2013A&A...558A.141S


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.08CEST03:03:13

2013A&A...558A.141S - Astronomy and Astrophysics, volume 558A, 141-141 (2013/10-1)

X-shooter spectroscopy of young stellar objects. III. Photospheric and chromospheric properties of Class III objects.

STELZER B., FRASCA A., ALCALA J.M., MANARA C.F., BIAZZO K., COVINO E., RIGLIACO E., TESTI L., COVINO S. and D'ELIA V.

Abstract (from CDS):

Traditionally, the chromospheres of late-type stars are studied through their strongest emission lines, Hα and CaIIHK emission. Our knowledge on the whole emission line spectrum is more elusive as a result of the limited spectral range and sensitivity of most available spectrographs. We intend to reduce this gap with a comprehensive spectroscopic study of the chromospheric emission line spectrum of a sample of non-accreting pre-main sequence stars (ClassIII sources). We analyzed X-shooter/VLT spectra of 24 ClassIII sources from three nearby star-forming regions (σOrionis, LupusIII, and TWHya). We determined the effective temperature, surface gravity, rotational velocity, and radial velocity by comparing the observed spectra with synthetic BT-Settl model spectra. We investigated in detail the emission lines emerging from the stellar chromospheres and combined these data with archival X-ray data to allow for a comparison between chromospheric and coronal emissions. For some objects in the sample the atmospheric and kinematic parameters are presented here for the first time. The effective temperatures are consistent with those derived for the same stars from an empirical calibration with spectral types. Small differences in the surface gravity found between the stars can be attributed to differences in the average age of the three star-forming regions. The strength of lithium absorption and radial velocities confirm the young age of all but one object in the sample (Sz94). Both X-ray and Hα luminosity as measured in terms of the bolometric luminosity are independent of the effective temperature for early-M stars but decline toward the end of the spectral M sequence. For the saturated early-M stars the average emission level is almost one dex higher for X-rays than for Hα: log(Lx/Lbol)=-2.85±0.36 vs. log(L/Lbol)=-3.72±0.21. When all chromospheric emission lines (including the Balmer series up to H11, CaiiHK, the Caiiinfrared triplet, and several Hei lines) are summed up the coronal flux still dominates that of the chromosphere, typically by a factor 2-5. Flux-flux relations between activity diagnostics that probe different atmospheric layers (from the lower chromosphere to the corona) separate our sample of active pre-main sequence stars from the bulk of field M dwarfs studied in the literature. Flux ratios between individual optical emission lines show a smooth dependence on the effective temperature. The Balmer decrements can roughly be reproduced by an NLTE radiative transfer model devised for another young star of similar age. Future, more complete chromospheric model grids can be tested against this data set.

Abstract Copyright:

Journal keyword(s): stars: pre-main sequence - stars: activity - stars: chromospheres - stars: coronae - stars: fundamental parameters

