J/A+A/551/A107 X-shooter spectra of 24 young stellar objects (Manara+, 2013)
X-shooter spectroscopy of young stellar objects.
II. Impact of chromospheric emission on accretion rate estimates.
Manara C.F., Testi L., Rigliaco E., Alcala J.M., Natta A., Stelzer B.,
Biazzo K., Covino E., Covino S., Cupani G., D'Elia V., Randich S.
<Astron. Astrophys., 551, A107 (2013)>
=2013A&A...551A.107M 2013A&A...551A.107M
ADC_Keywords: Stars, pre-main sequence ; Spectroscopy ; Equivalent widths
Keywords: stars: pre-main sequence - stars: low-mass - stars: activity
Abstract:
The lack of knowledge of photospheric parameters and the level of
chromospheric activity in young low-mass pre-main sequence stars
introduces uncertainties when measuring mass accretion rates in
accreting (Class II) young stellar objects. A detailed investigation
of the effect of chromospheric emission on the estimates of mass
accretion rate in young low-mass stars is still missing. This can be
undertaken using samples of young diskless (Class III) K and M-type
stars.
Our is to measure the chromospheric activity of Class III pre main
sequence stars to determine its effect on the estimates of the
accretion luminosity (Lacc) and mass accretion rate (dMacc/dt) in
young stellar objects with disks.
Using VLT/X-shooter spectra, we analyzed a sample of 24 nonaccreting
young stellar objects of spectral type between K5 and M9.5. We
identified the main emission lines normally used as tracers of
accretion in Class II objects, and we determined their fluxes in order
to estimate the contribution of the chromospheric activity to the line
luminosity.
We have used the relationships between line luminosity and accretion
luminosity derived in the literature for Class II objects to evaluate
the impact of chromospheric activity on the accretion rate
measurements. We find that the typical chromospheric activity would
bias the derived accretion luminosity by Lacc,noise<10-3L☉, with
a strong dependence on the Teff of the objects. The noise on Macc
depends on stellar mass and age, and the typical values of
log(Macc,noise) range between ~-9.2 to -11.6M☉/yr. Values of
Lacc<10-3L☉ obtained in accreting low-mass pre main sequence
stars through line luminosity should be treated with caution because
the line emission may be dominated by the contribution of
chromospheric activity.
Description:
Reduced, flux- and wavelength-calibrated, telluric corrected 1-d
spectra of all the 24 objects considered in this work. Each object's
spectrum is divided in the three arms of X-Shooter, namely the UVB
arm, the VIS arm, and the NIR arm. The spectra are given in fits
format and are not corrected for extinction, but the objects are known
to have low Av (<0.2mag).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 143 24 Known parameters from the literature
table3.dat 38 24 Stellar parameters derived for the objects
in our sample
table4.dat 60 24 Spectral types obtained using the method based
on the spectral indices described in Sect. 3
and in Appendix B
tableb1.dat 110 12 Near-IR spectral indices
table6.dat 195 24 Fluxes and equivalent widths of Balmer lines
table7.dat 160 24 Fluxes and equivalent widths of He and Ca lines
refs.dat 69 29 References
spectra.dat 69 24 X-shooter spectra of ClassIII YSOs
sp/* . 72 Individual UVB, Visual and near-IR spectra in FITS
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See also:
J/A+A/548/A56 : X-shooter spectra of 12 young stellar objects (Rigliaco+, 2012)
J/A+A/561/A2 : 36 accreting YSOs emission lines (Alcala+, 2014)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Source name
12- 35 A24 --- OName Other names
37- 38 I2 h RAh Right ascension (J2000)
40- 41 I2 min RAm Right ascension (J2000)
43- 47 F5.2 s RAs Right ascension (J2000)
49 A1 --- DE- Declination sign (J2000)
50- 51 I2 deg DEd Declination (J2000)
53- 54 I2 arcmin DEm Declination (J2000)
56- 60 F5.2 arcsec DEs Declination (J2000)
62- 72 A11 --- Region Region: Lup III, TW Hya, or σ Ori
74- 76 I3 pc Dist Distance (1)
78- 81 A4 --- Sp.l MK spectral type from literature
83- 87 F5.2 mag Umag ?=- U magnitude
89- 93 F5.2 mag Bmag ?=- B magnitude
95- 99 F5.2 mag Vmag ?=- V magnitude
101-105 F5.2 mag Rmag ?=- R magnitude
107-111 F5.2 mag Imag ?=- I magnitude
113-117 F5.2 mag Jmag ?=- J magnitude
119-123 F5.2 mag Hmag ?=- H magnitude
125-129 F5.2 mag Kmag ?=- K magnitude
131-143 A13 --- Ref References, in refs.dat file
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Note (1): Distances to TW Hya objects are obtained by Weinberger et al.
