Person:
Fernández Figueroa, María José

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First Name
María José
Last Name
Fernández Figueroa
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Area
Astronomía y Astrofísica
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Now showing 1 - 10 of 22
  • Publication
    The nearest young moving groups
    (American Astronomical Society, 2006-06-01) López Santiago, Javier; Montes Gutiérrez, David; Crespo Chacón, I.; Fernández Figueroa, María José
    The latest results in the research of forming planetary systems have led several authors to compile a sample of candidates for searching for planets in the vicinity of the Sun. Young stellar associations are indeed excellent laboratories for this study, but some of them are not close enough to allow the detection of planets through adaptive optics techniques. However, the existence of very close young moving groups can solve this problem. Here we have compiled the members of the nearest young moving groups, as well as a list of new candidates from our catalog of late-type stars that are possible members of young stellar kinematic groups, studying their membership through spectroscopic and photometric criteria.
  • Publication
    Application of the spectral subtraction technique to the Ca II H & K and H_ε lines in a sample of chromospherically active binaries
    (EDP Sciences, 1995-12) Montes Gutiérrez, David; Castro Rubio, Elisa de; Fernández Figueroa, María José; Cornide Castro-Piñeiro, Manuel
    We present new spectroscopic observations in the Ca II H & K line region for a sample of 28 chromospherically active binary systems (RS CVn and BY Dra classes), with different activity levels. By using the spectral subtraction technique (subtraction of a synthesized stellar spectrum constructed from reference stars of similar spectral type and luminosity class) we obtain the active-chromosphere contribution to the Ca II H & K lines and to the H_ε line when it is present. We have compared the emission equivalent widths obtained with this technique with those obtained by reconstruction of the absorption line profile below the emission peak(s). The emissions arising from each individual star were obtained when it was possible to deblend the contribution of both components. The Ca II line profiles corresponding to different seasons and orbital phases are analysed in order to determine the contribution of each component and to study the chromospheric activity variations.
  • Publication
    A high-resolution spectroscopic survey of late-type stars: chromospheric activity, rotation, kinematics, and age
    (EDP Sciencies, 2010-05) López Santiago, Javier; Montes Gutiérrez, David; Gálvez Ortiz, M. C.; Crespo Chacón, I.; Martínez Arnáiz, R. M.; Fernández Figueroa, María José; Castro Rubio, Elisa de; Cornide Castro-Piñeiro, Manuel
    Aims. We present a compilation of spectroscopic data from a survey of 144 chromospherically active young stars in the solar neighborhood, which may be used to investigate different aspects of its formation and evolution in terms of kinematics and stellar formation history. The data have already been used by us in several studies. With this paper, we make all these data accessible to the scientific community for future studies on different topics. Methods. We performed spectroscopic observations with echelle spectrographs to cover the entirety of the optical spectral range simultaneously. Standard data reduction was performed with the IRAF echelle package. We applied the spectral subtraction technique to reveal chromospheric emission in the stars of the sample. The equivalent width of chromospheric emission lines was measured in the subtracted spectra and then converted to fluxes using equivalent width-flux relationships. Radial and rotational velocities were determined by the cross-correlation technique. Kinematics, equivalent widths of the lithium line lambda 6707.8 angstrom and spectral types were also determined. Results. A catalog of spectroscopic data is compiled: radial and rotational velocities, space motion, equivalent widths of optical chromospheric activity indicators from Ca II H & K to the calcium infrared triplet and the lithium line in lambda 6708 angstrom. Fluxes in the chromospheric emission lines and R(HK)' are also determined for each observation of a star in the sample. We used these data to investigate the emission levels of our stars. The study of the Ha emission line revealed two different populations of chromospheric emitters in the sample, clearly separated in the log F(H alpha)/F(bol) - (V - J) diagram. The dichotomy may be associated with the age of the stars.
  • Publication
    Late-type members of young stellar kinematic groups - I. Single stars
    (Wiley, 2001-11-21) Montes Gutiérrez, David; López Santiago, Javier; Gálvez, M. C.; Fernández Figueroa, María José; Castro Rubio, Elisa de; Cornide Castro-Piñeiro, Manuel
    This is the first paper of a series aimed at studying the properties of late-type members of young stellar kinematic groups. We concentrate our study on classical young moving groups such as the Local Association (Pleiades moving group, 20-150 Myr), IC 2391 supercluster (35 Myr), Ursa Major group (Sirius supercluster, 300 Myr), and Hyades supercluster (600 Myr), as well as on recently identified groups such as the Castor moving group (200 Myr). In this paper we compile a preliminary list of single late-type possible members of some of these young stellar kinematic groups. Stars are selected from previously established members of stellar kinematic groups based on photometric and kinematic properties as well as from candidates based on other criteria such as their level of chromospheric activity, rotation rate and lithium abundance. Precise measurements of proper motions and parallaxes taken from the Hipparcos Catalogue, as well as from the Tycho-2 Catalogue, and published radial velocity measurements are used to calculate the Galactic space motions (U, V W) and to apply Eggen's kinematic criteria in order to determine the membership of the selected stars to the different groups. Additional criteria using age-dating methods for late-type stars will be applied in forthcoming papers of this series. A further study of the list of stars compiled here could lead to a better understanding of the chromospheric activity and their age evolution, as well as of the star formation history in the solar neighbourhood. In addition, these stars are also potential search targets for direct imaging detection of substellar companions.