Simbad objects: 41

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Number of rows : 41

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 V* GX And Er* 00 18 22.8849667932 +44 01 22.637271919   10.120   7.3   M2V 448 0
2 IC 348 OpC 03 44 34 +32 09.8           ~ 1227 1
3 Cl Melotte 22 OpC 03 47 00 +24 07.0           ~ 2978 0
4 Cl Melotte 25 OpC 04 26 54.00 +15 52 00.0           ~ 2654 0
5 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 1977 1
6 2MASS J05383858-0241558 Y*O 05 38 38.5945611243 -02 41 55.919882016 20.86 21.50 19.80 18.31 16.42 M5.5e 24 0
7 NAME sigma Orionis Cluster MGr 05 38 42 -02 36.0           ~ 486 0
8 2MASS J05385492-0228583 Y*O 05 38 54.9294057342 -02 28 58.375274422 21.05 20.21 18.61 17.22 15.48 M4.5 24 0
9 [W96] 4771-1075 LM* 05 39 05.4085166628 -02 32 30.366076729 17.541 15.79 14.42 13.54 12.70 K7e 22 0
10 Mayrit 425070 Y*O 05 39 11.4014704592 -02 33 32.826664924 21.773 21.52 19.94 18.32 16.43 M5e 25 0
11 2MASS J05392023-0238258 Y*O 05 39 20.2374400819 -02 38 25.947658082 21.41 20.82 18.97 17.45 15.55 M5.5 18 0
12 V* BX Ant TT* 10 18 28.6989165716 -31 50 02.826261802   13.39 11.454 11.382 9.325 M0Ve 103 0
13 BD+20 2465 Er* 10 19 36.2808024653 +19 52 12.014037746   10.82 9.52 9.19   M4Vae 1145 0
14 V* CE Ant TT* 10 42 30.1021269333 -33 40 16.226774953   12.21 10.91   9.10 M2Ve 151 1
15 DENIS J104814.6-395606 LM* 10 48 14.5734267094 -39 56 06.843210566     17.532 15.051 12.67 M8.5Ve: 114 0
16 V* TW Hya TT* 11 01 51.9054298616 -34 42 17.031550898   11.94 10.50 10.626 9.18 K6Ve 1532 1
17 NAME TW Hya Association As* 11 01.9 -34 42           ~ 819 0
18 CD-29 8887 TT* 11 09 13.8074415397 -30 01 40.070212113   12.95 11.119 10.642 8.875 M2Ve 111 0
19 V* V1215 Cen TT* 11 13 26.2208332352 -45 23 42.719174706     12.478   10.483 K8IVe 68 0
20 CD-34 7390A TT* 11 21 17.2193442623 -34 46 45.500772910   12.88 11.46 11.43 9.57 M1Ve 83 0
21 CD-34 7390B TT* 11 21 17.4429759333 -34 46 49.774537089   13.43 11.96 11.31 9.88 M1Ve 57 0
22 TWA 26 LM* 11 39 51.1435262748 -31 59 21.473337261         15.83 M8e 96 0
23 CD-36 7429B TT* 11 48 23.7347470027 -37 28 48.519698919   15.43 14.00   11.45 M1V 66 0
24 CD-36 7429A TT* 11 48 24.2226856081 -37 28 49.112368947   12.54 11.17 10.92 9.552 K5V 107 0
25 CD-36 7429 ** 11 48 24.22320 -37 28 49.1537           ~ 92 0
26 V* V1249 Cen TT* 12 15 30.7203284919 -39 48 42.605543199   13.09 11.160 10.919 9.50 M0.5 83 0
27 V* V1250 Cen TT* 12 34 20.4718890806 -48 15 19.545698484   13.3 12.2   11.80 M3 34 0
28 V* V1251 Cen TT* 12 34 20.6481566533 -48 15 13.530604360   13.3 12.2   11.90 M3.5 39 0
29 TWA 29 LM* 12 45 14.1609543807 -44 29 07.737190128         18.0 M9.5p 42 0
30 Sz 94 TT* 16 07 49.5977000657 -39 04 28.760980696   16.31 16.00 14.76 12.90 ~ 27 0
31 SONYC Lup3-5 LM* 16 08 16.0418067283 -39 03 04.322083980   17.74 19.92 18.15 15.28 M7.5 19 0
32 2MASS J16083578-3903479 Y*O 16 08 35.7827668528 -39 03 47.934787375   16.88 15.49 15.02 13.09 M6 20 0
33 Sz 107 Y*O 16 08 41.7994782799 -39 01 37.026638986   17.31 16.06 15.42 13.20 M5.5 28 0
34 NAME Lupus III SFR 16 09.6 -39 03           ~ 271 0
35 THA 15-40 TT* 16 10 12.1994267530 -39 21 17.991359231   15.70 14.06 13.88 11.84 ~ 23 0
36 THA 15-41 TT* 16 10 16.4254785450 -39 08 05.033811326   15.33 13.73 13.28 12.12 M2 28 0
37 NAME Upper Sco Association As* 16 12 -23.4           ~ 1021 1
38 V* AU Mic BY* 20 45 09.5323695486 -31 20 27.241710746   10.05 8.627 9.078 6.593 M1VeBa1 893 0
39 * 61 Cyg A BY* 21 06 53.9396100677 +38 44 57.897024357 7.50 6.39 5.21 4.19 3.54 K5V 945 0
40 * 61 Cyg B Fl* 21 06 55.2640651855 +38 44 31.362140913 8.63 7.40 6.03 4.86 3.55 K7V 667 1
41 NAME eps Ori Cluster Cl* ~ ~           ~ 19 1

    Equat.    Gal    SGal    Ecl

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2020.07.08-03:03:13

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