi Large Area Telescope (LAT) data. We use long-term optical data taken with the XMM-Newton OM and the Swift UltraViolet Optical Telescope to inspect radio timing solutions that are limited to relatively short time intervals and find that e…
Simultaneous High Dynamic Range Algorithm, Testing, and Instrument Simulation
Chamberlin, Phillip C.; Jin, Meng; Woods, Thomas N. +4 more
Within an imaging instrument's field of view, there may be many observational targets of interest. Similarly, within a spectrograph's bandpass, there may be many emission lines of interest. The brightness of these targets and lines can be orders of magnitude different, which poses a challenge to instrument and mission design. A single exposure can…
LEGA-C: Analysis of Dynamical Masses from Ionized Gas and Stellar Kinematics at z 0.8
Bell, Eric F.; D'Eugenio, Francesco; Franx, Marijn +12 more
We compare dynamical mass estimates based on spatially extended stellar and ionized gas kinematics (M dyn,* and M dyn,eml, respectively) of 157 star-forming galaxies at 0.6 ≤ z < 1. Compared with z ~ 0, these galaxies have enhanced star formation rates, with stellar feedback likely affecting the dynamics of the gas. We us…
Comparison of Two Methods for Calculating Magnetic Helicity in the Solar Corona
Zhang, Mei; Yang, Shangbin; Yang, Xiao +1 more
Duo to the large magnetic Reynolds number, the magnetic helicity originating from the solar interior can be carried away through the photosphere into the corona. However, the relationship between the accumulated magnetic helicity flux through the photosphere and the magnetic helicity in the corona is still unclear. By selecting 36 newly emerging a…
Spectral Variability of the Born-again Ejecta in A 58
Toalá, Jesús A.; Guerrero, Martín A.; Rodríguez-González, Janis B. +1 more
Born-again planetary nebulae (PNs) allow investigating stellar evolution, dust production, and nebular shocks in human timescales. Here we present an analysis of multiepoch optical spectroscopic observations of the born-again PN A 58 around V605 Aql, which experienced a very late thermal pulse about a century ago. The H-deficient ejecta has experi…
X-Rays in Cepheids: Identifying Low-mass Companions of Intermediate-mass Stars
Drake, Jeremy J.; Evans, Nancy Remage; Breuval, Louise +12 more
X-ray observations have been made of a sample of 20 classical Cepheids, including two new observations (Polaris and l Car) reported here. The occurrence of X-ray flux around the pulsation cycle is discussed. Three Cepheids are detected (δ Cep, β Dor, and Polaris). X-rays have also been detected from the low-mass F, G, and K companions of four Ceph…
Evidence for a Dense, Inhomogeneous Circumstellar Medium in the Type Ia SNR 0519-69.0
Petre, Robert; Reynolds, Stephen P.; Ghavamian, Parviz +3 more
We perform an expansion study of the Balmer-dominated outer shock of the SNR 0519-69.0 in the LMC by using a combination of new Hubble Space Telescope (HST) WFC3 imagery obtained in 2020 and archival ACS images from 2010 and 2011. Thanks to the very long time baseline, our proper motion measurements are of unprecedented accuracy. We find a wide ra…