Fernández Figueroa, María José

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First Name
María José
Last Name
Fernández Figueroa
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Astronomía y Astrofísica
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Now showing 1 - 6 of 6
  • Publication
    Hß photometry for uvby standard stars
    (IOP Publishing ltd, 1988-05) 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.
  • Publication
    Stellar activity in barium stars .1. Analysis of H-lines and K-lines CA-II-lines in 10 barium stars
    (IOP Publishing ltd, 1992-04) Cornide Castro-Piñeiro, Manuel; Fernández Figueroa, María José; Castro Rubio, Elisa de; Armentia, J. A.; Reglero, V.
    High dispersion spectra have been obtained in order to study the activity level of ten barium stars by means of the Ca II H and K emission flux, looking for a relation between barium intensity index and activity. Absolute magnitudes obtained from the Wilson-Bappu relationship disagree, in some cases, with the magnitudes computed from parallaxes, but this fact is not due to barium nature. Total emission fluxes, F(H + K) or R_HK index, plotted versus effective temperature show a distribution similar to that of cool giant stars. The asymmetry of K emission line, [F(K_2ν)/F(K_2r)], has been analyzed in relation with effective temperature, in this sense barium stars behave as expected of late-type giants with the only exception of two stars.
  • Publication
    Analysis of Ca II emission lines in seven RSCVn systems
    (EDP Sciencies, 1986-11) 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.
  • Publication
    Uvbyβ photometry of active-chromosphere binaries .1. The system TZ Coronae Borealis
    (IOP Publishing ltd, 1986-07) 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.
  • Publication
    The triple system HD 165590: a spectroscopic and photometric study
    (EDP Sciences, 1991-06) 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.
  • Publication
    A uvbyß survey of northern-hemisphere active binaries .2. The m_1 deficiency
    (EDP Sciencies, 1991-08) 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.