Person:
Fernández Figueroa, María José

First Name

María José

Last Name

Fernández Figueroa

URI

https://hdl.handle.net/20.500.14352/83017

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Físicas

Area

Astronomía y Astrofísica

Identifiers

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Now showing 1 - 8 of 8

Uvbyβ photometry of active-chromosphere binaries .1. The system TZ Coronae Borealis
(Astronomical journal, 1986) Giménez, A.; Ballester, J. L.; Reglero, V.; Fernández Figueroa, María José; Castro Rubio, Elisa de
Simultaneous uvby and Hβ photometry of thee noneclipsing double-lined spectroscopic binary TZ CrB, an active binary system with almost unevolved components, is presented. A small amplitude distortion wave (0.012 mag in y) has been found with maximum light at phase ∽0.75. No variations in color or the βindex during the orbital cycle have been detected within the precision of the observations. The resulting color indices in the standard uvby system allow the estimation of some basic stellar parameters, such as the average effective temperature ∽6000 K and the stellar radii of the component stars ∽1.1 R_⨀. These results, together with available spectroscopic data, permit a consistent picture for this interesting binary to be obtained.
General properties of RS CVn systems
(Monthly notices of the Royal Astronomical Society, 1988) Montesinos, B.; Giménez, A.; Fernández Figueroa, María José
In this work we analyse the behaviour of 22 members of the RS CVn family whose absolute parameters are known by observation. We have carried out a study in comparison with detached and normal-evolution systems in order to obtain some general properties of this group of active binaries and test the evolutionary status. A comparison with evolutionary tracks of several metallicities and helium contents shows that there is a trend in these stars to have metal abundances equal to or larger than the solar one. The results are discussed in the light of the peculiar characteristics of this kind of binaries .
A uvbyβ survey of northern-hemisphere active binaries II: the m1 deficiency
(Astronomy & Astrophysics, 1991) Giménez, A.; Reglero, V.; De Castro, E.; Fernández Figueroa, María José
New photometric observations, using the uvby and Hβ systems of 72 northern-hemisphere active binaries are discussed in order to explain the main characteristics of their spectral light intensity distribution. Values of the parameter δm1 range from 0.0 to 0.3 mag, which cannot be explained in terms of metal underabundance alone. The existence of some mechanism, responsible for such a colour-index anomaly, is thus suggested and is found to be in close relation with the involved degree of solar-type activity.
The triple system HD 165590: a spectroscopic and photometric study
(Astronomy & astrophysics supplement series, 1991) Reglero, V.; Fernández Figueroa, María José; Giménez, A.; Castro Rubio, Elisa de; Fabregat, J.; Cornide Castro-Piñeiro, Manuel; Armentia, J. E.
A detailed study of the system V772 Her = HD 165590 = ADS 11060 AB is presented. The three identified components are found to be late type stars close to the zero-age main sequence with high rotational velocities. Spectroscopic observations allowed a quantitative determination of stellar activity indicators for the two members of the close binary as well as for the visual companion. An estimation of the most relevant physical parameters has been derived from the colour indices of each of the components and the close system has been found to be an eclipsing binary. This additional source of information combined with published measures of radial velocities, provides the absolute dimensions of the component stars (1.1 and 0.6 solar masses, and 0.9 and 0.6 solar radii) which confirm that the system is very little evolved. Moreover, a distance of 32 +/- 4 parsecs has been found to V772 Her in good agreement with available trigonometric determinations. Finally, we have compared these results with evolutionary models for main sequence stars of solar chemical composition.
Analysis of Ca II emission lines in seven RSCVn systems
(Astronomy & Astrophysics, 1986) Fernández Figueroa, María José; Montesinos, B.; Castro Rubio, Elisa de; Rego Fernández, Manuel; Giménez, A.; Reglero, V.
We report here new Ca II H and K emission line fluxes and equivalent widths for seven RSCVn binary systems, observed at several orbital phases. All the stars show enhanced chromospheric activity. With information from available spectra, an in dividual study for each star has been done. Double emission has been found for some systems in which perhaps the hotter component could be the more active. We have tested spectroscopically the model of localized active regions for the prototype RSCVn.
Hβ photometry for UVBY standard stars
(Astronomical journal, 1988) Reglero, V.; Giménez, A.; Fabregat, J.; de Catro, E.; Fernández Figueroa, María José; De Castro, A.
From 1984 to 1986 the authors made several observational campaigns at Calar Alto and La Palma Observatories using the uvby and β photometric systems to monitor a selected sample of late-type variable stars. In this paper they present the β values for 38 uvby standard stars to contribute to the uvby-β calibration works on late-type stars. In the final discussion, the β computed values are plotted against the Stroemgren b-y, m_(1), and c_(1) indices.
Hß photometry for uvby standard stars
(Astronomical journal, 1988) Reglero, V.; Giménez, A.; Fabregat, J.; Castro Rubio, Elisa de; Fernández Figueroa, María José; Castro, A. de
From 1984 to 1986, we made several observational campaigns at Calar Alto and La Palma Observatories using the uvby and ß photometric systems to monitor a selected sample of late-type variable stars. In this paper we present the ß values for 38 uvby standard stars to contribute to the uvby-ß calibration works on late-type stars. In the final discussion, the ß computed values are plotted against the Strömgren b - y, m_1, and c_1 indices.
A uvbyß survey of northern-hemisphere active binaries .2. The m_1 deficiency
(Astronomy & Astrophysics, 1991) Giménez, A.; Reglero, V.; Castro Rubio, Elisa de; Fernández Figueroa, María José
New photometric observations, using the uvby and Hß systems of 72 northern-hemisphere active binaries are discussed in order to explain the main characteristics of their spectral light intensity distribution. Values of the parameter δm_1 range from 0.0 to 0.3 mag, which cannot be explained in terms of metal underabundance alone. The existence of some mechanism, responsible for such a colour-index anomaly, is thus suggested and is found to be in close relation with the involved degree of solar-type activity.