Search Publications
X-Ray and Ultraviolet Observations of the Eclipsing Binary V471 Tauri with XMM-Newton: X-Ray-Cycles, Eclipse Timings and Further Evidence of a Substellar Tertiary Companion
Guinan, Edward; Engle, Scott; Ribas, Ignasi +2 more
Few stars offer as much toward understanding fundamental aspects of stellar astrophysics and binary star evolution than the eclipsing binary V471 Tauri (DAZ+K2V; P = 12.52 hr). V471 Tauri (Tau) is the product of common-envelope binary evolution and a pre-cataclysmic variable. X-ray and UV (291 nm) observations were secured with XMM-Newton over ~ 6…
Potential Habitability as a Stellar Property: Effects of Model Uncertainties and Measurement Precision
Tuchow, Noah W.; Wright, Jason T.
Knowledge of a star's evolutionary history combined with estimates of planet occurrence rates allows one to infer whether a star would be a good target in a search for biosignatures, and to quantify this intuition using long-term habitability metrics. In this study, we analyze the sensitivity of the biosignature yield metrics formulated by Tuchow …
Variability of L261 in M13
Violat-Bordonau, F.
After the discovery in April 2021 of the variability of the star L199 (now V63), belonging to the globular cluster Messier 13 (NGC 6205), between June and October 2021, we have studied twenty of the brightest stars, excluding the well-known red giant variables: surprisingly a good part of them shows some degree of variability in the range 0.05-0.2…
Toward measuring the spin of obscured supermassive black holes. A critical assessment with disk megamasers
Celotti, Annalisa; Masini, Alberto; Campitiello, Samuele
Context. Mass and spin are two fundamental properties of astrophysical black holes. While some established indirect methods are adopted to measure both these properties of active galactic nuclei (AGN) when viewed relatively face-on, very few suggested methods exist to measure these properties when AGN are highly inclined and potentially obscured b…
Acoustic waves in the Jovian dusty magnetosphere: a brief review and meta-analysis
Das, Souvik; Atteya, Ahmed; Karmakar, Pralay Kumar
The omnipresence of dust particulates in space and astrophysical plasmas has been attracting numerous researchers to study the collective excitation and propagation dynamics of different eigen-mode structures in diversified astrocosmic circumstances for years. It includes planetary rings, interplanetary space, cometary tails, asteroid zones, plane…
The Variability Behavior of NGC 925 ULX-3
Middleton, Matthew J.; Roberts, Timothy P.; Walton, Dominic J. +5 more
We report the results of a 2019-2021 monitoring campaign with Swift and associated target-of-opportunity observations with XMM-Newton and NuSTAR, examining the spectral and timing behavior of the highly variable ultraluminous X-ray source (ULX) NGC 925 ULX-3. We find that the source exhibits a 127-128-day periodicity, with fluxes typically ranging…
Kinematic Study of Radio-Loud CMEs Associated with Solar Flares and DH Type-II Radio Emissions During Solar Cycles 23 and 24
Pappa Kalaivani, P.; Prakash, O.; Shanmugaraju, A. +2 more
We have statistically analyzed 379 radio-loud (RL) CMEs and their associated flares during the period 1996 - 2019 covering both Solar Cycles (SC) 23 and 24. We classified them into two populations based on the observation period: i ) 235 events that belong to SC 23 (August 1996 - December 2008) and ii ) 144 events that belong to SC 24 (January 200…
Evaluating Helium Variations By Modeling Red Giant Branch Bump of Large Magellanic Cluster NGC 1978
Li, Cheng-Yuan; Ji, Xin; Deng, Li-Cai
Many evidences show that the Multiple Population (MP) features exist not only in old clusters but also in intermediate-age clusters in the Megallanic Clouds (MCs), which are characterized by star-to-star abundance scatter of several elements, including helium (He). The red giant branch bump (RGBB)'s photometric properties are proved to be related …
Optical microflares in LS I +61 303 and the search for their multiwavelength counterpart
Luque-Escamilla, Pedro L.; Martí, Josep; del Ser, Daniel +4 more
Context. Stellar sources of gamma rays are one of the front lines in modern astrophysics whose understanding can benefit from observational tools not originally designed for their study.
Aims: We take advantage of the high precision photometric capabilities of present-day space facilities to obtain a new perspective on the optical behavior of…
Compact and Variable Radio Emission from an Active Galaxy with Supersoft X-Ray Emission
Li, Di; Liu, Daizhong; Yang, Lei +15 more
RX J1301.9+2747 is a unique active galaxy with a supersoft X-ray spectrum that lacks significant emission at energies above 2 keV. In addition, it is one of few galaxies displaying quasiperiodic X-ray eruptions that recur on a timescale of 13-20 ks. We present multiepoch radio observations of RX J1301.9+2747 using GMRT, Very Large Array (VLA), and…