Zobrazeno 1 - 10
of 384
pro vyhledávání: '"Queiroz, A. B."'
Autor:
Khalatyan, A., Anders, F., Chiappini, C., Queiroz, A. B. A., Nepal, S., Ponte, M. dal, Jordi, C., Guiglion, G., Valentini, M., Elipe, G. Torralba, Steinmetz, M., Pantaleoni-González, M., Malhotra, S., Jiménez-Arranz, Ó., Enke, H., Casamiquela, L., Ardèvol, J.
We explore the feasibility of using machine-learning regression as a method of extracting basic stellar parameters and line-of-sight extinctions, given spectro-photometric data. To this end, we build a stable gradient-boosted random-forest regressor
Externí odkaz:
http://arxiv.org/abs/2407.06963
Autor:
Gallart, C., Surot, F., Cassisi, S., Fernández-Alvar, E., Mirabal, D., Rivero, A., Ruiz-Lara, T., Santos-Torres, J., Aznar-Menargues, G., Battaglia, G., Queiroz, A. B., Monelli, M., Vasiliev, E., Chiappini, C., Helmi, A., Hill, V., Massari, D., Thomas, G. F.
Publikováno v:
A&A 687, A168 (2024)
The current major challenge to reconstruct the chronology of the Milky Way (MW) is the difficulty to derive precise stellar ages. CMD-fitting offers an alternative to individual age determinations to derive the star formation history (SFH). We presen
Externí odkaz:
http://arxiv.org/abs/2402.09399
Autor:
Nepal, Samir, Chiappini, Cristina, Queiroz, Anna B. A., Guiglion, Guillaume, Montalbán, Josefina, Steinmetz, Matthias, Miglio, Andrea, Khalatyan, Arman
Publikováno v:
A&A 688, A167 (2024)
JWST has recently detected numerous disc galaxies at high-redshifts and there have been observations of cold disc galaxies at z > 4 with ALMA. In the Milky Way, recent studies find metal-poor stars in cold disc orbits, suggesting an ancient disc. We
Externí odkaz:
http://arxiv.org/abs/2402.00561
Autor:
Ardern-Arentsen, Anke, Monari, Giacomo, Queiroz, Anna B. A., Starkenburg, Else, Martin, Nicolas F., Chiappini, Cristina, Aguado, David S., Belokurov, Vasily, Carlberg, Ray, Monty, Stephanie, Myeong, GyuChul, Schultheis, Mathias, Sestito, Federico, Venn, Kim A., Vitali, Sara, Yuan, Zhen, Zhang, Hanyuan, Buder, Sven, Lewis, Geraint F., Oliver, William H., Wan, Zhen, Zucker, Daniel B.
The oldest stars in the Milky Way (born in the first few billion years) are expected to have a high density in the inner few kpc, spatially overlapping with the Galactic bulge. We use spectroscopic data from the Pristine Inner Galaxy Survey (PIGS) to
Externí odkaz:
http://arxiv.org/abs/2312.03847
We have already dealt with the problem of solving First Order Differential Equations (1ODEs) presenting elementary functions before in [1, 2]. In this present paper, we have established solid theoretical basis through a relation between the 1ODE we a
Externí odkaz:
http://arxiv.org/abs/2308.12391
Autor:
Kumar, Vipin, Rajpurohit, A. S., Srivastava, Mudit K., Fernández-Trincado, José G., Queiroz, A. B. A.
The time scales of variability in active M dwarfs can be related to their various physical parameters. Thus, it is important to understand such variability to decipher the physics of these objects. In this study, we have performed the low resolution
Externí odkaz:
http://arxiv.org/abs/2307.11574
Autor:
Ortigoza-Urdaneta, Mario, Vieira, Katherine, Fernández-Trincado, José G., Queiroz, Anna. B. A., Barbuy, Beatriz, Beers, Timothy C., Chiappini, Cristina, Anders, Friedrich, Minniti, Dante, Tang, Baitian
Publikováno v:
A&A 676, A140 (2023)
Based on high-quality APOGEE DR17 and Gaia DR3 data for 1,742 red giants stars within 5 kpc of the Sun and not rotating with the Galactic disc ($V_\phi <$ 100 km s$^{-1}$), we use the nonlinear technique of unsupervised analysis t-SNE to detect coher
Externí odkaz:
http://arxiv.org/abs/2306.08677
Autor:
Guiglion, G., Nepal, S., Chiappini, C., Khoperskov, S., Traven, G., Queiroz, A. B. A., Steinmetz, M., Valentini, M., Fournier, Y., Vallenari, A., Youakim, K., Bergemann, M., Mészáros, S., Lucatello, S., Sordo, R., Fabbro, S., Minchev, I., Tautvaišienė, G., Mikolaitis, Š., Montalbán, J.
In June 2022, Gaia DR3 has provided the astronomy community with about one million spectra from the Radial Velocity Spectrometer (RVS) covering the CaII triplet region. However, one-third of the published spectra have 15
Externí odkaz:
http://arxiv.org/abs/2306.05086
Autor:
Anders, F., Gispert, P., Ratcliffe, B., Chiappini, C., Minchev, I., Nepal, S., Queiroz, A. B. A., Amarante, J. A. S., Antoja, T., Casali, G., Casamiquela, L., Khalatyan, A., Miglio, A., Perottoni, H., Schultheis, M.
Publikováno v:
A&A 678, A158 (2023)
Over the last few years, many studies have found an empirical relationship between the abundance of a star and its age. Here we estimate spectroscopic stellar ages for 178 825 red-giant stars observed by the APOGEE survey with a median statistical un
Externí odkaz:
http://arxiv.org/abs/2304.08276
Autor:
Queiroz, Anna B. A., Anders, Friedrich, Chiappini, Cristina, Khalatyan, Arman, Santiago, Basilio X., Nepal, Samir, Steinmetz, Matthias, Gallart, Carme, Valentini, Marica, Ponte, Marina Dal, Barbuy, Beatriz, Pérez-Villegas, Angeles, Masseron, Thomas, Fernández-Trincado, José G., Khoperskov, Sergey, Minchev, Ivan, Fernández-Alvar, Emma, Lane, Richard R., Nitschelm, Christian
Publikováno v:
A&A 673, A155 (2023)
The Gaia mission has provided an invaluable wealth of astrometric data for more than a billion stars in our Galaxy. The synergy between Gaia astrometry, photometry, and spectroscopic surveys give us comprehensive information about the Milky Way. Usin
Externí odkaz:
http://arxiv.org/abs/2303.09926