Search Publications
Unbound stars hold the key to young star cluster history
Pfalzner, Susanne; Arunima, Arunima; Govind, Amith
Aims.Gaia delivers the positions and velocities of stars at an unprecedented precision. Therefore, for star clusters, there exists much higher confidence in whether a specific star is a member of a particular cluster or not. However, membership determination is still especially challenging for young star clusters. At ages 2−10 Myr, the gas is expe…
TOI-1801 b: A temperate mini-Neptune around a young M0.5 dwarf
Nagel, E.; Amado, P. J.; Caballero, J. A. +79 more
We report the discovery, mass, and radius determination of TOI-1801 b, a temperate mini-Neptune around a young M dwarf. TOI-1801 b was observed in TESS sectors 22 and 49, and the alert that this was a TESS planet candidate with a period of 21.3 days went out in April 2020. However, ground-based follow-up observations, including seeing-limited phot…
Gaia Focused Product Release: Asteroid orbital solution. Properties and assessment
Prusti, T.; Mazeh, T.; Zucker, S. +403 more
Context. We report the exploitation of a sample of Solar System observations based on data from the third Gaia Data Release (Gaia DR3) of nearly 157 000 asteroids. It extends the epoch astrometric solution over the time coverage planned for the Gaia DR4, which is not expected before the end of 2025. This data set covers more than one full orbital …
Quiet-time suprathermal ions in the inner heliosphere during the rising phase of solar cycle 25
Wimmer-Schweingruber, R. F.; Allen, R. C.; Ho, G. C. +3 more
Context. The Solar Orbiter spacecraft made its first close perihelion passes in 2022, reaching 0.32 au on 26 March and 0.29 au on 12 October. Transient activity was relatively low, making it possible to perform measurements of the quiet-time suprathermal ion pool over multi-day periods.
Aims: The inner heliosphere suprathermal ion pool is a s…
Identifying preflare spectral features using explainable artificial intelligence
Kleint, Lucia; Panos, Brandon; Zbinden, Jonas
The prediction of solar flares is of practical and scientific interest; however, many machine learning methods used for this prediction task do not provide the physical explanations behind a model's performance. We made use of two recently developed explainable artificial intelligence techniques called gradient-weighted class activation mapping (G…
Quantitative spectroscopy of late O-type main-sequence stars with a hybrid non-LTE method
Butler, K.; Przybilla, N.; Aschenbrenner, P.
Context. Late O-type stars at luminosities log L/L⊙ ≲ 5.2 show weak winds with mass-loss rates lower than 10−8 M⊙ yr−1. This implies that, unlike their more massive and more luminous siblings, their photospheric layers are not strongly affected by the stellar wind.
Aims: A hybrid non-local thermodyn…
Evolution of dynamic fibrils from the cooler chromosphere to the hotter corona
Teriaca, Luca; Solanki, Sami K.; Long, David M. +17 more
Dynamic fibrils (DFs) are commonly observed chromospheric features in solar active regions. Recent observations from the Extreme Ultraviolet Imager (EUI) aboard the Solar Orbiter have revealed unambiguous signatures of DFs at the coronal base in extreme ultraviolet (EUV) emission. However, it remains unclear if the DFs detected in the EUV are link…
TOI-1736 and TOI-2141: Two systems including sub-Neptunes around solar analogs revealed by TESS and SOPHIE
Deleuil, M.; Moutou, C.; Winn, J. N. +32 more
Planetary systems around solar analogs inform us about how planets form and evolve in Solar System-like environments. We report the detection and characterization of two planetary systems around the solar analogs TOI-1736 and TOI-2141 using TESS photometry data and spectroscopic data obtained with the SOPHIE instrument on the 1.93 m telescope at t…
Benchmarking Gaia DR3 Apsis with the Hyades and Pleiades open clusters
Brandner, Wolfgang; Calissendorff, Per; Kopytova, Taisiya
Context. The Gaia astrophysical parameters inference system (Apsis) provides astrophysical parameter estimates for several to hundreds of millions of stars.
Aims: We aim to benchmark Gaia DR3 Apsis.
Methods: We compiled approximately 1500 bona fide single stars in the Hyades and Pleiades open clusters for validation of PARSEC isochrones,…
A neutron star candidate in the long-period binary 56 UMa
Jorissen, A.; Verschuur, G. L.; Schmelz, J. T. +6 more
Context. 56 UMa is a wide binary system that contains a chemically peculiar red giant and a faint companion. Due to its surface chemical abundances, the red giant was classified as a barium (Ba) star. This implies that the companion has to be a white dwarf, since Ba stars form when mass is transferred to them from an s-process rich Asymptotic Gian…