J/A+A/704/A42 Penellope VII. Accretion luminosity (Fiorellino+, 2025)
Penellope VII. Revisiting empirical relations to measure accretion luminosity.
Fiorellino E., Alcala J.M., Manara C.F., Pittman C.V., Abraham P.,
Venuti L., Cabrit S., Claes R., Fang M., Kospal A., Lodato G., Mauco K.,
Tychoniec L.
<Astron. Astrophys. 704, A42 (2025)>
=2025A&A...704A..42F 2025A&A...704A..42F (SIMBAD/NED BibCode)
ADC_Keywords: Stars, pre-main sequence ; Accretion ; Optical
Keywords: circumstellar matter - stars: formation - stars: low-mass -
stars: pre-main sequence - stars: solar-type -
stars: variables: T Tauri, Herbig Ae/Be
Abstract:
The accretion luminosity (Lacc) in young, low-mass stars is crucial
for understanding stellar formation. However, obtaining
direct measurements is often hindered by limited spectral coverage and
challenges in UV-excess modeling. Empirical relations linking Lacc to
various accretion tracers are widely used to overcome these
limitations.
This work revisits these empirical relations using the PENELLOPE
dataset, evaluating their applicability across different starforming
regions as well as accreting young objects other than Classical T
Tauri Stars (CTTSs; Class II sources).
We analyzed the PENELLOPE VLT/X-shooter dataset of 64 CTTSs, measuring
fluxes of several accretion tracers and adopting the stellar and
accretion parameters derived from studies based on PENELLOPE. For 61
sources, we supplemented our analysis with the ODYSSEUS HST data set,
which covers a wider spectral range in NUV bands.
We compared the Lacc values obtained in the PENELLOPE and ODYSSEUS
surveys, which employed a single hydrogen slab model (XS-fit) and a
multi-column accretion shock model (HST-fit), respectively, and found
statistically consistent results. Our analysis confirms that existing
empirical relations, previously derived for the Lupus sample, provide
reliable Lacc estimates for CTTSs in several other star-forming
regions. We revisit empirical relations for accretion tracers in our
dataset, based on HST-fit, with coefficients which are consistent
within 1σ with XS-fit results for most lines. We also propose a
method to estimate extinction using these relations and investigate
the empirical relations for Brackett lines (Br8 to Br21).
The Lacc-Lline empirical relations can be successfully used for
statistical studies of accretion on young forming objects in different
star-forming regions. These relations also offer a promising approach
to independently estimate extinction in CTTSs, provided a sufficient
number of flux-calibrated tracers are available across a broad
spectral range. We confirm that near-infrared lines (Paβ and
Brγ) serve as reliable tracers of Lacc in high accretors, making
them valuable tools for probing accretion properties of high accreting
young stars not accessible in the UVB.
Description:
In this study, we analyzed 64 X-Shooter spectra of CTTSs
from the PENELLOPE sample. For 61 of these CTTSs, we also used
quasi-contemporaneous HST spectra. We showed that the accretion
luminosities derived with the HST-fit and XS-fit methods are
statistically consistent, though significant differences may arise
for individual objects.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 141 68 The PENELLOPE sample
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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- 15 A15 --- Region Star Forming Region (Region)
17- 38 A22 --- Name Name of the Source (Name)
41- 42 I2 h RAh Right ascension (J2000)
44- 45 I2 min RAm Right ascension (J2000)
47- 51 F5.2 s RAs Right ascension (J2000)
53 A1 --- DE- Declination sign (J2000)
54- 55 I2 deg DEd Declination (J2000)
57- 58 I2 arcmin DEm Declination (J2000)
60- 63 F4.1 arcsec DEs Declination (J2000)
65- 67 F3.1 mag AvW Extinction computed using the weighted
coefficient method (Av_W)
69- 71 F3.1 mag e_AvW Lower error on AvW (dAv_Wminus)
73- 75 F3.1 mag E_AvW Upper error on AvW (dAv_Wplus)
77- 81 F5.2 [Lsun] logLaccW logarithm of the accretion luminosity
computed using line fluxes dereddened
with AvW (logLacc_W)
83- 86 F4.2 [Lsun] e_logLaccW Error on logLaccW (dlogLacc_W)
88- 90 F3.1 mag AvnotW Extinction computed using the unweighted
coefficient method (Av_notW)
92- 94 F3.1 mag e_AvnotW Lower error on AvnotW (dAv_notWminus)
96- 98 F3.1 mag E_AvnotW Upper error on AvnotW (dAv_notWplus)
100-104 F5.2 [Lsun] logLaccnotW logarithm of the accretion luminosity
computed using line fluxes dereddened
with AvnotW (logLacc_notW)
106-109 F4.2 [Lsun] e_logLaccnotW Error on logLaccnotW (dlogLacc_notW)
111-113 F3.1 mag Avdiff Extinction computed using the difference
method (Av_diff)
116-118 F3.1 mag e_Avdiff Lower error on Avdiff (dAvdiffminus)
120-122 F3.1 mag E_Avdiff Upper error on Avdiff (dAvdiffplus)
124-128 F5.2 [Lsun] logLaccdiff logarithm of the accretion luminosity
computed using line fluxes dereddened
with Av_diff (logLacc_diff)
130-133 F4.2 [Lsun] e_logLaccdiff Error on logLaccdiff (dlogLacc_diff)
135-141 F7.2 d deltaT ?=-99.9 Time interval between HST and XS
observation of the target (deltaT)
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Acknowledgements:
Eleonora Fiorellino, eleonora.fiorellino(at)unibo.it
References:
Manara et al., Paper I 2021A&A...650A.196M 2021A&A...650A.196M
Frasca et al., Paper II 2021A&A...656A.138F 2021A&A...656A.138F
Claes et al., Paper III 2022A&A...664L...7C 2022A&A...664L...7C
Gangi et al., Paper IV 2023A&A...675A.153G 2023A&A...675A.153G
Armeni et al., Paper V 2023A&A...679A..14A 2023A&A...679A..14A
Sperling et al., Paper VI 2024A&A...687A..54S 2024A&A...687A..54S
(End) Patricia Vannier [CDS] 13-Nov-2025