J/ApJ/925/21 IRTF/iSHELL K-band sp. obs. of PMS stars (Flores+, 2022)
The effects of starspots on spectroscopic mass estimates of low-mass young
stars.
Flores C., Connelley M.S., Reipurth B., Duchene G.
<Astrophys. J., 925, 21 (2022)>
=2022ApJ...925...21F 2022ApJ...925...21F
ADC_Keywords: YSOs; Spectra, infrared; Rotational velocities; Magnetic fields;
Spectral types; Stars, masses; Optical; Effective temperatures;
Stars, pre-main sequence
Keywords: Starspots ; Stellar magnetic fields ; Pre-main sequence stars ;
T Tauri stars ; High resolution spectroscopy
Abstract:
Magnetic fields and mass accretion processes create dark and bright
spots on the surface of young stars. These spots manifest as surface
thermal inhomogeneities, which alter the global temperature measured
on the stars. To understand the effects and implications of these
starspots, we conducted a large iSHELL high-resolution infrared
spectroscopic survey of T Tauri stars in Taurus-Auriga and Ophiuchus
star-forming regions. From the K-band spectra, we measured stellar
temperatures and magnetic field strengths using a magnetic radiative
transfer code. We compared our infrared-derived parameters against
literature optical temperatures and found (a) a systematic temperature
difference between optical and infrared observations, and (b) a
positive correlation between the magnetic field strengths and the
temperature differences. The discrepant temperature measurements imply
significant differences in the inferred stellar masses from stellar
evolutionary models. To discern which temperature better predicts the
mass of the star, we compared our model-derived masses against
dynamical masses measured from Atacama Large Millimeter/submillimeter
Array and the Plateau de Bure Interferometer for a subsample of our
sources. From this comparison we conclude that, in the range of
stellar masses from 0.3 to 1.3M☉, neither infrared nor optical
temperatures perfectly reproduce the stellar dynamical masses. But, on
average, infrared temperatures produce more precise and accurate
stellar masses than optical ones.
Description:
We observed 40 young stars between 2017 October 13 and 2020 October 23
using the high-resolution near-infrared echelle spectrograph iSHELL on
the Infrared Telescope Facility (IRTF). The observations were
performed in the K2 mode, thus from 2.09 to 2.38um, using the 0.75" slit
to achieve a spectral resolution of R∼50000.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 99 40 Stellar parameters of young stars derived from K band
table2.dat 70 40 Optical parameters from literature and derived masses
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See also:
J/AJ/130/1145 : YSO near-infrared properties (Doppmann+, 2005)
J/AJ/130/1733 : Optical spectroscopy of ρ Oph stars (Wilking+, 2005)
J/A+A/460/695 : Associations Containing Young stars (Torres+, 2006)
J/other/A+ARV/17.251 : Stars observed with Doppler imaging (Strassmeier, 2009)
J/ApJS/186/111 : Spitzer observations of Taurus members (Luhman+, 2010)
J/AJ/142/140 : Opt. spectroscopy of ρ Oph stars. II. (Erickson+, 2011)
J/ApJ/786/97 : Photospheric properties of T Tauri stars (Herczeg+, 2014)
J/MNRAS/441/2361 : Stellar magnetism, age and rotation (Vidotto+, 2014)
J/AJ/156/75 : Circumstellar disks in the Upper Sco assoc. (Esplin+, 2018)
J/MNRAS/482/698 : Oph DIsc Survey Employing ALMA (ODISEA). I. (Cieza+, 2019)
J/A+A/622/A72 : Intermediate-mass T Tau stars spectra (Villebrun+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Name of the star