  • Publication
    The behaviour of the excess Ca II H and K and H_ε emissions in chromospherically active binaries
    (EDP Sciencies, 1996-08) Montes Gutiérrez, David; Fernández Figueroa, María José; Cornide Castro-Piñeiro, Manuel; Castro Rubio, Elisa de
    In this work we analyze the behaviour of the excess Ca II H and K and H_ ε emissions in a sample of 73 chromospherically active binary systems (RS CVn and BY Dra classes), of different activity levels and luminosity classes. This sample includes the 53 stars analyzed by Fernandez-Figueroa et al. (1994) and the observations of 28 systems described by Montes et al. (1995c). By using the spectral subtraction technique (subtraction of a synthesized stellar spectrum constructed from reference stars of spectral type and luminosity class similar to those of the binary star components) we obtain the active-chromosphere contribution to the Ca II H and K lines in these 73 systems. We have determined the excess Ca II H and K emission equivalent widths and converted them into surface fluxes. The emissions arising from each component were obtained when it was possible to deblend both contributions. We have found that the components of active binaries are generally stronger emitters than single active stars for a given effective temperature and rotation rate. A slight decline of the excess Ca II H and K emissions towards longer rotation periods, P-rot, and larger Rossby numbers, R_0, is found. When we use R_0 instead of P_rot, the scatter is reduced and a saturation at R_0≈0.3 is observed. A good correlation between the excess Ca II K and H_ ε chromospheric emission fluxes has been found. The correlations obtained between the excess Ca II K emission and other activity indicators, (C IV in the transition region, and X-rays in the corona) indicate that the exponents of the power-law relations increase with the formation temperature of the spectral features.
  • Publication
    Ca II H and K and H_α emissions in chromospherically active binary-systems (RS Canum Venaticorum and BY Draconis)
    (University Chicago Press, 1994-01) Fernández Figueroa, María José; Montes Gutiérrez, David; Castro Rubio, Elisa de; Cornide Castro-Piñeiro, Manuel
    We report high-resolution observations of the Ca II H and K and Balmer H_α lines in 53 chromospherically active binary systems including the RS Canum Venaticorum binaries (RS CVn) and BY Draconis (BY Dra) classes. The rotational periods of the sample cover a range from 0.8 to 83.2 days. H and K emission-line surface fluxes have been calculated for all the stars in the sample. In spectra where the H_ε line appears in emission, absolute surface fluxes were also determined. The Ca II line profiles corresponding to different seasons and orbital phases are analyzed in order to determine the contribution of each component and to study the chromospheric activity variations. We have measured the H_α equivalent width of the program stars and the H_α core emission was determined by subtraction of the equivalent width of a presumably inactive star of the same spectral type and luminosity class. Three different types of H_α line profiles have been found: strong emission line, weak emission line with strong superposed absorption profile, and filled-in absorption line profile.
  • Publication
    The behaviour of the excess Ca II H and K and H epsilon emissions in chromospherically active binaries
    (EDP Sciencies, 1996-08) Montes Gutiérrez, David; Fernández Figueroa, María José; Cornide Castro-Piñeiro, Manuel; Castro Rubio, Elisa de
    In this work we analyze the behaviour of the excess Ca II H & K and H emissions in a sample of 73 chromospherically active binary systems (RS CVn and BY Dra classes), of diferent activity levels and luminosity classes. This sample includes the 53 stars analyzed by Fernández-Figueroa et al. (1994) and the observations of 28 systems described by Montes et al. (1995c). By using the spectral subtraction technique (subtraction of a synthesized stellar spectrum constructed from reference stars of spectral type and luminosity class similar to those of the binary star components) we obtain the active chromosphere contribution to the Ca II H & K lines in these 73 systems. We have determined the excess Ca ii H & K emission equivalent widths and converted them into surface fluxes. The emissions arising from each component were obtained when it was possible to deblend both contributions. We have found that the components of active binaries are generally stronger emitters than single active stars for a given effective temperature and rotation rate. A slight decline of the excess Ca II H & K emissions towards longer rotation periods_(1) P_(rot1) and larger Rossby numbers, R_(01) is found. When we use R_(0) instead of P_(rot) the scatter is reduced and a saturation at R_(0)≈ 0.3 is observed. A good correlation between the excess Ca II K and He chromospheric emission fluxes has been found. The correlations obtained between the excess Ca II K emission and other activity indicators, (C IV in the transition region, and X-rays in the corona) indicate that the exponents of the power-law relations increase with the formation temperature of the spectral features.
