2017A&A...605A..86M


Query : 2017A&A...605A..86M

2017A&A...605A..86M - Astronomy and Astrophysics, volume 605A, 86-86 (2017/9-1)

An extensive VLT/X-shooter library of photospheric templates of pre-main sequence stars.

MANARA C.F., FRASCA A., ALCALA J.M., NATTA A., STELZER B. and TESTI L.

Abstract (from CDS):

Context. Studies of the formation and evolution of young stars and their disks rely on knowledge of the stellar parameters of the young stars. The derivation of these parameters is commonly based on comparison with photospheric template spectra. Furthermore, chromospheric emission in young active stars impacts the measurement of mass accretion rates, a key quantity for studying disk evolution.
Aims. Here we derive stellar properties of low-mass (M*≤2M) pre-main sequence stars without disks, which represent ideal photospheric templates for studies of young stars. We also use these spectra to constrain the impact of chromospheric emission on the measurements of mass accretion rates. The spectra are reduced, flux-calibrated, and corrected for telluric absorption, and are made available to the community.
Methods. We derive the spectral type for our targets by analyzing the photospheric molecular features present in their VLT/X-shooter spectra by means of spectral indices and comparison of the relative strength of photospheric absorption features. We also measure effective temperature, gravity, projected rotational velocity, and radial velocity from our spectra by fitting them with synthetic spectra with the ROTFIT tool. The targets have negligible extinction (AV<0.5mag) and spectral type from G5 to K6, and from M6.5 to M8. They thus complement the library of photospheric templates presented in our previous publication. We perform synthetic photometry on the spectra to derive the typical colors of young stars in different filters. We measure the luminosity of the emission lines present in the spectra and estimate the noise due to chromospheric emission in the measurements of accretion luminosity in accreting stars.
Results. We provide a calibration of the photospheric colors of young pre-main sequence stars as a function of their spectral type in a set of standard broad-band optical and near-infrared filters. The logarithm of the noise on the accretion luminosity normalized to the stellar luminosity is roughly constant and equal to ~-2.3 for targets with masses larger than 1 solar mass, and decreases with decreasing temperatures for lower-mass stars. For stars with masses of ∼1.5M and ages of ∼1-5Myr, the chromospheric noise converts to a limit of measurable mass accretion rates of ∼3x10–10M/yr. The limit on the mass accretion rate set by the chromospheric noise is of the order of the lowest measured values of mass accretion rates in Class II objects.

Abstract Copyright: © ESO, 2017

Journal keyword(s): stars: pre-main sequence - stars: chromospheres - stars: formation - stars: low-mass - stars: variables: T Tauri, Herbig Ae/Be - stars: variables: T Tauri, Herbig Ae/Be

VizieR on-line data: <Available at CDS (J/A+A/605/A86): spectra.dat sp/*>

Simbad objects: 25

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Number of rows : 25
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 2MASS J03283450+3100510 Y*O 03 28 34.501 +31 00 51.01           ~ 72 0
2 V* V1077 Tau Or* 04 34 18.0303957624 +18 30 06.519662280   13.70       G8 77 0
3 HD 285957 TT* 04 38 39.0722950320 +15 46 13.573577352   11.75 10.863   9.616 K2 42 0
4 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 4095 0
5 HD 30171 TT* 04 45 51.2948260920 +15 55 49.632455460   10.12 9.36   8.439 G5 46 0
6 V* V1354 Tau TT* 04 57 30.6551084688 +20 14 29.585897268   11.94 11.09 10.85 9.938 K1 29 0
7 NAME Garrison 1 OpC 05 38 42 -02 36.0           ~ 537 0
8 NAME TW Hya Association As* 11 01.9 -34 42           ~ 907 0
9 NAME Cha 1 MoC 11 06 48 -77 18.0           ~ 1095 1
10 [LES2004] ChaI 717 LM* 11 08 02.3404943112 -76 40 34.367766528       18.21 15.46 M6 10 0
11 CHXX 16 LM* 11 10 22.2523149192 -76 25 13.841167332         16.58 ~ 30 0
12 [LES2004] ChaI 601 LM* 11 12 30.9867590712 -76 53 34.193460948           M7 11 0
13 2MASS J11195652-7504529 Y*O 11 19 56.5183658640 -75 04 52.911244884         16.68 M7.25 9 0
14 TWA 26 LM* 11 39 51.1378374696 -31 59 21.443660124         15.83 M8e 103 0
15 V* LQ Lup TT* 15 08 37.7353724976 -44 23 17.049423444 11.46 11.54 10.645 10.22 9.804 G8IVe 80 0
16 V* LT Lup TT* 15 15 45.3719328096 -33 31 59.725104132 12.00 11.61 10.670 10.17 9.574 K0e 28 0
17 V* MS Lup TT* 15 25 59.6471855904 -45 01 15.821666004 11.97 11.67 10.969 10.42 10.041 G7IV 29 0
18 RX J1538.6-3916 TT* 15 38 38.2726392807 -39 16 55.360567832   12.64 11.61 11.21   K4 17 0
19 V* MU Lup TT* 15 40 41.1704779152 -37 56 18.539934828     12.35     K6 18 0
20 2MASS J15430624-3920194 TT* 15 43 06.2455060656 -39 20 19.483625508     12.25     K6 14 0
21 CD-39 10162 TT* 15 47 41.7650471808 -40 18 26.748166644 12.58 12.33 11.158 10.75 10.047 K1e 26 0
22 NAME Lupus Complex SFR 16 03 -38.1           ~ 643 0
23 CD-25 11330 TT* 16 05 50.6524391928 -25 33 13.618314720   11.87 10.895   9.797 K1V(e) 23 0
24 CD-25 11378 TT* 16 08 43.4068352136 -26 02 16.794704112   11.16 10.380   9.265 G9V(e) 29 0
25 NAME Upper Sco Association As* 16 12 -23.4           ~ 1252 1

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2023.02.01-08:14:53

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