(2013ApJ...762..118W 2013ApJ...762..118W), by Torres et al. (2008, Handbook of Star Forming
Regions, 2, 757), and by Mamajek (2005ApJ...634.1385M 2005ApJ...634.1385M),
to sigma Ori by Brown et al. (1994, Cat. J/A+A/289/101), and
to Lupus III by Comeron (2008, Handbook of Star Forming Regions, 42, 295).
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Source name
13- 16 A4 --- SpT MK spectral type (2)
18- 21 I4 K Teff Effective temperature (2)
23- 27 F5.2 [Lsun] log(L*) stellar luminositiy
29- 32 F4.2 Msun M* Stellar mass
34- 38 F5.2 [Lsun] <Lacc> Average accretion luminosity
<log(Lacc,noise)> (see sec. 6)
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Note (2): The spectral type-Teff relation is adopted from Luhman et al.
(2003, Cat. J/ApJ/593/1093) for M-type objects and from Kenyon & Hartmann
(1995, Cat. J/ApJS/101/117) for K-type objects.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Source name
12- 15 A4 --- SpT MK spectral type derived from this work,
as explained in Sect. 3.1
17- 20 A4 --- Sp.V MK spectral type obtained using the spectral
indices in the VIS part of the spectrum,
as explained in Sect. 3.2
22- 25 A4 --- Sp.1 MK spectral type obtained using H2O-K2 index (3)
27- 30 A4 --- Sp.5 MK spectral type obtained using H2O index (3)
32- 35 A4 --- Sp.8 MK spectral type obtained using sH2Oj index (3)
37- 40 A4 --- Sp.11 MK spectral type obtained using sH2Ok index (3)
42- 45 A4 --- Sp.9 MK spectral type obtained using sH2OH1 index (3)
47- 50 A4 --- Sp.2 MK spectral type obtained using Ij index (3)
52- 55 A4 --- Sp.3 MK spectral type obtained using IH index (3)
57- 60 A4 --- Sp.12 Spectral type obtained using HP index (3)
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Note (3): All the columns refer to the results obtained using NIR spectral
indices, as explained in Appendix B. SpType are reported only in the range of
validity of each index. Indexes are defined in tableb1.dat.
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Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- Index Index name
9- 15 A7 --- Range Range of validity
17- 39 A23 --- Num Numerator [nm]
41- 69 A29 --- Den Denominator [nm]
71-110 A40 --- Ref Reference
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Source name
12- 17 F6.3 10-17W/m2 F(Ha) Hα flux (10-14erg/cm2/s)
19- 23 F5.3 10-17W/m2 e_F(Ha) rms uncertainty on F(Ha)
25 A1 --- l_F(Hb) Limit flag on F(Hb)
26- 32 F7.4 10-17W/m2 F(Hb) Hβ flux (10-14erg/cm2/s)
34- 38 F5.3 10-17W/m2 e_F(Hb) ? rms uncertainty on F(Hb)
39 A1 --- l_F(Hg) Limit flag on F(Hg)
40- 46 F7.4 10-17W/m2 F(Hg) Hγ flux (10-14erg/cm2/s)
48- 53 F6.4 10-17W/m2 e_F(Hg) ? rms uncertainty on F(Hg)
54 A1 --- l_F(Hd) Limit flag on F(Hd)
55- 61 F7.4 10-17W/m2 F(Hd) Hδ flux (10-14erg/cm2/s)
63- 68 F6.4 10-17W/m2 e_F(Hd) ? rms uncertainty on F(Hd)
69 A1 --- l_F(H8) Limit flag on F(H8)
70- 76 F7.4 10-17W/m2 F(H8) H8 flux (10-14erg/cm2/s)
78- 83 F6.4 10-17W/m2 e_F(H8) ? rms uncertainty on F(H8)
84 A1 --- l_F(H9) Limit flag on F(H9)
85- 90 F6.4 10-17W/m2 F(H9) H9 flux (10-14erg/cm2/s)
92- 97 F6.4 10-17W/m2 e_F(H9) ? rms uncertainty on F(H9)
98 A1 --- l_F(H10) Limit flag on F(H10)
99-106 F8.6 10-17W/m2 F(H10) H10 flux (10-14erg/cm2/s)
