Search Publications
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…
HCN and HCO+ in Planetary Nebulae: The Next Level
Ziurys, L. M.; Schmidt, D. R.; Gold, K. R. +2 more
Observations of HCN and HCO+ have been carried out toward 13 planetary nebulae (PNe) using the facilities of the Arizona Radio Observatory (ARO). These nebulae represent a wide range of morphologies and ages (~2000-28,000 yr). For both molecules, the J = 1 → 0 transitions at 88-89 GHz and the J = 3 → 2 lines at 265-267 GHz were measured…
Pulse Timing Discovery of a Three-day Companion to the Hot Subdwarf BPM 36430
Hermes, J. J.; Barlow, Brad N.; Schaffenroth, Veronika +2 more
Hot subdwarf B stars are core-helium-burning objects that have undergone envelope stripping, likely by a binary companion. Using high-speed photometry from the Transiting Exoplanet Survey Satellite, we have discovered the hot subdwarf BPM 36430 is a hybrid sdBVrs pulsator exhibiting several low-amplitude g-modes and a strong p-mode puls…
An EUV Jet Driven by a Series of Transition Region Microjets
Fu, Hui; Xia, Lidong; Huang, Zhenghua +5 more
Jets are one of the most common eruptive events in the solar atmosphere, and they are believed to be important in the context of coronal heating and solar wind acceleration. We present an observational study on a sequence of jets with the data acquired with the Solar Dynamics Observatory and the Interface Region Imaging Spectrograph. This sequence…
The Ages of Optically Bright Subclusters in the Serpens Star-forming Region
Fang, Min; Herczeg, Gregory J.; Liu, Yao +2 more
The Serpens Molecular Cloud is one of the most active star-forming regions within 500 pc, with over 1000 young stellar objects (YSOs) at different evolutionary stages. The ages of the member stars inform us about the star formation history of the cloud. In this paper, we develop a spectral energy distribution (SED) fitting method for nearby evolve…
Optical Studies of 10 Hard X-Ray-selected Cataclysmic Binaries
Thorstensen, John R.; Halpern, Jules P.
We conducted time-resolved optical spectroscopy and/or photometry of 10 cataclysmic binaries that were discovered in hard X-ray surveys, with the goal of measuring their orbital periods and searching for evidence that they are magnetic. Four of the objects in this study are new optical identifications: IGR J18017-3542, PBC J1841.1+0138, IGR J18434…
Discrepancy between the Low-frequency Cutoffs of Type III Radio Bursts Based on Simultaneous Observations by WIND and PSP
Bale, Stuart D.; Pulupa, Marc; Wu, Dejin +2 more
The cutoff frequency is an important characteristic parameter of type III radio bursts. Employing the radio data of the Parker Solar Probe (PSP) in the encounter phases of its first five orbits, our previous work revealed that the maximum probability distribution of the cutoff frequency f lo (~680 kHz) is remarkably higher than that b…