Search Publications
Comparison of Solar Multifrequency Microwave Data with Other Solar Indices for Understanding Solar and Stellar Microwave Data
Namekata, Kosuke; Shimojo, Masumi; Watanabe, Kyoko +2 more
Thermal microwave emissions detected from stellar atmospheres contain information on stellar activity. However, even for the Sun, the relationship between multifrequency microwave data and other activity indices remains unclear. We investigated the relationships among the thermal microwave fluxes with 1, 2, 3.75, and 9.4 GHz, their circular polari…
Discovery of Radial Spectral Hardening in the Hot Bubble of Planetary Nebula BD+30°3639 with Median Energy Imaging
Montez, Rodolfo
We apply an imaging analysis technique to study the spatial distribution of the X-ray spectral hardness across the hot bubble of planetary nebula BD+30°3639. Hot bubble emission is typically photon starved, thus limiting the methods for spatial–spectral analysis; however, this technique uses the statistics of photon energies across the nebula to i…
Mass-transfer Outbursts Reborn: Modeling the Light Curve of the Dwarf Nova EX Draconis
Baptista, Raymundo; Schlindwein, Wagner
EX Draconis is an eclipsing dwarf nova that shows outbursts with moderate amplitude (≃2 mag) and a recurrence timescale of ≃20–30 days. Dwarf novae outbursts are explained in terms of either a thermal-viscous instability in the disc or an instability in the mass-transfer rate of the donor star (MTIM). We developed simulations of the response of ac…
Radio Signature of the Strong Compression between a Streamer and a Coronal Hole Boundary
Aguilar-Rodriguez, E.; Vourlidas, A.; Corona-Romero, P. +8 more
We present evidence of the first detection of the radio signature at metric wavelengths of the strong compression between a helmet streamer (HS) and the boundary of a coronal hole (CH) using radio observations from the Callisto MEXICO-LANCE and ALASKA-HAARP systems and white-light observations obtained by the STEREO-A/COR1-COR2 coronagraphs. The e…
A JWST MIRI MRS View of the η Tel Debris Disk and Its Brown Dwarf Companion
Law, David R.; Chen, Christine H.; Hines, Dean C. +12 more
We report JWST Mid-Infrared Instrument (MIRI) Medium Resolution Spectrograph (MRS) observations of the β Pic moving-group member, η Tel A, along with its brown dwarf binary companion, η Tel B. Following point-spread-function subtraction, we recover the spatially resolved flux from the debris disk around η Tel A, along with the position of the comp…
Spectropolarimetric Radio Imaging of Faint Gyrosynchrotron Emission from a CME: A Possible Indication of the Insufficiency of Homogeneous Models
Mondal, Surajit; Oberoi, Divya; Kansabanik, Devojyoti
The geo-effectiveness of coronal mass ejections (CMEs) is determined primarily by their magnetic fields. Modeling of gyrosynchrotron (GS) emission is a promising remote sensing technique to measure the CME magnetic field at coronal heights. However, faint GS emission from CME flux ropes is hard to detect in the presence of bright solar emission fr…
WawHelioIonMP: A Semiempirical Tool for the Determination of Latitudinal Variation in the Ionization Rate of Interstellar Hydrogen and the Solar Wind
Bzowski, M.; Porowski, C.
The latitudinal structure of the solar wind varies during the cycle of solar activity. Analysis of this variation is important for understanding the solar activity and interpretation of observations of heliospheric energetic neutral hydrogen atoms and interstellar neutral (ISN) atoms inside the heliosphere, which yield information on the heliosphe…
Revealing the Elusive Companion of the Red Giant Binary 2MASS J05215658+4359220 from UV HST and Astrosat/UVIT Data
Hutchings, John; Thilker, David; Bianchi, Luciana +2 more
Black hole (BH) demographics in different environments is critical in view of recent results on massive star binarity, and of the multimessenger detectability of compact object mergers. But the identification and characterization of noninteracting BHs are elusive, especially in the sparse field stellar population. A candidate noninteractive BH + r…
Resolving Red Giant Winds with the Hubble Space Telescope
Harper, Graham M.; Wood, Brian E.; Müller, Hans-Reinhard
We describe recent spectroscopic observations of red giant stars made by the Space Telescope Imaging Spectrograph (STIS) instrument on board the Hubble Space Telescope, which has provided spatially resolved observations of the warm chromospheric winds that predominate for early K to mid-M giants. The H I Lyα lines of a set of 11 red giants observe…
JWST Resolves Collision-induced Absorption Features in White Dwarfs
Blouin, Simon; Dufour, Patrick; Kilic, Mukremin +2 more
Infrared-faint white dwarfs are cool white dwarfs exhibiting significant infrared flux deficits, most often attributed to collision-induced absorption (CIA) from H2–He in mixed hydrogen–helium atmospheres. We present James Webb Space Telescope (JWST) near- and mid-infrared spectra of three such objects using Near-Infrared Spectrograph (…