L. J. Corral

Universidad de Guadalajara

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A. Herrero

Universidad de La Laguna

S. G. Navarro

Universidad de Guadalajara

P. Eenens

Universidad de Guanajuato

M. García

Centro de Astrobiología

N. Castro

Leibniz Institute for Astrophysics Potsdam

H. M. Tovmassian

Glendale Community College

M. R. Villamariz

Instituto de Astrofísica de Canarias

G. Tovmassian

Universidad Autónoma de Baja California

Miguel Flores R.

Universidad de Guadalajara

M. A. Urbaneja

Universität Innsbruck

Cooperative Institutions

Universidad Nacional Autónoma de México

Instituto de Astrofísica de Canarias

National Institute of Astrophysics, Optics and Electronics

Max Planck Society

Consejo Superior de Investigaciones Científicas

Universidad Autónoma de Baja California

Universidad de La Laguna

Ensenada Institute of Technology

Université de Montréal

Trinity House

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Candidate LBVs in Local Group galaxies

Symposium - International Astronomical Union (2003)

L. J. Corral A. Herrero

We present the results of photometric searches for LBV candidates (LBVc) made in some Local Group galaxies. We found eight candidates in a southern region of M 33 with characteristics similar to Var B and Var C. In IC 10, a galaxy without any LBV or LBVc reported before, we found one candidate.

Local Group

10.1017/s0074180900211819

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Citations (2)

Search for forced oscillations in binaries. III. Improved elements and the detection of line-profile variability of the B4V + A6V: system AR Cassiopeiae

Astronomy and Astrophysics (1999)

D. E. Holmgren P. Hadrava P. Harmanec P. Eenens L. J. Corral

An analysis of a new and extensive set of spectroscopic observations of the early-type binary system AR Cas, based also on spectral disentangling, has led to the discovery of the spectrum of the secondary star and of line-profile variations of the B4V primary star. A revised spectroscopic orbit based on these and published data is presented. We also present new photometric data, which have allowed us to improve the solution of the light curve and demonstrate the presence of apsidal motion. Determination of the basic physical parameters of the binary has allowed us to conclude that the system combines the main-sequence primary with an A6V: secondary, possibly an Am star. The consistency of our model of AR Cas is documentated by a comparison of model atmosphere flux profiles with the profiles recovered from the spectral disentangling. Analysis of the He I 667.8 nm line indicates that line profile variability is present, and that these variations may be periodic.

Apsidal precession

Line (geometry)

Eclipse

Spectral Analysis

Primary (astronomy)

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Citations (3)

A spectroscopic study of subluminous stars in NGC 2264.

RMxAA (1994)

R. Mújica Carlos Chavarría L. J. Corral L. Neri

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In savvy pursuit of Local Group blue massive stars

arXiv (Cornell University) (2010)

M. García A. Herrero N. Castro L. J. Corral

The important role of metallicity on massive star evolution and the combination of multi-object spectrographs and 10m class telescopes, have lead to numerous systematic studies of massive stars in Local Group galaxies. While color based quests of blue massive stars are relatively successful, they must be confirmed with spectroscopy and usually lead to lists dominated by B-type modest-mass stars. We have developed a friends of friends code to find OB associations in Local Group galaxies, presented in Garcia et al. (2009). One of the key points of the method is the photometric criterion to choose candidate OB stars from the reddening-free Q parameter, that could be easily extended to include from GALEX to near-IR photometry. While not a new idea, one of our code's strong advantages is the automatic determination of evolutionary masses for the members, enabling a quick and more insightful choice of candidates for spectroscopy, and the identification of potential advanced evolutionary stages. We present our work on the very metal-poor irregular IC 1613 (Garcia et al. 2010). The association properties are not only a powerful aid towards finding the most interesting candidate massive stars, but also reveal the galaxy's structure and recent star formation history.

Local Group

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The Extreme Of-Supergiant HD 15570 (O4If + )

V. F. Polcaro R. Viotti L. Norci P. Eenens L. J. Corral

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Counting Publications in Astronomy

L. J. Corral J. Sánchez Alméida

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Stellar Spectra Models Classification and Parameter Estimation Using Machine Learning Algorithms

arXiv (Cornell University) (2021)

Miguel Flores R.L. J. Corral C. Fierro

The growth of sky surveys and the large amount of stellar spectra in the current databases, has generated the necessity of developing new methods to estimate atmospheric parameters, a fundamental task on stellar research. In this work we present a comparison of different machine learning algorithms, using for the classification of stellar synthetic spectra and the estimation of fundamental stellar parameters included T_eff(K), log(L/Lo), log g, M/Mo, and Vrot. For both tasks, we established a group of supervised learning models, and propose a database of measures with the same structure to train the algorithms. This data includes equivalent-width types measurements over noisy synthetic spectra in order to replicate the natural noise on a real observed spectrum. Different levels of signal to noise ratio are considered for this analysis.

Replicate

SIGNAL (programming language)

Noisy data

10.48550/arxiv.2105.07110

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Citations (5)

Jets in Symbiotic Stars: The R Aqr Case

Environmental science and engineering (2012)

S. G. Navarro L. J. Corral

Collimated light

10.1007/978-3-642-27723-8_10

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Long-term spectral variability of the O4If⁺ star HD 15570 in the open cluster IC 1805

Symposium - International Astronomical Union (2003)

V. F. Polcaro Roberto Viotti L. Norci Corinne Rossi P. Eenens

We present preliminary results concerning the O4If + star HD 15570. Of-type supergiants are believed to represent an evolved evolutionary stage of very high mass stars (M init > 40 M ⊙ ). Their low numbers and extreme peculiarity make each of these objects worth of continuous monitoring. HD 15570 dominates the very young open cluster IC 1805 and is thought to have had an initial mass ≥ 100 M ⊙ . Low-, intermediate- and high-resolution spectra were collected at the Loiano and San Pedro Mártir telescopes since 1992. The comparison of our high- and low-resolution spectra shows clear variability of a number of spectral features. It is worth noticing, that the variation of Hα seems to follow a repeated secular trend, increasing its equivalent width from ~ 3Å to more than 8 Å in a few years. At the same time, its profile is varying, from a shape quite similar to the theoretical one corresponding to the Klein & Castor (1978) model C, to a much more developed P-Cygni profile, with a deep blue absorption wing. The possibility of instrumental effects is ruled out by the remarkable constancy of the nearby diffuse interstellar band at 6613 Å and of the He ii 6683 Å absorption. The Hβ profile variability is evident from the comparison of the 1996 and 1998 high-resolution spectra. The emission component, which is clearly visible at all epochs, is absent in the 1996 spectrum when the line appears in pure absorption. No relevant line-profile variation seems to be present in the He ii and N iii lines contributing to the ‘feature f’, that looks remarkably constant, as well as Hγ, while their equivalent widths seem to show a modest amount of random variability.

Star (game theory)

Equivalent width

Line (geometry)

10.1017/s0074180900212138

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Projected Rotational Velocities in Galactic OB Stars of Different OB Associations

Symposium - International Astronomical Union (2004)

L. J. Corral A. Herrero M. R. Villamariz

As a first step to study the influence that rotation has in the evolution of the most massive stars, we obtained the projected rotational velocity ( v sin i ) of a sample of OB stars from clusters and associations. We found that most of our stars present v sin i lower than 200 km/s.

10.1017/s0074180900195154

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