PENELLOPE

Astronomy and Astrophysics, vol. 704, pp. A42

Abstract

Context . The accretion luminosity ( L acc ) 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 L acc to various accretion tracers are widely used to overcome these limitations. Aims . This work revisits these empirical relations using the PENELLOPE dataset, evaluating their applicability across different star-forming regions as well as accreting young objects other than Classical T Tauri Stars (CTTSs; Class II sources). Methods . 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. Results . We compared the L acc 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 L acc 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 1 σ 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). Conclusions . The L acc − L line 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 (Pa β and Br γ ) serve as reliable tracers of L acc in high accretors, making them valuable tools for probing accretion properties of high accreting young stars not accessible in the UVB.

Authors 12

1. Eleonora Fiorellino

   Universidad de La Laguna · Astronomical Observatory of Capodimonte · Instituto de Astrofísica de Canarias · National Institute for Astrophysics

   Affiliation as printed

   Departamento de Astrofísica, Universidad de La Laguna

   INAF-Osservatorio Astronomico di Capodimonte

   Instituto de Astrofísica de Canarias, IAC, Vía Láctea s/n

2. J. M. Alcalá

   Astronomical Observatory of Capodimonte · National Institute for Astrophysics

   Affiliation as printed

   INAF-Osservatorio Astronomico di Capodimonte

3. Carlo Felice Manara

   European Southern Observatory · European Southern Observatory

   Affiliation as printed

   European Southern Observatory

4. Caeley V. Pittman

   Boston University

   Affiliation as printed

   Department of Astronomy, Boston University

   Institute for Astrophysical Research, Boston University

5. P. Ábrahám

   Eötvös Loránd University · University of Vienna · Konkoly Observatory · HUN-REN Research Centre for Astronomy and Earth Sciences

   Affiliation as printed

   Institute for Astronomy (IfA), University of Vienna

   Institute of Physics and Astronomy, ELTE Eötvös Loránd University

   Konkoly Observatory, HUN-REN Research Centre for Astronomy and Earth Sciences, MTA Centre of Excellence

6. L. Venuti

   Search for Extraterrestrial Intelligence

   Affiliation as printed

   SETI Institute

7. S. Cabrit

   Centre National de la Recherche Scientifique · Université Paris Sciences et Lettres · Observatoire de Paris · Sorbonne Université · Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères · Institut de Planétologie et d'Astrophysique de Grenoble · Université Grenoble Alpes

   Affiliation as printed

   Observatoire de Paris – PSL University, Sorbonne Université, LERMA, CNRS

   Univ. grenoble Alpes, CNRS, IPAG

8. R. A. B. Claes

   European Southern Observatory · European Southern Observatory

   Affiliation as printed

   European Southern Observatory

9. Á. Kóspál

   Eötvös Loránd University · Konkoly Observatory · Max Planck Institute for Astronomy · HUN-REN Research Centre for Astronomy and Earth Sciences

   Affiliation as printed

   Institute of Physics and Astronomy, ELTE Eötvös Loránd University

   Konkoly Observatory, HUN-REN Research Centre for Astronomy and Earth Sciences, MTA Centre of Excellence

   Max-Planck-Insitut für Astronomie

10. Giuseppe Lodato

    University of Milan

    Affiliation as printed

    Dipartimento di Fisica, Università degli Studi di Milano

11. Karina Maucó

    European Southern Observatory · European Southern Observatory

    Affiliation as printed

    European Southern Observatory

12. Łukasz Tychoniec Aachen Leiden Observatory

    Leiden University · Leiden Observatory

    Affiliation as printed

    Leiden Observatory, Leiden University