Multi-wavelength observations of a giant flare on CN Leonis II. Chromospheric modelling with PHOENIX

被引:22
作者
Fuhrmeister, B. [1 ]
Schmitt, J. H. M. M. [1 ]
Hauschildt, P. H. [1 ]
机构
[1] Univ Hamburg, D-21029 Hamburg, Germany
关键词
stars: atmospheres; stars: late-type; stars: individual: CN Leonis; stars: chromospheres; stars: flare; RADIATIVE HYDRODYNAMIC MODELS; M-DWARFS; ULTRAVIOLET EMISSION; ATMOSPHERIC MODELS; STELLAR FLARES; SOLAR-FLARES; AD-LEONIS; LINE; SPECTRA; STARS;
D O I
10.1051/0004-6361/200810224
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Aims. In M dwarfs, optical emission lines and continua are sensitive to changing chromospheric conditions, e. g., during flares. To study flare conditions for an observed spectrum, a comparison to synthesised spectra from model atmospheres is needed. Methods. Using the stellar atmosphere code PHOENIX, we computed a set of 41 1D NLTE parameterised chromospheric models including the photosphere and parts of the transition region. By comparison of a linear combination of the synthesised spectra and a quiescent (observed) chromosphere to observed UVES/VLT spectra of a giant flare of the M 5.5 dwarf CN Leo (Gl406), we find the best-fitting flare model chromosphere. Results. Our model spectra give a fairly good overall description of the observed continua and emission lines. In the best-fitting model, the temperature minimum is deep in the atmosphere resulting in high electron pressure for the chromospheric flaring area. The inferred chromospheric filling factor of the flare is about 3 percent, which declines during the flare. The photospheric flare filling factor is about 0.3 percent.
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页数:9
相关论文
共 32 条
[21]  
LIEFKE C, 2010, A A UNPUB
[22]  
MAGAIN P, 1986, ASTRON ASTROPHYS, V163, P135
[23]  
MAUAS PJD, 1994, ASTRON ASTROPHYS, V281, P129
[24]  
Mauas PJD, 1996, ASTRON ASTROPHYS, V310, P245
[25]   THE WHITE-LIGHT FLARE OF 1982 JUNE 15 - OBSERVATIONS [J].
MAUAS, PJD .
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 1990, 74 (02) :609-646
[26]   MULTICHANNEL SPECTROPHOTOMETRY OF STELLAR FLARES [J].
MOCHNACKI, SW ;
ZIRIN, H .
ASTROPHYSICAL JOURNAL, 1980, 239 (01) :L27-L31
[27]   New algorithms for reducing cross-dispersed echelle spectra [J].
Piskunov, NE ;
Valenti, JA .
ASTRONOMY & ASTROPHYSICS, 2002, 385 (03) :1095-1106
[28]   THE PALOMAR MSU NEARBY-STAR SPECTROSCOPIC SURVEY .1. THE NORTHERN M-DWARFS - BANDSTRENGTHS AND KINEMATICS [J].
REID, IN ;
HAWLEY, SL ;
GIZIS, JE .
ASTRONOMICAL JOURNAL, 1995, 110 (04) :1838-1859
[29]   A coronal explosion on the flare star CN Leonis [J].
Schmitt, J. H. M. M. ;
Reale, F. ;
Liefke, C. ;
Wolter, U. ;
Fuhrmeister, B. ;
Reiners, A. ;
Peres, G. .
ASTRONOMY & ASTROPHYSICS, 2008, 481 (03) :799-805
[30]  
Short CI, 1997, ASTRON ASTROPHYS, V326, P287