CF Tucanae: Another case of a coronal MAD syndrome?

被引:42
作者
Schmitt, JHMM
Stern, RA
Drake, JJ
Kurster, M
机构
[1] UNIV CALIF BERKELEY, CTR EUV ASTROPHYS, BERKELEY, CA 94720 USA
[2] LOCKHEED PALO ALTO RES LABS, SOLAR & ASTROPHYS LAB, PALO ALTO, CA 94304 USA
关键词
binaries; close; stars; coronae; individual (CF Tucanae); ultraviolet;
D O I
10.1086/177378
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present and discuss an extreme-ultraviolet spectrum of the RS CVn binary CF Tuc obtained with the short-wavelength (SW) spectrometer on board the Extreme-Ultraviolet Explorer (EUVE) satellite. In addition to a continuum, only two spectral lines attributed to Fe XXII and Fe XXIII are detected. We show that the EUVE data can be reconciled with a solar abundance plasma only if most of CF Tuc's emission measure is located at temperatures of approximate to 10(8) K; alternatively, the plasma must be iron depleted with most of the emission measure located at the peak. temperature of the observed line contribution functions. A comparison with previously obtained ROSAT PSPC spectra argues strongly in favor of the latter situation. As a consequence, we are forced to the conclusion that the iron abundance in the corona of CF Tuc is reduced with respect to solar values by factors between 5 and 10. The reasons for the occurrence of this metal abundance deficiency syndrome (MADS) are unclear at present; however, for the specific case of C-F Tuc, the extremely low coronal iron abundance might possibly result from an anomalously low photospheric iron abundance.
引用
收藏
页码:898 / 909
页数:12
相关论文
共 37 条
  • [1] ASCA OBSERVATIONS OF THE CORONAL X-RAY-EMISSION OF ALGOL
    ANTUNES, A
    NAGASE, F
    WHITE, NE
    [J]. ASTROPHYSICAL JOURNAL, 1994, 436 (01) : L83 - L86
  • [2] Bowyer S., 1991, EXTREME ULTRAVIOLET, P397
  • [3] NEW MODEL OF IRON SPECTRA IN THE EXTREME-ULTRAVIOLET AND APPLICATION TO SERTS AND EUVE OBSERVATIONS - A SOLAR ACTIVE-REGION AND CAPELLA
    BRICKHOUSE, NS
    RAYMOND, JC
    SMITH, BW
    [J]. ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 1995, 97 (02) : 551 - 570
  • [4] *CTR EUV ASTR, 1994, EUVE GO HDB
  • [5] STELLAR CORONAL ABUNDANCES .2. THE FIRST IONIZATION-POTENTIAL EFFECT AND ITS ABSENCE IN THE CORONA OF PROCYON
    DRAKE, JJ
    LAMING, JM
    WIDING, KG
    [J]. ASTROPHYSICAL JOURNAL, 1995, 443 (01) : 393 - 415
  • [6] DRAKE JJ, 1995, UNPUB APJ
  • [7] ASCA X-RAY-SPECTRA OF THE ACTIVE SINGLE STARS BETA-CETI AND PI(1)-URSAE-MAJORIS
    DRAKE, SA
    SINGH, KP
    WHITE, NE
    SIMON, T
    [J]. ASTROPHYSICAL JOURNAL, 1994, 436 (01) : L87 - L90
  • [8] THE EXTREME-ULTRAVIOLET SPECTRUM OF ALPHA AURIGAE (CAPELLA)
    DUPREE, AK
    BRICKHOUSE, NS
    DOSCHEK, GA
    GREEN, JC
    RAYMOND, JC
    [J]. ASTROPHYSICAL JOURNAL, 1993, 418 (01) : L41 - L44
  • [9] THE DISTRIBUTION OF NEUTRAL HYDROGEN IN THE INTERSTELLAR-MEDIUM .1. THE DATA
    FRUSCIONE, A
    HAWKINS, I
    JELINSKY, P
    WIERCIGROCH, A
    [J]. ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 1994, 94 (01) : 127 - 146
  • [10] AN ASCA OBSERVATION OF THE CASTOR SYSTEM
    GOTTHELF, EV
    JALOTA, L
    MUKAI, K
    WHITE, NE
    [J]. ASTROPHYSICAL JOURNAL, 1994, 436 (01) : L91 - L94