  • Publication
    Late-type stars members of young stellar kinematic groups
    (Astronomical Society of the Pacific (ASP), 2000) Montes Gutiérrez, David; Latorre, A.; Fernández Figueroa, María José; Pallavicini, R.; Micela, G.; Sciortino, S.
    We have compiled a catalog of late-type stars (F5-M) members of representative, young disk, stellar kinematic groups: the Local Association (20-150 Myr), Ursa Mayor group (300 Myr), Hyades supercluster (600 Myr), IC 2391 supercluster (35 Myr), and Castor moving group (200 Myr). Stars have been selected from previously established members of stellar kinematic groups based in photometric and kinematic properties as well as from candidates based in other criteria as their level of chromospheric activity, rotation rate, lithium abundance. Precise measurements of proper motions and parallaxes taken from Hipparcos Catalogue, and published radial velocity measurements are used to calculate Galactic space motions (U, V, W) in order to determine the membership of the selected stars to the different stellar kinematic groups.
  • Publication
    Chromospheric activity, lithium and radial velocities of single late-type stars possible members of young moving groups
    (EDP Sciencies, 2001-12) Montes Gutiérrez, David; López Santiago, Javier; Fernández Figueroa, María José; Galves, M. C.
    We present here high resolution echelle spectra taken during three observing runs of 14 single late-type stars identified in our previous studies (Montes et al. 2001b, hereafter Paper I) as possible members of different young stellar kinematic groups (Local Association (20-150 Myr), Ursa Major group (300 Myr), Hyades supercluster (600 Myr), and IC 2391 supercluster (35 Myr)). Radial velocities have been determined by cross correlation with radial velocity standard stars and used together with precise measurements of proper motions and parallaxes taken from Hipparcos and Tycho-2 Catalogues, to calculate Galactic space motions (U, V, W) and to apply Eggen's kinematic criteria. The chromospheric activity level of these stars have been analysed using the information provided for several optical spectroscopic features (from the CaII H & K toCaII IRT lines) that are formed at different heights in the chromosphere. The Li I λ6707.8 Å line equivalent width (EW) has been determined and compared in the EW(Li I) versus spectral type diagram with the EW(Li I) of stars members of well-known young open clusters of different ages, in order to obtain an age estimation. All these data allow us to analyse in more detail the membership of these stars in the different young stellar kinematic groups. Using both, kinematic and spectroscopic criteria we have confirmed PW And, V368 Cep, V383 Lac, EP Eri, DX Leo, HD 77407, and EK Dra as members of the Local Association and V834 Tau, π^1 UMa, and GJ 503.2 as members of the Ursa Major group. A clear rotation-activity dependence has been found in these stars.
  • Publication
    Multiwavelength optical observations of chromospherically active binary systems III. High resolution echelle spectra from CaII H & K to CaII IRT
    (EDP Sciences, 2000-10) Montes Gutiérrez, David; Fernández Figueroa, María José; Castro Rubio, Elisa de; Cornide Castro-Piñeiro, Manuel; Latorre, A.; Sanz Forcada, J.
    This is the third paper of a series aimed at studying the chromosphere of active binary systems using the information provided for several optical spectroscopic features. High resolution echelle spectra including all the optical chromospheric activity indicators from the Ca II H & K to Ca II IRT lines are analysed here for 16 systems. The chromospheric contribution in these lines has been determined using the spectral subtraction technique. Very broad wings have been found in the subtracted H alpha profilp of the very active star HU Vir. These profiles are well matched using a two-component Gaussian fit; (narrow and broad) ard the broad component carl be interpreted as arising from microflaring. Red-shifted absorption features in the EHα line have been detected in several systems and excess emission in the blue wing of FG UMa was also detected. These features indicate that several dynamical processes, or a combination of them, may be involved. Using the EHα/EHβ ratio as a diagnostic we have detected prominence-like extended material viewed off the limb in many stars of the sample, and prominences viewed against the disk at some orbital phases in the dwarfs OU Gem and BF Lyn, The He I D_3 line has been detected as an absorption feature in mainly all the giants of the sample. Total filling-in of the He I D_3, probably due to microflaring activity, is observed in HU Vir. Self-absorption with red asymmetry is detected in the Ca II H & K lines of the giants 12 Cam: FG UMa and BM CVn. All the stars analysed show clear filled-in Ca II IRT lines or even notable emission reversal. The small values of the E_8542/E_8498 ratio we have found indicate Ca II IRT emission arises from plage-like regions. Orbital phase modulation of the chromospheric emission has been detected in some systems, in the case of HU Vir evidence of an active longitude area has been found.