Search Publications
Identification of new hot subdwarf binary systems by means of Virtual Observatory tools
Álvarez, M. A.; Dafonte, C.; Manteiga, M. +7 more
The estimation of the binary fraction of hot subdwarfs is key to shed light on the different evolution scenarios proposed to explain the loss of the hydrogen envelope during the red giant branch phase. In this paper, we analyse the spectral energy distribution of the hot subdwarfs included in a recent and comprehensive catalogue with the aim of id…
Machine learning for galactic archaeology: a chemistry-based neural network method for identification of accreted disc stars
Grand, Robert J. J.; Gómez, Facundo A.; Marinacci, Federico +4 more
We develop a method ('Galactic Archaeology Neural Network', GANN) based on neural network models (NNMs) to identify accreted stars in galactic discs by only their chemical fingerprint and age, using a suite of simulated galaxies from the Auriga Project. We train the network on the target galaxy's own local environment defined by the stellar halo a…
20 Orbits of binaries based on soar speckle observations
Docobo, José A.; Campo, Pedro P.; Mendez, Rene A. +3 more
New observational data obtained during the 2018, 2019, and 2020 speckle runs with the 4.1-m Southern Astrophysical Research (SOAR) telescope located at Cerro Pachón (Chile) allowed us to recalculate the orbits of the visual binaries: WDS 00277-1625 (YR 1 Aa,Ab), WDS 00462-2214 (RST4155), WDS 03124-4425 (JC 8), WDS 07427-3510 (HDS 1091), WDS 10093+…
A compact symmetric ejection from the low mass AGN in the LINER galaxy NGC 4293
Yang, Xiaolong; Wang, Ruiling; Guo, Quan
We conducted a Very Long Baseline Array (VLBA) observation of the low mass active galactic nucleus (AGN) in galaxy NGC 4293 (z = 0.003). The object is associated with a low-ionization nuclear emission-line region (LINER). Its black hole mass is estimated as ~105 or ${\sim}10^7 \, \mathrm{M}_\odot$. The VLBA 1.5 GHz image shows an invers…
A cosmological distance measure using radio-loud quasars
Huang, L.; Chang, Z. X.
We use the X-ray luminosity relation of radio-loud quasars (RLQs) to measure these luminosity distances as well as estimate cosmological parameters. We adopt four parametric models of X-ray luminosity to test luminosity correlation for RLQs and radio-intermediate quasars (RIQs) and give these cosmological distances. By Bayesian information criteri…
TIC 257060897b: An inflated, low-density, hot-Jupiter transiting a rapidly evolving subgiant star
Montalto, M.; Piotto, G.; Nascimbeni, V. +7 more
We report the discovery of a new transiting exoplanet orbiting the star TIC 257060897 and detected using TESS full frame images. We acquired HARPS-N time-series spectroscopic data, and ground-based photometric follow-up observations from which we confirm the planetary nature of the transiting body. For the host star we determined: Teff …
Near-infrared spectroscopy of extreme BAL QSOs from the QUBRICS bright quasar survey
Grazian, Andrea; Selvelli, Pierluigi; Boutsia, Konstantina +8 more
We report on the spectral confirmation of 18 quasi-stellar object (QSO) candidates from the QUasars as BRIght beacons for Cosmology in the Southern hemisphere (QUBRICS) survey, previously observed in the optical band, for which we acquired new spectroscopic data in the near-infrared band with the Folded-port InfraRed Echellette (FIRE) spectrograph…
Spectroscopic study of solar transition region oscillations in the quiet-Sun observed by IRIS using the Si IV spectral line
Srivastava, A. K.; Wang, T. J.; Kayshap, P. +3 more
In this paper, we use the Si IV 1393.755 Å spectral line observed by the Interface Region Imaging Spectrograph (IRIS) in the quiet-Sun (QS) to determine the physical nature of the solar transition region (TR) oscillations. We analyse the properties of these oscillations using wavelet tools (e.g. power, cross-power, coherence, and phase difference)…
The neutron-capture and α-elements abundance ratios scatter in old stellar populations: cosmological simulations of the stellar halo
Chiappini, Cristina; Cescutti, Gabriele; Scannapieco, Cecilia
We investigate the origin of the abundance ratios and scatter of the neutron-capture elements Sr, Ba, and Eu in the stellar halo of a Milky Way-mass galaxy formed in a hydrodynamical cosmological simulation, and compare them with those of α elements. For this, we implement a novel treatment for chemical enrichment of Type II supernovae that consid…
The recent star formation history of NGC 628 on resolved scales
Saintonge, Amélie; De Looze, Ilse; Decleir, Marjorie +1 more
Star formation histories (SFHs) are integral to our understanding of galaxy evolution. We can study recent SFHs by comparing the star formation rate (SFR) calculated using different tracers, as each probes a different time-scale. We aim to calibrate a proxy for the present-day rate of change in SFR, dSFR/dt, which does not require full spectral en…