Search Publications
Zero-polarization candidate regions for the calibration of wide-field optical polarimeters
Blinov, D.; Panopoulou, G. V.; Readhead, A. C. S. +14 more
Context. The calibration of optical polarimeters relies on the use of stars with negligible polarization (i.e., unpolarized standard stars) for determining the instrumental polarization zero point. For wide-field polarimeters, calibration is often done by imaging the same star over multiple positions in the field of view (FoV), which is a time-con…
Probing the Stellar Populations and Star Formation History of Early-type Galaxies at 0 < z < 1.1 in the Rest-frame Ultraviolet
Desprez, Guillaume; Sawicki, Marcin; Gwyn, Stephen +6 more
We measure the evolution of the rest-frame near-ultraviolet (NUV)‑V colors for early-type galaxies in clusters at 0 < z < 1.1 using data from the Hyper Suprime-Cam Subaru Strategic Program, CFHT Large Area U-band Deep Survey, and local Sloan Digital Sky Survey clusters observed with Galaxy Evolution Explorer. Our results show that there is a…
Physical and geometrical properties of an Algol type eclipsing binary with a δ Scuti pulsator: HD 221072
Gürol, B.; Özdemir, S.; Gürsoytrak-Mutlay, S. H. +1 more
In this study, we obtained physical and geometrical parameters of an Algol type eclipsing binary hosting a δ Scuti pulsator. Based on the Transiting Exoplanet Survey Satellite (TESS) observations of HD 221072 system published in Sectors 24, 57, and 58, we obtained the photometric solution of the eclipsing binary. The light curve modelling reveals …
Energetic seed particles in self-consistent particle acceleration modeling at interplanetary shock waves
Vainio, R.; Vuorinen, L.; Trotta, D. +2 more
Aims. The study investigates the relevance of the seed particle population in the results of particle acceleration in interplanetary shock waves, when wave–particle interactions are treated self-consistently. Methods. We employed the SOLar Particle Acceleration in Coronal Shocks (SOLPACS) model, which is a proton acceleration simulation in shocks …
Correcting Projection Effects in CMEs Using GCS-Based Large Statistics of Multi-Viewpoint Observations
Morgan, Huw; Pal, Sanchita; Pant, Vaibhav +4 more
This study addresses the limitations of single-viewpoint observations of Coronal Mass Ejections (CMEs) by presenting results from a 3D catalog of 360 CMEs during solar cycle 24, fitted using the Graduated Cylindrical Shell (GCS) model. The data set combines 326 previously analyzed CMEs and 34 newly examined events, categorized by their source regi…
TESS Asteroseismology of β Hydri: A Subgiant with a Born-again Dynamo
Stassun, Keivan G.; Metcalfe, Travis S.; van Saders, Jennifer L. +12 more
The solar-type subgiant β Hyi has long been studied as an old analog of the Sun. Although the rotation period has never been measured directly, it was estimated to be near 27 days. As a Southern Hemisphere target, it was not monitored by long-term stellar activity surveys, but archival International Ultraviolet Explorer data revealed a 12 yr activ…
A catalogue of asteroseismically calibrated ages for APOGEE DR17. The predictions of a CatBoost machine learning model based on the [Mg/Ce] chemical clock and other stellar parameters
Boulet, Thibault
Context. The formation history and evolution of the Milky Way through cosmological time is a complex field of research requiring the sampling of highly accurate stellar ages for all Galaxy components. Such highly reliable ages are starting to become available thanks to the synergy of asteroseismology, spectroscopy, stellar modelling, and machine l…
The Milky Way Bulge Extra-tidal Star Survey: BH 261 (AL 3)
Clarkson, William I.; Kunder, Andrea; Johnson, Christian I. +19 more
The Milky Way Bulge extra-tidal star survey is a spectroscopic survey with the goal of identifying stripped globular cluster stars from inner Galaxy clusters. In this way, an indication of the fraction of metal-poor bulge stars that originated from globular clusters can be determined. We observed and analyzed stars in and around BH 261, an underst…
The mass distribution of stellar mergers: A new scenario for several FS CMa stars
Korčáková, D.; Kroupa, P.; Dvořáková, N. +1 more
Context. FS CMa stars belong to a diverse group of stars exhibiting the B[e] phenomenon, which manifests itself mainly by the presence of forbidden emission lines and a strong infrared (IR) excess in their spectra. Only a few tens of FS CMa stars are known and their nature is still unclear. Recently, a strong magnetic field has been discovered in …
Cygnus A obscuring torus: ionized, atomic, or molecular?
Ogle, Patrick; Antonucci, Robert; Bagul, Atharva +2 more
The prototypical powerful FR II radio galaxy Cygnus A fits extremely well into the quasar/radio galaxy unified model: high polarization with an angle almost perpendicular to the radio jet and polarized flux showing broad permitted lines. It has been claimed that ionized gas in the torus reveals a very clear torus shape via Bremmstrahlung emission.…