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The STATiX pipeline for the detection of X-ray transients in three dimensions
Georgakakis, A.; Pierre, M.; Georgantopoulos, I. +3 more
The recent serendipitous discovery of a new population of short duration X-ray transients, thought to be associated with collisions of compact objects or stellar explosions in distant galaxies, has motivated efforts to build up statistical samples by mining X-ray telescope archives. Most searches to date, however, do not fully exploit recent devel…
A cautionary lesson from Gaia systematics: the mono-metallic globular cluster NGC 5904
Bianchini, Paolo; Mastrobuono-Battisti, Alessandra
The study of the chemistry of the stellar populations in globular clusters (GCs) is a fundamental task to unveil their formation in the high-redshift universe and to reconstruct the build-up of our Galaxy. Using metallicity estimates from BP/RP low-resolution Gaia DR3 spectra, a recent work presented the surprizing detection of two stellar populat…
Rotation and Hα Emission in a Young SMC Cluster: A Spectroscopic View of NGC 330
Dupree, Andrea K.; Milone, Antonino P.; Dotter, Aaron +4 more
We present an analysis of high-resolution optical spectra recorded for 30 stars of the split extended main-sequence turnoff of the young (∼40 Myr) Small Magellanic Cloud globular cluster NGC 330. Spectra were obtained with the Michigan/Magellan Fiber System and Magellan Inamori Kyocera Echelle spectrographs located on the Magellan-Clay 6.5 m teles…
Unequivocal detection of the tidal deformation of a red giant in a binary system via interferometry
Boffin, Henri M. J.; Merc, Jaroslav
While mass transfer in binary systems is a crucial aspect of binary evolution models, it remains far from understood. HD 352 is a spectroscopic binary exhibiting ellipsoidal variability, likely due to a tidally deformed giant donor filling its Roche lobe and transferring matter to a faint companion. Here, we analyze VLTI/PIONIER interferometric ob…
Discovery of three magnetic helium-rich hot subdwarfs with SALT
Dorsch, M.; Jeffery, C. S.; Woolf, V. M. +6 more
Magnetic fields with strengths ranging from 300 to 500 kG have recently been discovered in a group of four extremely similar helium-rich hot subdwarf (He-sdO) stars. In addition to their strong magnetic fields, these He-sdO stars are characterised by common atmospheric parameters, clustering around Teff = 46 500 K, a log ɡ/cm s‑1
Origin of the Chromospheric Umbral Waves in Sunspots
Xu, Zhe; Xue, Zhike; Yan, Xiaoli +5 more
Oscillations are ubiquitous in sunspots and the associated higher atmospheres. However, it is still unclear whether these oscillations are driven by the external acoustic waves (p-modes) or generated by the internal magnetoconvection. To obtain clues about the driving source of umbral waves in sunspots, we analyzed the spiral wave patterns (SWPs) …
Enhancing Exoplanet Ephemerides by Leveraging Professional and Citizen Science Data: A Test Case with WASP-77 A b
Dalba, Paul A.; Zellem, Robert T.; Evans, Phil +42 more
We present an updated ephemeris, and physical parameters, for the exoplanet WASP-77 A b. In this effort, we combine 64 ground- and space-based transit observations, 6 space-based eclipse observations, and 32 radial velocity observations to produce this target's most precise orbital solution to date aiding in the planning of James Webb Space Telesc…
Linear polarization study of open clusters in the anticenter direction: Signature of the spiral arms
Ganesh, Shashikiran; Joshi, Santosh; Uppal, Namita +2 more
Aims. Our objective is to investigate the distribution of dust and associated large-scale structures of the Galaxy using optical linear polarization measurements of various open clusters located at different distances in the Galactic anticenter direction. Methods. We present R-band linear polarization observations of stars toward five open cluster…
Tidal Disruption Event AT2020ocn: Early Time X-Ray Flares Caused by a Possible Disk Alignment Process
Jonker, P. G.; Zabludoff, A. I.; Pasham, D. R. +3 more
A tidal disruption event (TDE) may occur when a star is torn apart by the tidal force of a black hole (BH). Eventually, an accretion disk is thought to form out of stellar debris falling back toward the BH. If the star's orbital angular momentum vector prior to disruption is not aligned with the BH spin angular momentum vector, the disk will be ti…
Concurrent kink and sausage waves in a crescent-shaped structure over a limb prominence
Ghiasi, Maryam; Dadashi, Neda; Ebadi, Hossein
A Crescent-shaped prominence Structure (CS) over the solar west limb is studied using Extreme Ultra-Violet (EUV) Imaging Spectrometer/Hinode and Atmospheric Imaging Assembly (AIA)/Solar Dynamics Observatory (SDO). First, the time-varying positions of the top and bottom borders of the CS, along with its central axis, are derived. Time evolutions of…