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 15
  • 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
    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.
  • Publication
    Multiwavelength optical observations of chromospherically active binary systems III: high resolution echelle spectra from Ca II H& K to Ca III RT
    (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 Hα profile of the very active star HU Vir. These profiles are well matched using a two-component Gaussian fit (narrow and broad) and the broad component can be interpreted as arising from microflaring. Red-shifted absorption features in the Hα 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 E_(Hα) / E_(Hβ) 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 D3 line has been detected as an absorption feature in mainly all the giants of the sample. Total filling-in of the He I D3, 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.
  • Publication
    Multiwavelength optical observations of chromospherically active binary systems - V. FF UMa (2RE J0933+624): a system with orbital period variation
    (EDP Sciencies, 2007-09) Gálvez, M. C.; Montes Gutiérrez, David; Fernández Figueroa, María José; Castro Rubio, Elisa de; Cornide Castro-Piñeiro, Manuel
    Context. This is the fifth paper in a series aimed at studying the chromospheres of active binary systems using several optical spectroscopic indicators to obtain or improve orbital solution and fundamental stellar parameters. Aims. We present here the study of FF UMa ( 2RE J0933+ 624), a recently discovered, X- ray/ EUV selected, active binary with strong Hα emission. The objectives of this work are, to find orbital solutions and define stellar parameters from precise radial velocities and carry out an extensive study of the optical indicators of chromospheric activity. Methods. We obtained high resolution echelle spectroscopic observations during five observing runs from 1998 to 2004. We found radial velocities by cross correlation with radial velocity standard stars to achieve the best orbital solution. We also measured rotational velocity by cross- correlation techniques and have studied the kinematic by galactic space- velocity components ( U, V, W) and Eggen criteria. Finally, we have determined the chromospheric contribution in optical spectroscopic indicators, from Ca II H & K to Ca II IRT lines, using the spectral subtraction technique. Results. We have found that this system presents an orbital period variation, higher than previously detected in other RS CVn systems. We determined an improved orbital solution, finding a circular orbit with a period of 3.274 days. We derived the stellar parameters, confirming the subgiant nature of the primary component (M_P = 1.67 M_[circled dot] and R sin i_P = 2.17 R_[circled dot]) and obtained rotational velocities (v sin i), of 33.57 +/- 0.45 km s^-1 and 32.38 +/- 0.75 km s^-1 for the primary and secondary components respectively. From our kinematic study, we can deduce its membership to the Castor moving group. Finally, the activity study has given us a better understanding of the possible mechanisms that produce the orbital period variation.
  • Publication
    Multiwavelength optical observations of the chromospherically active binary system MS Ser
    (Astronomical Society of the Pacific, 1999) Sanz Forcada, J.; Montes Gutiérrez, David; Fernández Figueroa, María José; Castro Rubio, Elisa de; Cornide Castro-Piñeiro, Manuel; Butler, C. J.; Doyle, J. G.
    We present here a continuation of our ongoing project of multiwavelength optical observations aimed at studying the chromosphere of active binary systems using the information provided for several optical spectroscopic features that are formed at different heights in the chromosphere. In this contribution we focus our study on the preliminary analysis of the active binary system MS Ser. We have taken Hα and Hβ spectra in 1995 and high resolution echelle spectra (covering Hα, Hβ, Na I D_1, D_2, He I D_3, Ca II H & K, and Ca II λ8662 lines) in 1998. Strong emission in the Ca II H & K and Ca III RT lines, coming from the primary component (recently classified as K2IV) is observed, and the secondary (G8V) also exhibits a small amount of emission. A near complete and variable filling-in of the Hα and Hβ is obtained after the application of the spectral subtraction technique. We detect also some seasonal variations between these two observing runs in comparison with our previous Ca II H & K observations taken in 1993.