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


Query : 2013A&A...558A.141S

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 - 2022
#notes
1 V* GX And Er* 00 18 22.8849799680 +44 01 22.637951588   10.120   7.3   M2V 497 0
2 IC 348 OpC 03 44 32 +32 09.5           ~ 1301 1
3 Cl Melotte 22 OpC 03 46 24 +24 06.8           ~ 3185 0
4 Cl Melotte 25 OpC 04 29 47 +16 56.9           ~ 2844 0
5 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 2137 1
6 2MASS J05383858-0241558 Y*O 05 38 38.5944218448 -02 41 55.925390112 20.86 21.50 19.80 18.31 16.42 M5.5e 25 0
7 NAME sigma Orionis Cluster MGr 05 38 42 -02 36.0           ~ 522 0
8 2MASS J05385492-0228583 Y*O 05 38 54.9292657368 -02 28 58.375755156 21.05 20.21 18.61 17.22 15.48 M4.5 26 0
9 [W96] 4771-1075 TT* 05 39 05.4085005984 -02 32 30.366192804 17.541 15.79 14.42 13.54 12.70 K7e 28 0
10 Mayrit 425070 Y*O 05 39 11.4017533992 -02 33 32.831052984 21.773 21.52 19.94 18.32 16.43 M5e 26 0
11 2MASS J05392023-0238258 Y*O 05 39 20.2371430800 -02 38 25.948061736 21.41 20.82 18.97 17.45 15.55 M5.5 20 0
12 V* BX Ant TT* 10 18 28.6987521312 -31 50 02.830052544   13.39 11.454 11.382 9.325 M0Ve 110 0
13 BD+20 2465 Er* 10 19 36.2808181226 +19 52 12.010446571   10.82 9.52 9.19   dM3 1225 0
14 V* CE Ant TT* 10 42 30.1018928760 -33 40 16.229805204   12.21 10.91   9.10 M2Ve 179 1
15 DENIS J104814.6-395606 LM* 10 48 14.5736104113 -39 56 06.842743867     17.532 15.051 12.67 M8.5Ve: 121 0
16 V* TW Hya TT* 11 01 51.9053285064 -34 42 17.033218380   11.94 10.50 10.626 9.18 K6Ve 1736 1
17 NAME TW Hya Association As* 11 01.9 -34 42           ~ 884 0
18 CD-29 8887 TT* 11 09 13.7928873024 -30 01 39.968872752   12.95 11.119 10.642 8.875 M2Ve 118 0
19 V* V1215 Cen TT* 11 13 26.2208680752 -45 23 42.720964188     12.478   10.483 K8IVe 76 0
20 CD-34 7390A TT* 11 21 17.2193334624 -34 46 45.503251608   12.88 11.46 11.43 9.57 M1Ve 92 0
21 CD-34 7390B TT* 11 21 17.4430606440 -34 46 49.775810700   13.43 11.96 11.31 9.88 M1Ve 64 0
22 TWA 26 LM* 11 39 51.1378374696 -31 59 21.443660124         15.83 M8e 101 0
23 CD-36 7429B TT* 11 48 23.7348035520 -37 28 48.520414812   15.43 14.00   11.45 M1V 72 0
24 CD-36 7429A TT* 11 48 24.2227406904 -37 28 49.114270524   12.54 11.17 10.92 9.552 K5V 117 0
25 CD-36 7429 ** 11 48 24.22320 -37 28 49.1537           ~ 95 0
26 V* V1249 Cen TT* 12 15 30.7203201048 -39 48 42.606684144   13.09 11.160 10.919 9.50 M0.5 100 0
27 V* V1250 Cen TT* 12 34 20.4720080040 -48 15 19.545583716   13.3 12.2   11.80 M3 36 0
28 V* V1251 Cen TT* 12 34 20.6481372456 -48 15 13.531352148   13.3 12.2   11.90 M3.5 41 0
29 TWA 29 LM* 12 45 14.1607780560 -44 29 07.728263340         18.0 M9.5p 44 0
30 Sz 94 TT* 16 07 49.5974149968 -39 04 28.760342844   16.31 16.00 14.76 12.90 ~ 30 0
31 SONYC Lup3-5 LM* 16 08 16.0404001440 -39 03 04.320708732   17.74 19.92 18.15 15.28 M7.5 23 0
32 2MASS J16083578-3903479 Y*O 16 08 35.7826940376 -39 03 47.933557092   16.88 15.49 15.02 13.09 M6 23 0
33 Sz 107 Y*O 16 08 41.7980924472 -39 01 37.038551232   17.31 16.06 15.42 13.20 M5.5 32 0
34 Lupus 3 SFR 16 09.6 -39 03           ~ 299 0
35 THA 15-40 TT* 16 10 12.1994252424 -39 21 17.990363016   15.70 14.06 13.88 11.84 ~ 27 0
36 THA 15-41 TT* 16 10 16.4255309472 -39 08 05.033094180   15.33 13.73 13.28 12.12 M2 31 0
37 NAME Upper Sco Association As* 16 12 -23.4           ~ 1192 1
38 V* AU Mic LM* 20 45 09.5324974119 -31 20 27.237889841   10.05 8.627 9.078 6.593 M1VeBa1 1002 0
39 * 61 Cyg A BY* 21 06 53.9395895022 +38 44 57.902349973 7.50 6.39 5.21 4.19 3.54 K5V 991 0
40 * 61 Cyg B Er* 21 06 55.2638444466 +38 44 31.358519864 8.63 7.40 6.03 4.86 3.55 K7V 694 1
41 NAME eps Ori Cluster Cl* ~ ~           ~ 19 1

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2022.05.28-21:50:40

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