108-113 F6.4 10-17W/m2 e_F(H10) ? rms uncertainty on F(H10)
114 A1 --- l_F(H11) Limit flag on F(H11)
115-122 F8.6 10-17W/m2 F(H11) H11 flux (10-14erg/cm2/s)
124-129 F6.4 10-17W/m2 e_F(H11) ? rms uncertainty on F(H11)
131-135 F5.1 km/s Ha.1 Hα10% width
137-140 F4.2 --- Bj Balmer jump ratio, intened as F360/F400,
(fluxes at ∼360nm and ∼400nm)
142-147 F6.2 0.1nm W(Ha) ?=- Hα equivalent width
149-154 F6.2 0.1nm W(Hb) ?=- Hβ equivalent width
156-161 F6.2 0.1nm W(Hg) ?=- Hγ equivalent width
163-168 F6.2 0.1nm W(Hd) ?=- Hδ equivalent width
170-175 F6.2 0.1nm W(H8) ?=- H8 equivalent width
177-182 F6.2 0.1nm W(H9) ?=- H9 equivalent width
184-189 F6.2 0.1nm W(H10) ?=- H10 equivalent width
191-195 F5.2 0.1nm W(H11) ?=- H11 equivalent width
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Source name
12 A1 --- l_F(5876) Limit flag on F(5876)
13- 20 E8.3 mW/m2 F(5876) HeI λ587.6 flux
22- 29 E8.3 mW/m2 e_F(5876) ? rms uncertainty on F(5876)
31 A1 --- l_F(10836) Limit flag on HeI2
32- 39 E8.3 mW/m2 F(10836) HeI λ1083.6 flux
41- 48 E8.3 mW/m2 e_F(10836) ? rms uncertainty on F(10836)
50 A1 --- l_F(3934) Limit flag on F(3934)
51- 58 E8.3 mW/m2 F(3934) CaII λ393.4 flux
60- 67 E8.3 mW/m2 e_F(3934) ? rms uncertainty on F(3934)
69 A1 --- l_F(8499) Limit flag on F(8499)
70- 77 E8.3 mW/m2 F(8499) CaII λ849.9 flux
79- 86 E8.3 mW/m2 e_F(8499) ? rms uncertainty on F(8499)
88 A1 --- l_F(8542) Limit flag on F(8542)
89- 96 E8.3 mW/m2 F(8542) CaII λ854.2 flux
98-105 E8.3 mW/m2 e_F(8542) ? rms uncertainty on F(8542)
107 A1 --- l_F(8662) Limit flag on F(8662)
108-115 E8.3 mW/m2 F(8662) CaII λ866.2 flux
117-124 E8.3 mW/m2 e_F(8662) ? rms uncertainty on F(8662)
126-130 F5.2 0.1nm W(5876) ?=- HeI λ587.6 equivalent width
132-136 F5.2 0.1nm W(10836) ?=- HeI λ1083.6 equivalent width
138-143 F6.2 0.1nm W(3934) ?=- CaII λ393.4 equivalent width
145-149 F5.2 0.1nm W(8499) ?=- CaII λ849.9 equivalent width
151-155 F5.2 0.1nm W(8542) ?=- CaII λ854.2 equivalent width
157-160 F4.2 0.1nm W(8662) ?=- CaII λ866.2 equivalent width
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Ref Reference number
4- 22 A19 --- BibCode BibCode
24- 42 A19 --- Aut Author's name
45- 69 A25 --- Com Comments
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Byte-by-byte Description of file: spectra.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Object name
12- 15 A4 --- SpT Spectral type of the object, this paper
18- 29 A12 --- UVB UVB (330-550nm) spectrum in subdirectory sp
32- 43 A12 --- VIS VIS (550-1000nm) spectrum in subdirectory sp
46- 57 A12 --- NIR NIR (1000-2400nm) spectrum in subdirectory sp
59- 61 F3.1 arcsec SlU Width of the UVB slit
63- 65 F3.1 arcsec SlV Width of the VIS slit
67- 69 F3.1 arcsec SlN Width of the NIR slit
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Acknowledgements:
Carlo Felice Manara, cmanara(at)eso.org
References:
Rigliaco et al., Paper I 2012A&A...548A..56R 2012A&A...548A..56R, Cat. J/A+A/548/A56
Stelzer et al., Paper III 2013A&A...558A.141S 2013A&A...558A.141S
Alcala et al., Paper IV 2014A&A...561A...2A 2014A&A...561A...2A, Cat. J/A+A/561/A2
(End) Carlo Felice Manara [ESO], Patricia Vannier [CDS] 08-Mar-2014