J/A+A/648/A121 X-ray activity and accretion in the ONC (Flaischlen+, 2021)
Testing the models of X-ray driven photoevaporation with accreting stars in the
Orion Nebula Cluster.
Flaischlen S., Preibisch T., Manara C.F., Ercolano B.
<Astron. Astrophys. 648, A121 (2021)>
=2021A&A...648A.121F 2021A&A...648A.121F (SIMBAD/NED BibCode)
ADC_Keywords: Stars, pre-main sequence ; YSOs ; X-ray sources ; Accretion
Keywords: protoplanetary disks - stars: pre-main sequence -
(stars:) planetary systems - stars: statistics - X-rays: stars
Abstract:
Recent works highlight the importance of stellar X-rays on the
evolution of the circumstellar disks of young stellar objects,
especially for disk photoevaporation.
A signature of this process may be seen in the so far tentatively
observed dependence of stellar accretion rates on X-ray luminosities.
According to models of X-ray driven photoevaporation, stars with
higher X-ray luminosities should show lower accretion rates, on
average, in a sample with similar masses and ages.
To this aim, we have analyzed X-ray properties of young stars in the
Orion Nebula Cluster determined with Chandra during the COUP
observation as well as accretion data obtained from the photometric
catalog of the HST Treasury Program. With these data, we have
performed a statistical analysis of the relation between X-ray
activity and accretion rates using partial linear regression analysis.
The initial anticorrelation found with a sample of 332 young stars is
considerably weaker compared to previous studies. However, excluding
flaring activity or limiting the X-ray luminosity to the soft band
(0.5-2.0keV) leads to a stronger anticorrelation, which is
statistically more significant. Furthermore, we have found a weak
positive correlation between the higher component of the plasma
temperature gained in the X-ray spectral fitting and the accretion
rates, indicating that the hardness of the X-ray spectra may influence
the accretion process.
There is evidence for a weak anticorrelation, as predicted by
theoretical models, suggesting that X-ray photoevaporation modulates
the accretion rate through the inner disk at late stages of disk
evolution, leading to a phase of photoevaporation-starved accretion.
Description:
X-ray luminosities and accretion rates as well as masses and ages for
the stars in our sample.
The X-ray data is from the Chandra Orion Ultradeep Project (COUP), see
Getman et al. (2005ApJS..160..319G 2005ApJS..160..319G, Cat. J/ApJS/160/319). The stellar
mass, the isochronal age, the accretion luminosity and the accretion
rate are from Manara et al. (2012ApJ...755..154M 2012ApJ...755..154M, Cat. J/ApJ/755/154).
The data was used to produce Fig. 5 and Fig. A1 in the article.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
data.dat 63 332 Stellar parameters
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See also:
J/ApJS/160/319 : COUP: observations and source lists (Getman+, 2005)
J/ApJ/755/154 : Mass accretion rates from HST in the ONC (Manara+, 2012)
Byte-by-byte Description of file: data.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- COUP COUP identification number (1)
7- 14 F8.5 deg RAdeg Right ascension (J2000) (2)
17- 24 F8.5 deg DEdeg Declination (J2000) (2)
27 A1 --- Meth [0/1] Method used to determine the accretion
rates (3)
30- 33 F4.2 Msun Mass Stellar mass (2)
36- 39 F4.2 [yr] logAge Logarithm of the isochronal age (2)
42- 49 F8.5 [10-7W] logLX Logarithm of the X-ray luminosity (4)
52- 56 F5.2 [Lsun] logLacc Logarithm of the accretion luminosity (2)
58- 63 F6.2 [Msun/yr] logdM/dt Logarithm of the mass accretion rate (2)
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Note (1): X-ray data from the Chandra Orion Ultradeep Project (COUP), see
Getman et al. (2005ApJS..160..319G 2005ApJS..160..319G, Cat. J/ApJS/160/319).
Note (2): Accretion rates and stellar parameters from Manara et al.
(2012ApJ...755..154M 2012ApJ...755..154M, Cat. J/ApJ/755/154).
The mass, the isochronal age and the accretion rate were determined using
the evolutionary models of Siess et al. (2000A&A...358..593S 2000A&A...358..593S).
Note (3): Method used to determine the accretion rates as follows:
0 = 2CD method is based on the U-band excess,
1 = Halpha method on the equivalent width of the Halpha emission,
see Manara et al. (2012ApJ...755..154M 2012ApJ...755..154M, Cat. J/ApJ/755/154).
Note (4): LogLX is the total X-ray luminosity corrected for interstellar
absorption, corresponding to the total 0.5-8.0keV band.
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Acknowledgements:
Stefan Flaischlen, sflaisch(at)usm.lmu.de
(End) S. Flaischlen [Univ.-Sternwarte Muenchen], P. Vannier [CDS] 23-Feb-2021