J/A+A/668/A94 Accretion variability in RU Lup (Stock+, 2022)
Accretion variability in RU Lup.
Stock C., McGinnis P., Caratti o Garatti A., Natta A., Ray T.P.
<Astron. Astrophys. 668, A94 (2022)>
=2022A&A...668A..94S 2022A&A...668A..94S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, pre-main sequence ; Spectra, optical ; Equivalent widths
Keywords: stars: formation - stars: low-mass - stars: pre-main sequence -
stars: individual: RU Lup - accretion, accretion disks -
techniques: spectroscopic
Abstract:
The process of accretion in classical T Tauri stars (CTTSs) has been
observed to vary on different timescales. Studying this variability is
vital to understanding a star's evolution and provides insight into
the complex processes at work within, including sources of the veiling
present. Understanding the dichotomy between continuum veiling and
emission line veiling is integral to accurately measuring the amount
of veiling present in stellar spectra.
Here, 15 roughly consecutive nights of optical spectroscopic data from
the spectropolarimeter ESPaDOnS are utilised to characterise the
short-term accretion activity in the CTTS, RU Lup, and investigate its
relationship with the veiling in the LiI 6707Å absorption line.
The accretion-tracing HI Balmer series emission lines are studied and
used to obtain the accretion luminosity (Lacc) and mass accretion
rate (Macc) for each night, which vary by a factor of ∼2 between the
brightest and dimmest nights. We also measure the veiling using
multiple photospheric absorption lines (NaI 5688Å, MnI 6021Å,
and LiI 6707Å) for each night.
We find the LiI 6707Å line provides measurements of veiling that
produce a strong, positive correlation with L_acc in the star. When
corrected for Li depletion, the average veiling measured in the
LiI 6707Å line is rLiI(avg)=3.25±0.20, which is consistent with
the other photospheric lines studied (ravg=3.28±0.65).
We measure short timescale variability in the accretion luminosity and
mass accretion rate that are intrinsic and not due to geometric
effects. As the forbidden line emission we observe ([OI] 6300Å and
[SII] 6730Å) remains remarkably constant over our epochs, it is
clear that the variations in the mass accretion rate are too short to
have an effect on these outflow-tracers. Upon comparing the changes in
veiling and accretion luminosity, we find a strong, positive
correlation. This study provides an example of how this correlation
can be used as a tool to determine whether a measured variability is
due to extinction or an intrinsic change in accretion. As the
determination of veiling is an independent process from measuring
L_acc, their relationship allows further exploration of accretion
phenomena in young stars.
Description:
All these data are measured from flux calibrated spectra of ESPaDOnS
in from 08/06/2011 to 23/06/2011 of the classical T Tauri star RU Lup.
Table 2 contains the accretion luminosities, mass accretion rates
veilings from LiI, NaI, and MnI photospheric absorption lines, and the
Chi^2 value of the veiling fit for the LiI line. Tables A1 and A2
provide the integrated fluxes and equivalent widths (EW) of the
Halpha, Hbeta, Hgamma, Hdelta, HeI 5875A, and HeI 6678A emission lines
(and their associated errors). The table numbering (e.g. Table A1) is
such that it matches that of the tables in the paper.
