2009MNRAS.397.2133H


C.D.S. - SIMBAD4 rel 1.7 - 2019.12.14CET19:09:52

2009MNRAS.397.2133H - Mon. Not. R. Astron. Soc., 397, 2133-2147 (2009/August-3)

Observation and modelling of main-sequence star chromospheres - XII. Two-component model chromospheres for five active dM1e stars.

HOUDEBINE E.R.

Abstract (from CDS):

We aim to constrain the Hα, Caii H and Caii K profiles from quiescent and active regions on active dM1e stars.

A preliminary analysis of all the data available for dM1e stars shows that the Hα/Caii equivalent width (EW) ratio varies by up to a factor of 7 for different stars in our sample. We find that spectroscopic binaries have a significantly smaller ratio than single dM1e stars. We also find that the pre-main-sequence stars Gl 616.2, GJ 1264 and Gl 803 have a ratio lower than main-sequence single dM1e stars. These differences imply that different chromospheric structures are present on different stars, notably the temperature minimum must decrease with an increasing Hα/Caii EW ratio. For these reasons, it is impossible to reproduce all observations with only one grid of model chromospheres.

We show that the grid of model chromospheres of Paper VI is adequate to describe the physical conditions that prevail in the chromospheres of spectroscopic binaries and pre-main-sequence M1e stars, but not for the conditions in single dM1e stars. One or more additional grids of model chromospheres will be necessary to reproduce all observations.

We use the method developed in Paper XI in this series, in order to build two-component model chromospheres for five M1e field stars: FF And A, FF And B, GJ 1264, AU Mic and Gl 815A. Our solutions provide an exact match of the Hα and the mean Caii H & K EWs within measurement uncertainties. We compare the theoretical profiles and the observed profiles of Hα and the Caii H & K resonance lines. On the one hand, our fits to the Caii lines are reasonably good. On the other hand, our models tend to produce Hα profiles with a central absorption that is too deep. This suggests that the column mass at the transition region for plages is underestimated, but this would imply that the contrast factor between quiescent and active regions in the Caii lines is larger than 5.

We find that, except in the cases of FF And A and AU Mic, the total Hα profile is dominated by the contributions from plage regions. The Hα profiles in quiescent regions are typically filled in or slightly in emission. We also find that, as in the case of the less active dM1 stars, Caii emission in dM1e stars is generally dominated by the contribution from plage regions. We find plage filling factors typically in the range 10 to 60 per cent. These are on average (40 per cent) slightly larger than those derived for the less active dM1 stars (30 per cent).

Our modelling shows that the grid of model chromospheres of Paper VI is adequate for only a subset of dM1e stars. Physical conditions that prevail in the chromospheres of dM1e stars are very different from one star to another. For this reason, this study demonstrates the critical need for several improved grids of model chromospheres as well as higher signal-to-noise ratio data.


Abstract Copyright: © 2009 The Authors. Journal compilation © 2009 RAS

Journal keyword(s): line: formation - radiative transfer - stars: chromospheres - stars: emission-line, Be - stars: late-type

Simbad objects: 29

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Number of rows : 29

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 BD+44 4548 PM* 00 05 10.8891772602 +45 47 11.639549811   11.45   9.2   M2Ve 126 0
2 G 242-51 PM* 00 23 28.8272613426 +77 11 21.451816548   11.304   10.7   M2.5V 47 0
3 V* FF And BY* 00 42 48.2494872638 +35 32 55.658040363   11.84   9.941   M1Ve+M1Ve 138 0
4 BD+61 195 PM* 01 02 38.8679928575 +62 20 42.172837073   11.439   8.7   M1.5V 185 0
5 LP 356-14 A PM* 03 24 06.4798157313 +23 47 06.126281053   12.21 10.423 10.18   M1.5Ve 48 0
6 MCC 428 PM* 03 43 45.2472698195 +16 40 02.169395779 13.476 12.265 10.763 9.78 8.681 M0V 71 0
7 GJ 3305 TT* 04 37 37.4507041928 -02 29 28.869007822   12.04 10.59   8.59 M1.1V 103 0
8 V* V1005 Ori BY* 04 59 34.8341800543 +01 47 00.672080375   11.48 10.107 9.603 8.239 M0Ve 295 0
9 HD 36705 TT* 05 28 44.8916324761 -65 26 55.289846904 8.259 7.856 6.999 6.496 5.993 K0V 914 0
10 HD 36395 PM* 05 31 27.3958475290 -03 40 38.021551815 10.626 9.443 7.968 6.996 5.913 M1.5Ve 420 0
11 G 192-11 BY* 05 59 37.7518886225 +58 35 34.845182203       9.81   M0.0V 51 1
12 HD 42581 Fl* 06 10 34.6152510171 -21 51 52.658021185 10.801 9.607 8.125 7.164 6.121 M1V 386 0
13 BD+20 2465 ** 10 19 36.2808024653 +19 52 12.014037746   10.82 9.52 9.19   M4Vae 1119 0
14 BD+36 2322 BY* 12 57 40.2114201833 +35 13 30.069647793   12.2   10.137   M0V+M4/5V 210 2
15 BD+13 2618 Fl* 13 00 46.5602816848 +12 22 32.716799085 12.314 11.233 9.750 8.785 7.653 M0V 294 1
16 HD 118100 Fl* 13 34 43.2063348511 -08 20 31.335294003 11.578 10.552 9.372 8.602 7.930 K5Ve 322 0
17 HD 119850 Fl* 13 45 43.7754528655 +14 53 29.473195472 10.989 9.894 8.50 7.465 6.363 M2V 284 0
18 BD+55 1823 Fl* 16 17 05.3397894378 +55 16 08.810611864 12.00 10.92 9.46 9.552 8.55 M1.5Ve 173 0
19 Wolf 1130 Fl* 20 05 02.1949477691 +54 26 03.227818091   11.970 13.883     sdM1.5 115 0
20 V* AU Mic BY* 20 45 09.5323695486 -31 20 27.241710746   10.05 8.627 9.078 6.593 M1VeBa1 875 0
21 BD+40 883 SB* 21 00 05.3890094352 +40 04 12.684002015   11.6 9.969 9.634 7.96 M2.91 162 0
22 BD+40 883A PM* 21 00 05.4323880 +40 04 13.243765   12.29 10.49     M2.0V 6 0
23 * 61 Cyg B Fl* 21 06 55.2640651855 +38 44 31.362140913 8.63 7.40 6.03 4.86 3.55 K7V 662 1
24 CD-72 1700 ** 21 49 05.7565145368 -72 06 09.093515758 12.21 11.069 9.641 8.682 7.641 M1Ve 52 0
25 V* FK Aqr BY* 22 38 45.5745793091 -20 37 16.086999376 11.714 10.595 9.083 8.073 6.876 M0Vep 250 0
26 V* EV Lac Fl* 22 46 49.7311740821 +44 20 02.372223230   11.85 10.26 9.89   M4.0V 781 2
27 HD 216899 PM* 22 56 34.8047291749 +16 33 12.353727149 11.323 10.143 8.638 7.657 6.542 M1.5Ve 228 0
28 BD+00 5017 ** 23 35 00.2769821069 +01 36 19.433847921 12.082 10.893 9.546 8.703 7.879 K7V 127 0
29 BD-13 6464 ** 23 48 25.6960649528 -12 59 14.986223957   10.797 9.852 9.629   K5Vke 64 0

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2019.12.14-19:09:53

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