Search Publications
Unraveling the Dusty Environment around RT Vir
Sargent, B.; Speck, Angela K.; Preston, Michael D. +1 more
Infrared (IR) studies of asymptotic giant branch (AGB) stars are critical to our understanding of the formation of cosmic dust. In this investigation, we explore the mid- to far-IR emission of the oxygen-rich AGB star RT Virginis. This optically thin dusty environment has unusual spectral features when compared to other stars in its class. To expl…
Deep high-resolution L band spectroscopy in the β Pictoris planetary system
Viswanath, Gayathri; Mollière, Paul; Janson, Markus +4 more
The β Pictoris system, with its two directly imaged planets β Pic b and β Pic c and its well characterised debris disk, is a prime target for detailed characterisation of young planetary systems. Here, we present high-resolution and high-contrast LM band spectroscopy with CRIRES+ of the system, primarily for the purpose of atmospheric characterisa…
Characterizing Superflares in HR 1099 Using Temporal and Spectral Analysis of XMM-Newton Observations
Srivastava, A. K.; Pandey, Jeewan C.; Didel, Shweta
In the present paper, we analyze three energetic X-ray flares from the active RS CVn binary HR 1099 using data obtained from XMM-Newton. The flare duration ranges from 2.8 to 4.1 hr, with e-folding rise and decay times in the range of 27–38 minutes and 1.3–2.4 hr, respectively, indicating rapid rise and slower decay phases. The flare frequency for…
A Bayesian Approach to Inferring Accretion Signatures in Young Stellar Objects: A Case Study with VIRUS
Mahadevan, Suvrath; Janowiecki, Steven; Zeimann, Gregory R. +3 more
The mass accretion rates of young stellar objects (YSOs) are key to understanding how stars form, how their circumstellar disks evolve, and even how planets form. We develop a Bayesian framework to determine the accretion rates of a sample of 15 YSOs using archival data from the VIRUS spectrograph (R ∼ 800, 3500–5500 Å) on the Hobby–Eberly Telesco…
The effects of measured slope on Martian lava flow modeling
Russo, Frances P.; Flynn, Ian T. W.; Peters, Sean I. +1 more
One of the most frequently used methods for modeling lava flows on Mars is commonly called the "standard rheologic approach" (SRA). This method requires measurements of the flow dimensions (e.g., width, length, thickness) and local topography (e.g., slope), which are used in equations of viscosity and yield strength, for example. Topography is a c…
Expansion-induced Three-part Morphology of the 2021 December 4 Coronal Mass Ejection
Wang, Yuming; Shen, Fang; Shen, Chenglong +9 more
The typical structure of a coronal mass ejection (CME) was identified as a three-part morphology, which includes a bright front, a dark cavity, and a bright core, with the cavity and the core generally regarded as flux rope and eruptive prominence. However, there are three-part CMEs that are not associated with prominences. In this work, we conduc…
Identifying Hierarchically Triple Star Systems with Gaia DR3 and LAMOST
Han, Zhanwen; Kovalev, Mikhail; Chen, Xuefei +8 more
Triple star systems are critical for understanding stellar dynamics and compact objects in astrophysics, yet confirmed hierarchical triples identified via spectroscopy remain limited. In this study, we identified 23 triple systems by cross matching the Gaia DR3 non-single-star catalog with Large Sky Area Multi-Object Fiber Spectroscopic Telescope …
Statistical Study of Electric Pc5 Pulsations in the Inner Magnetosphere Observed by Cluster
Li, Xinlin; Liu, Wenlong; Zhang, Dianjun +3 more
Ultra-low frequency (ULF) waves in the Pc5 band are essential for the transport of electrons in the radiation belt and the transport of energy from the solar wind into the magnetosphere. Based on ∼14-year of electric field data from Cluster satellite, the spatial distributions of power spectral densities (PSD) of electric field ULF waves in the in…
Orbital Inclination of Astrometric Binaries and the Dearth of Face-on Orbits in Gaia DR3 Solutions
Makarov, Valeri V.
The orbital solutions for astrometric (unresolved) binary stars provided in the Gaia mission DR3 reveal an obvious deficit of face-on orbits with line-of-sight inclinations close to 0 or π. This is shown to be an intrinsic mathematical feature of the orbit estimation technique involving the intermediate Thiele-Innes parameters, which are transform…
Swift-XRT and NuSTAR Monitoring of Obscuration Variability in Mrk 477
Ajello, M.; Marchesi, S.; Torres-Albà, N. +6 more
We present the analysis of 15 X-ray observations of Mrk 477, a nearby Seyfert 2 active galactic nucleus, with the objective to monitor its obscuring column density variability. The full data set consists of five archival observations, split into two XMM-Newton, two NuSTAR and one Chandra observation, plus two dedicated monitoring campaigns. The mo…