Objects:
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RA (2000) DE Designation(s)
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15 56 42.31 -37 49 15.5 RU Lup = HIP 78094
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 66 12 Accretion luminosities, mass accretion rates
veilings from LiI, NaI, and MnI photospheric
absorption lines, and the Chi2 value of the
veiling fit for the LiI line
tablea1.dat 132 12 Integrated fluxes and equivalent widths (EW) of
the Halpha, Hbeta, Hgamma and Hdelta emission
lines (and their associated errors)
tablea2.dat 68 12 Integrated fluxes and equivalent widths (EW) of
the HeI 5875Å and HeI 6678Å emission
lines (and their associated errors)
list.dat 133 12 List of fits spectra
fits/* . 12 Individual fits spectra
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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 "date" Obs.Date Date of observation in format YYYY-MM-DD
12- 16 F5.2 [Lsun] logLacc Accretion luminosity in log
18- 21 F4.2 [Lsun] e_logLacc rms the standard deviation (sigma) of the
accretion luminosity
23- 27 F5.2 [Msun/yr] logMacc Mass accretion rate in log
29- 32 F4.2 --- rNaI Veiling measured in NaI 5688Å line
34- 37 F4.2 --- e_rNaI rms error in veiling from NaI line
39- 42 F4.2 --- rMnI ?=- Veiling measured in MnI 6021Å line
44- 47 F4.2 --- e_rMnI ?=- rms error in veiling from MnI line
49- 52 F4.2 --- rLiobs Veiling measured in LiI 6707Å line
(observed,pre-abundance correction)
54- 57 F4.2 --- rLiI Veiling measured in LiI 6707Å line
(post-abundance correction)
59- 62 F4.2 --- e_rLiI rms error in veiling from LiI line
64- 66 F3.1 --- chi2 chi2 value from the LiI 6707Å
veiling fit
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 "date" Obs.date Date of observation in format YYYY-MM-DD
12- 20 E9.4 mW/m2 FHa Integrated flux of the Halpha 6562Å line
22- 29 E8.3 mW/m2 e_FHa rms error in int. flux of Halpha line
31- 37 F7.2 0.1nm EWHa Equivalent width of Halpha line
39- 42 F4.2 0.1nm e_EWHa rms error in EW of Halpha
44- 51 E8.3 mW/m2 FHb Integrated flux of the Hbeta 4861Å line
53- 60 E8.3 mW/m2 e_FHb rms error in int. flux of Hbeta line
62- 67 F6.2 0.1nm EWHb Equivalent width of Hbeta line
69- 72 F4.2 0.1nm e_EWHb rms error in EW of Hbeta
74- 81 E8.3 mW/m2 FHg Integrated flux of the Hgamma 4340Å line
83- 90 E8.3 mW/m2 e_FHg rms error in int. flux of Hgamma line
92- 97 F6.2 0.1nm EWHg Equivalent width of Hgamma line
99-102 F4.2 0.1nm e_EWHg rms error in EW of Hgamma
104-111 E8.3 mW/m2 FHd Integrated flux of the Hdelta 4101Å line
113-120 E8.3 mW/m2 e_FHd rms error in int. flux of Hdelta line
122-127 F6.2 0.1nm EWHd Equivalent width of Hdelta line
129-132 F4.2 0.1nm e_EWHd rms error in EW of Hdelta
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Date Date of observation in format YYYY-MM-DD
12- 19 E8.3 mW/m2 FHeI5875 Integrated flux of the HeI 5875Å line
21- 28 E8.3 mW/m2 e_FHeI5875 rms error in int. flux of HeI 5875Å line
30- 34 F5.2 0.1nm EWHeI5875 Equivalent width of HeI 5875Å line
36- 39 F4.2 0.1nm e_EWHeI5875 rms error in EW of HeI 5875Å
41- 48 E8.3 mW/m2 FHeI6678 Integrated flux of the HeI 6678Å line
50- 57 E8.3 mW/m2 e_FHeI6678 rms error in int. flux of HeI 6678Å line
59- 63 F5.2 0.1nm EWHeI6678 Equivalent width of HeI 6678Å line
65- 68 F4.2 0.1nm e_EWHeI6678 rms error in EW of HeI 6678Å
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Right ascension (J2000)
4- 5 I2 min RAm Right ascension (J2000)
7- 11 F5.2 s RAs Right ascension (J2000)
12 A1 --- DE- Declination sign (J2000)
13- 14 I2 deg DEd Declination (J2000)
16- 17 I2 arcmin DEm Declination (J2000)
19- 22 F4.1 arcsec DEs Declination (J2000)
24- 29 I6 --- Nx Number of pixels along X-axis
31- 39 F9.3 d Obs.start Start date of observation (MJD)
41- 49 F9.3 d Obs.end End date of observation (MJD)
51- 54 I4 Kibyte size Size of FITS file
56- 76 A21 --- FileName Name of FITS file, in subdirectory fits
78-133 A56 --- Title Title of the FITS file
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History:
From Camille Stock, cstock(at)cp.dias.ie
Acknowledgements:
The authors would like to thank Juan Alcala and Jerome Bouvier for
insightful discussions on the topic. This project received funding
from the European Research Council under Advanced Grant No. 743029,
Ejection, Accretion Structures in YSOs (EASY).
(End) Patricia Vannier [CDS] 20-Oct-2022