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First detection and modelling of spatially resolved Lyα in TW Hya
Herczeg, Gregory J.; Bergin, Edwin A.; Gronke, Max +2 more
Lyman-α (Lyα) is the strongest emission line in the accretion-generated ultraviolet spectra from T Tauri stars and, as such, plays a critical role in regulating chemistry within the surrounding protoplanetary discs. Due to its resonant nature, the scattering of Lyα photons along the line of sight encodes information about the physical properties o…
Probing the Nature of Rotation in the Pleiades, Alpha Persei, and Hyades Clusters
Hao, C. J.; Xu, Y.; Hou, L. G. +5 more
Unraveling the internal kinematics of open clusters is crucial for understanding their formation and evolution. However, there is a dearth of research on this topic, primarily due to the lack of high-quality kinematic data. Using the exquisite-precision astrometric parameters and radial velocities provided by Gaia data release 3, we investigate th…
Towards a complete census of luminous Compton-thick active galactic nuclei in the Local Universe
Georgantopoulos, I.; Gandhi, P.; Akylas, A. +2 more
X-ray surveys provide the most efficient means for the detection of active galactic nuclei (AGNs). However, they do face difficulties in detecting the most heavily obscured Compton-thick AGNs. The BAT detector on board the Gehrels/Swift mission, operating in the very hard 14–195 keV band, has provided the largest samples of Compton-thick AGN in th…
Three new Galactic globular cluster candidates: FSR1700, Teutsch67, and CWNU4193
Minniti, D.; Alonso-García, J.; Gómez, M. +3 more
The VISTA Variables in the Via Láctea Extended Survey (VVVX) enables exploration of previously uncharted territories within the inner Milky Way (MW), particularly those obscured by stellar crowding and intense extinction. Our objective is to identify and investigate new star clusters to elucidate their intrinsic characteristics. Specifically, we a…
Discovery of a Proto–White Dwarf with a Massive Unseen Companion
Hermes, J. J.; Zakamska, Nadia L.; El-Badry, Kareem +8 more
We report the discovery of SDSS J022932.28+713002.7, a nascent extremely low-mass (ELM) white dwarf (WD) orbiting a massive (>1 M ⊙ at 2σ confidence) companion with a period of 36 hr. We use a combination of spectroscopy, including data from the ongoing fifth-generation Sloan Digital Sky Survey (SDSS-V), and photometry to measure the…
Using GMM in open cluster membership: An insight
Hasan, P.; Raja, M.; Hasan, S. N. +2 more
The unprecedented precision of Gaia has led to a paradigm shift in membership determination of open clusters where a variety of machine learning (ML) models can be employed. In this paper, we apply the unsupervised Gaussian Mixture Model (GMM) to a sample of thirteen clusters with varying ages (log t ≈ 6.38-9.64) and distances (441-5183 pc) from G…
The Clearing Timescale for Infrared-selected Star Clusters in M83 with HST
Calzetti, Daniela; Johnson, Kelsey E.; Sabbi, Elena +6 more
We present an analysis of Hubble Space Telescope data from Wide Field Camera 3 (WFC3)/Ultraviolet Imaging Spectrometer, WFC3/IR, and the Advanced Camera for Surveys, investigating the young stellar cluster (YSC) population in the face-on spiral galaxy M83. Within the field of view of the IR pointings, we identify 454 sources with compact F814W con…
Relative Yield of Thermal and Nonthermal Emission during Weak Flares Observed by STIX during 2021 September 20–25
Awasthi, Arun Kumar; Mrozek, Tomasz; Kołomański, Sylwester +3 more
The disparate nature of the thermal–nonthermal energy partition during flares, particularly during weak flares, is still an open issue. Following the Neupert effect, quantifying the relative yield of X-ray emission in different energy bands can enable the inferring of the underlying energy release mechanism. During 2021 September 20–25, the Solar …
The Proper Motion of the High Galactic Latitude Pulsar Calvera
Mereghetti, S.; Gotthelf, E. V.; Halpern, J. P. +2 more
Calvera (1RXS J141256.0+792204) is a pulsar of characteristic age 285 kyr at a high Galactic latitude of b = +37°, detected only in soft thermal X-rays. We measure a new and precise proper motion for Calvera using Chandra High Resolution Camera observations obtained 10 yr apart. We also derive a new phase-connected ephemeris using 6 yr of NICER da…
9 New Variable Stars in Exoplanetary Transit Fields Observed at the Caucasus Mountain Observatory
Tarasenkov, A.; Zubareva, A. M.; Maslennikova, N. +1 more