12- 15 I4 K Tkband [3004/4400] K band temperature
17- 19 I3 K E_Tkband [10/142] Upper statistical K-band
temperature uncertainty (1)
21- 23 I3 K e_Tkband [7/169] Lower statistical K-band temperature
uncertainty (1)
25- 28 F4.2 [cm/s2] logg [3.1/4.4] Surface gravity in log10
30- 33 F4.2 [cm/s2] E_logg [0.02/0.4] Upper statistical surface gravity
uncertainty (1)
35- 38 F4.2 [cm/s2] e_logg [0.03/0.5] Lower statistical surface gravity
uncertainty (1)
40- 43 F4.2 --- veiling [0.03/4.15] Infrared K band veiling
45- 48 F4.2 --- E_veiling [0.01/0.5] Upper statistical infrared K band
veiling uncertainty (1)
50- 53 F4.2 --- e_veiling [0.01/0.7] Lower statistical infrared K band
veiling uncertainty (1)
55- 58 F4.2 m/s Vmicro [0.14/3.64] Micro turbulence
60- 63 F4.2 m/s E_Vmicro [0.17/1.1] Upper statistical micro
turbulence uncertainty (1)
65- 68 F4.2 m/s e_Vmicro [0.03/2.1] Lower statistical micro
turbulence uncertainty (1)
70- 73 F4.2 0.1T Bfield [0.7/3.3] Magnetic field strength in
deciTesla or kilogauss
75- 78 F4.2 0.1T E_Bfield [0.05/0.7] Upper statistical Magnetic field
strength uncertainty (1)
80- 83 F4.2 0.1T e_Bfield [0.06/0.8] Lower statistical Magnetic field
strength uncertainty (1)
85- 89 F5.2 m/s vsini [5.15/34.6] Projected rotational velocity
91- 94 F4.2 m/s E_vsini [0.07/2.7] Upper statistical projected
rotational velocity uncertainty (1)
96- 99 F4.2 m/s e_vsini [0.19/2.1] Lower statistical projected
rotational velocity uncertainty (1)
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Note (1): The reported uncertainties correspond to 3σ deviations from
the median value obtained from the MCMC distributions
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Name of the star (1)
12- 15 A4 --- SpT Adopted optical spectral type from literature
17- 20 I4 K Topt [3085/4710]? Optical temperature
22- 24 I3 K e_Topt [30/290]? Statistical Optical temperature
uncertainty
26 I1 --- r_SpT [1/8]? Reference for the adopted spectral
type (2)
28- 31 F4.2 Msun Mkband [0.3/1.5]? Stellar mass derived from K-band
temperature
33- 36 F4.2 Msun E_Mkband [0.02/0.2]? Upper statistical K-band derived
mass uncertainty
38- 41 F4.2 Msun e_Mkband [0.04/0.2]? Lower statistical K-band derived
mass uncertainty
43- 46 F4.2 Msun Mopt [0.4/1.7]? Stellar mass derived from optical
temperature
48 A1 --- l_Mopt [> ] Limit flag on the upper uncertainty
49- 52 F4.2 Msun E_Mopt [0.03/0.3]? Upper statistical Optical derived
mass uncertainty
54- 58 F5.3 Msun e_Mopt [0.03/0.3]? Lower statistical Optical derived
mass uncertainty
60- 64 F5.3 Msun Mdyn [0.1/1.27]? Dynamical mass
66- 70 F5.3 Msun e_Mdyn [0.01/0.3]? Statistical dynamical mass
uncertainty
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Note (1): As discussed in Manara+ (2019A&A...628A..95M 2019A&A...628A..95M),
Herczeg & Hillenbrand (2014, J/ApJ/786/97) defined V710 Tau A as the
southern companion and V710 Tau B as the Northern companion.
Note (2): Optical spectral type reference as follows:
1 = Herczeg & Hillenbrand et al. (2014, J/ApJ/786/97);
2 = Luhman et al. (2010, J/ApJS/186/111);
3 = Wilking et al. (2005, J/AJ/130/1733);
4 = Erickson et al. (2011, J/AJ/142/140);
5 = White & Hillenbrand (2004ApJ...616..998W 2004ApJ...616..998W);
6 = Torres et al. (2006, J/A+A/460/695);
7 = Bouvier & Appenzeller (1992A&AS...92..481B 1992A&AS...92..481B);
8 = Hartigan & Kenyon (2003ApJ...583..334H 2003ApJ...583..334H).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 28-Aug-2023