Person:
Montes Gutiérrez, David

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First Name
David
Last Name
Montes Gutiérrez
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Física de la Tierra y Astrofísica
Area
Astronomía y Astrofísica
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Search Results

Now showing 1 - 10 of 15
  • Publication
    Li I enhancement during a long-duration stellar flare
    (EDP Sciencies, 1998-12) Montes Gutiérrez, David; Ramsey, Lawrence W.
    We report the possible detection of a Li I λ6708 Å line enhancement during an unusual long-duration optical flare in the recently discovered, X-ray/EUV selected, chromospherically active binary 2RE J0743+224. The Li I equivalent width (EW) variations follow the temporal evolution of the flare and large changes are observed in the intensity of the line. The maximum Li I enhancement (40% in EW) occurs just after the maximum chromospheric emission observed in the flare. A significant increase of the Li^-6/Li^-7 isotopic ratio is also detected. No significant simultaneous variations are detected in other photospheric lines. Neither line blends nor starspots seem to be the primary cause of the observed Li I line variation. From all this we suggest that this Li I enhancement is produced by spallation reactions during the flare.
  • 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
    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
    Optical and ultraviolet observations of a strong flare in the young, single K2 dwarf LQ Hya
    (Wiley, 1999-05-01) Montes Gutiérrez, David; Saar, S. H.; Collier Cameron, A.; Unruh, Y. C.
    We present high-resolution optical echelle spectra and IUE observations during a strong flare on 1993 December 22 in the very active, young, rapidly rotating, single K2 dwarf LQ Hya. The initial impulsive phase of the flare, which started sometime between 2:42 ut and 4:07 ut, was characterized by strong optical continuum enhancement and blueshifted emission lines with broad wings. The optical chromospheric lines reached their maximum intensity at ≈ 5:31 ut, by which time the blueshift vanished and the optical continuum enhancement had sharply decreased. Thereafter, the line emission slowly decreased and the lines redshift in a gradual phase that lasted at least two more hours. The Mg II lines behaved similarly. Quiescent C IV flux levels were not recovered until 21 h later, though a data gap and a possible second flare make the interpretation uncertain. In addition to the typically flare-enhanced emission lines (e.g., H α and H β), we observe He I D_3 going into emission, plus excess emission (after subtraction of the quiescent spectrum) in other He I and several strong neutral metal lines (e.g., Mg I b). Flare enhancement of the far-ultraviolet continuum generally agrees with an Si I recombination model. We estimate the total flare energy, and discuss the broad components, asymmetries and Doppler shifts seen in some of the emission lines.
  • Publication
    Library of medium-resolution Fiber Optic Echelle spectra of F, G, K, and M field dwarfs to giant stars
    (University Chicago Press, 1999-07) Montes Gutiérrez, David; Ramsey, Lawrence W.; Welty, Alan D.
    We present a library of Penn State Fiber Optic Echelle (FOE) observations of a sample of field stars with spectral types F to M and luminosity classes V to I. The spectral coverage is from 3800 to 10000 Å with a nominal resolving power of 12,000. These spectra include many of the spectral lines most widely used as optical and near-infrared indicators of chromospheric activity such as the Balmer lines (Hα to H epsilon), Ca II H & K, the Mg I b triplet, Na I D_1, D_2, He I D_3, and Ca II IRT lines. There are also a large number of photospheric lines, which can also be affected by chromospheric activity, and temperature-sensitive photospheric features such as TiO bands. The spectra have been compiled with the goal of providing a set of standards observed at medium resolution. We have extensively used such data for the study of active chromosphere stars by applying a spectral subtraction technique. However, the data set presented here can also be utilized in a wide variety of ways ranging from radial velocity templates to study of variable stars and stellar population synthesis. This library can also be used for spectral classification purposes and determination of atmospheric parameters (T_eff, log g, [Fe/H]). A digital version of all the fully reduced spectra is available via ftp and the World Wide Web (WWW) in FITS format.
  • 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.
  • Publication
    The Wilson-Bappu effect and other CA-II H-Line and K-line parameters relationships in chromospherically active binaries
    (EDP Sciencies, 1994-05) Montes Gutiérrez, David; Fernández Figueroa, María José; Castro Rubio, Elisa de; Cornide Castro-Piñeiro, Manuel
    We present measurements of the emission core width W_0 and the wavelength separation of the K_1 dips, W_1, of the Ca II H and K emission lines observed on high-dispersion spectra of 28 chromospherically active binary systems (RS CVn and BY Dra stars) and 18 single active stars. We test the width-luminosity correlations (the Wilson-Bappu (WB) effect, and (W_1, M_V) in these very active stars and analyse the influence of the activity level (I_K3) and the rotational broadening (Vsin i) in these correlations. We have found that for very active stars the emission widths, both W_0 and W_1, are larger than expected from previously accepted width-luminosity relations. The stars with strong emission intensities, I_K3 and large values of Vsin i seem to present larger values of W_0 than resulted from WB relation, the effect of the rotational velocity being the most remarkable. On the contrary, W_1 is strongly influenced by I_K3 but the effect of the rotational broadening is lesser. We also analyse the behaviour of the Ca II H and K line parameters in these very active stars in relation with less active stars and we found that the increase of W_1 and I_K1 With I_K3 presents a flattening for the most active stars which is different for each value of W_0. Finally we also find a Hepsilon width-luminosity correlation in the stars of the sample in which this emission line is present.
  • Publication
    Multiwavelength optical observations of chromospherically active binary systems - II. EZ Pegasi
    (EDP Sciencies, 1998-02-01) Montes Gutiérrez, David; Sanz Forcada, J.; Fernández Figueroa, María José; Castro Rubio, Elisa de; Poncet, A.
    The star EZ Peg, long ago classified as cataclysmic variable, has been shown to be a chromospherically active binary system of the RS CVn-type. In this paper we have analysed, using the spectral subtraction technique, simultaneous spectroscopic observations of the Hα, Hβ, Na I D_1 and D_2, He I D_3, Mg I b triplet, Ca II H & K, and Ca II infrared triplet lines. We have found that the hot component is the active star of the system, showing strong emission in the Hα, Ca Ir H & K, Hε, and Ca II IRT lines, and a strong filling-in of the Hβ line, however the Na I D_1 and D_2 and Mg I b triplet lines do not present filled-in. The He I D_3 could present a total filling-in due to microflaring. The observed variations (in different epochs and with the orbital phase) of the different activity indicators, formed at different height in the chromosphere, are correlated. Very broad wings have been found in the subtracted profiles of Hα and Ca II IRT λ8498 and λ8662 lines. These profiles are well matched using a two-component Gaussian fit (narrow and broad) and the broad component could be interpreted as arising from microflaring. The higher luminosity class of the hot component, that our spectra seem to indicate, could explain why the hot component is the active star of the system.