J/A+A/708/A22 Accretion diagnostics with JWST/MIRI of YSOs (Shridharan+, 2026) ================================================================================ Improving accretion diagnostics for young stellar objects with mid-infrared Hydrogen lines from JWST/MIRI. Shridharan B., Manoj P., Chandra Pathak V. , Caratti o Garatti A., Banerjee B., Henning T., Kamp I., van Dishoeck E., Tyagi H., Arun R., Mathew B., Guedel M., Lagage P.-O. =2026A&A...708A..22S (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: YSOs ; Stars, nearby ; Spectroscopy ; Infrared sources ; Line Profiles ; References ; Positional data ; Extinction ; Mass loss ; Stars, distances Keywords: accretion, accretion disks - line: identification - techniques: spectroscopic - protoplanetary disks - stars: pre-main sequence stars - variables: T Tauri, Herbig Ae/Be Abstract: We present a comprehensive study of mid-infrared neutral hydrogen (HI) emission lines in 79 nearby (d<200pc) young stars using the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI). This work extends accretion diagnostics to mid-infrared HI transitions, which are less affected by extinction and outflow emission compared to optical and near-infrared HI lines. We aim to identify mid-infrared HI transitions that can serve as reliable accretion diagnostics in young stars, and evaluate their utility in deriving physical conditions of the accreting gas. We identify and measure 22 HI transitions in the MIRI wavelength regime (5-28{mu}m) and perform LTE slab modelling to re- move the H_2_O contribution from selected HI transitions. We examine the spatial extent of MIR HI emission and assess contamination from molecular and jet-related emission. We find that mid-IR HI line emission is spatially compact, even for sources with spatially extended [NeII] and [FeII] jets, suggesting minimal contamination from extended jet. Although Pfund {alpha} (HI 6-5) and Humphreys {alpha} (HI 7-6) are the strongest lines in the mid-infrared, they are blended with H2O transitions. This blending necessitates additional processing to remove molecular contamination, thereby limiting their use as accretion diagnostics. Instead, we identify the HI (8-6) at 7.502{mu}m and HI (10-7) at 8.760{mu}m transitions as better alternatives, as they are largely unaffected by molecular contamination and offer a more reliable means of measuring accretion rates from MIRI spectra. We provide updated empirical relations for converting mid-IR HI line luminosities into accretion luminosity for 6 different HI lines in the MIRI wavelength range. Moreover, comparison of observed line ratios with theoretical models shows that MIR HI lines offer robust constraints on the hydrogen gas density in accretion columns, n_H_=10^10.6^ to 10^11.2^cm^-3^ in most stars, with some stars exhibiting lower densities (<10^10^cm^-3^), approaching the optically thin regime. Description: The tablea1.dat contains the fundamental stellar parameters (Distance, Extinction, Spectral Type) collected from literature or Gaia DR3, along with reference mass accretion rates. The table2.dat contains the newly measured line luminosities and derived accretion properties from publicly available JWST/MIRI observations data. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file tablea1.dat 97 79 Stellar parameters of the nearby YSOs tablea2.dat 175 79 *Measured H I line luminosities, newly derived accretion luminosities and mass accretion rate -------------------------------------------------------------------------------- Note on tablea2.dat: JWST-MIRI log(L_acc_) and dM_acc_/dt values calculated using the empirical relations established in this work for four H I transitions: (6-5), (7-6), (8-6), and (10-7). The line luminosity values are corrected for molecular contamination wherever possible. -------------------------------------------------------------------------------- See also: J/A+A/689/A270 : An all-sky catalogue of stellar reddening values (Paunzen+, 2024) J/A+A/667/A124 : GIARPS T Tauri spectra (GHOsT) (Gangi+, 2022) J/A+A/666/A55 : Accretion variability monitoring in the ONC (Flaischlen+, 2022) J/ApJ/653/657 : Spectroscopic observations of Herbig Ae/Be stars (Manoj+, 2006) J/A+A/620/A128 : Gaia DR2 study of Herbig Ae/Be stars (Vioque+, 2018) J/A+A/600/A20 : Lupus YSOs X-shooter spectroscopy (Alcala+, 2017) J/A+A/579/A66 : Accretion in {rho}-Ophiucus (Manara+, 2015) J/A+A/570/A82 : Mapping accretion variability in NGC 2264 (Venuti+, 2014) J/A+A/561/A2 : 36 accreting YSOs emission lines (Alcala+, 2014) J/A+A/548/A56 : X-shooter spectra of 12 young stellar objects (Rigliaco+, 2012) J/A+A/452/245 : Near-IR photometry of PMS stars in rho Oph (Natta+, 2006) J/A+A/365/90 : NIR H lines in TTS (Folha+, 2001) J/ApJ/921/72 : Class II and III disks with Gaia and ALMA data (Michel+, 2021) J/ApJ/895/38 : MIR extinction toward Cyg OB2-12 ISM (Hensley+, 2020) J/ApJ/893/56 : T Tauri star IR excesses & Ha eq. widths (Manzo-Martinez+, 2020) J/ApJ/849/63 : FIR-mm data of YSOs in star-forming regions (Ribas+, 2017) J/ApJ/847/31 : Protoplanetary disk data in Cha I and Lupus (Mulders+, 2017) J/ApJ/841/116 : Herschel spectra of 11 very low mass stars (Hendler+, 2017) J/ApJ/786/97 : Photospheric properties of T Tauri stars (Herczeg+, 2014) J/ApJ/769/149 : IR spectroscopy in Orion A: transitional disks (Kim+, 2013) J/ApJ/769/21 : Accretion luminosities of young stars from Pf{beta} (Salyk+, 2013) J/ApJ/745/19 : Binary systems in Taurus-Auriga (Kraus+, 2012) J/ApJ/744/121 : Far-UV spectroscopy of T Tau stars (Yang+, 2012) J/ApJ/724/835 : The Spitzer c2d survey of WTTSs. III. (Wahhaj+, 2010) J/ApJ/703/1964 : Spectra of three nearby star-forming regions (Furlan+, 2009) J/ApJ/693/L81 : Extinction in star-forming regions (McClure, 2009) J/ApJS/264/41 : Stellar radii & extinctions from APOGEE, GALAH & RAVE (Yu+, 2023) J/ApJS/220/11 : SEDs of Spitzer YSOs in the Gould Belt (Dunham+, 2015) J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009) J/AJ/166/175 : Pre- and main sequence stars properties (Fernandes+, 2023) J/AJ/163/174 : IRTF/VLT M-band spectroscopic survey (Banzatti+, 2022) J/AJ/160/44 : Upper Scorpius spectroscopy and photometry (Luhman+, 2020) J/MNRAS/493/234 : Herbig Ae/Be accretion rates & mechanisms (Wichittanakom+ 2020) J/MNRAS/471/770 : Parameters and IR excesses of Gaia DR1 stars (McDonald+,2017) J/MNRAS/453/976 : Herbig Ae/Be X-shooter observations (Fairlamb+, 2015) II/354 : HIP and TGAS stars reddening and extinction (Gontcharov+, 2018) II/366 : ASAS-SN catalog of variable stars (Jayasinghe+, 2018-2020) Byte-by-byte Description of file: tablea1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 19 A19 --- Name Name of the nearby young stars YSO (Source) 21- 30 F10.6 deg RAdeg Right ascension (J2000) (RA_deg) 32- 40 F9.5 deg DEdeg Declination (J2000) (Dec_deg) 42- 50 A9 --- SpType Spectral types (SpType) 52- 55 I4 --- PropID Observational JWST/MIRI proposal ID (PropID) 57- 62 F6.2 pc D ? Stellar distance from GaiaDR3 or from Manara et al. (2023ASPC..534..539M) (Dist_pc) 64- 68 F5.2 mag AV Optical V-band line of sight extinction (Av_mag) 70- 76 F7.3 [Msun/yr] log(dM/dt) ? The mass accretion rates from Manara et al. (2023ASPC..534..539M) (logMacc) 78- 83 F6.3 Lsun L* ? Stellar luminosity (Lstar) 85- 91 F7.4 [Lsun] logLacc ? The accretion luminosity (logLacc) 93- 97 A5 --- Refs Literature references (Refs) (1) -------------------------------------------------------------------------------- Note (1): Literature references are as follows: 1 = Manara et al. 2023ASPC..534..539M, 31 sources in our sample 2 = Rigliaco et al. 2015ApJ...801...31R, 11 sources in our sample 3 = Herczeg & Hillenbrand 2014ApJ...786...97H, Cat. J/ApJ/786/97, 10 sources in our sample 4 = Salyk et al. 2013ApJ...769...21S, Cat. J/ApJ/769/21, 7 sources in our sample 5 = Evans et al. 2009ApJS..181..321E, Cat. J/ApJS/181/321, 7 sources in our sample 6 = Furlan et al. 2009ApJ...703.1964F, Cat. J/ApJ/703/1964, 7 sources in our sample 7 = Mulders et al. 2017ApJ...847...31M, Cat. J/ApJ/847/31, 8 sources in our sample 8 = Wichittanakom et al. 2020MNRAS.493..234W, Cat. J/MNRAS/493/234, 5 sources in our sample 9 = Manara et al. 2014A&A...568A..18M, 1 source in our sample 10 = Manara et 2015A&A...579A..66M, Cat. J/A+A/579/A66, 1 source in our sample 11 = Dunham et al. 2015ApJS..220...11D, Cat. J/ApJS/220/11, 6 sources in our sample 12 = Kim et al. 2013ApJ...769..149K, Cat. J/ApJ/769/149, 2 sources in our sample 13 = Manara et al. 2017A&A...604A.127M, 1 source in our sample 14 = Manoj et al. 2006ApJ...653..657M, Cat. J/ApJ/653/657, 2 sources in our sample 15 = Michel et al. 2021ApJ...921...72M, Cat. J/ApJ/921/72, 4 sources in our sample 16 = Gangi et al. 2022A&A...667A.124G, Cat. J/A+A/667/A124, 1 source in our sample 17 = Garufi et al. 2014A&A...567A.141G, 1 source in our sample 18 = Ribas et al. 2017ApJ...849...63R, Cat. J/ApJ/849/63, 2 sources in our sample 19 = McDonald et al. 2017MNRAS.471..770M, Cat. J/MNRAS/471/770, 2 sources in our sample 20 = Salyk et al. 2013ApJ...769...21S, Cat. J/ApJ/769/21, 1 source in our sample 21 = Gontcharov & Mosenkov 2018MNRAS.475.1121G, 2 sources in our sample 22 = Sullivan et al. 2022AJ....164..100S, 2 sources in our sample 23 = Wahhaj et al. 2010ApJ...724..835W, Cat. J/ApJ/724/835, 4 sources in our sample 24 = Yang et al. 2012ApJ...744..121Y, Cat. J/ApJ/744/121, 2 sources in our sample 25 = Alcala et al. 2017A&A...600A..20A, Cat. J/A+A/600/A20, 2 sources in our sample 26 = Vioque et al. 2018A&A...620A.128V, Cat. J/A+A/620/A128, 2 sources in our sample 27 = Paunzen et al. 2024A&A...689A.270P, Cat. J/A+A/689/A270, 1 source in our sample 28 = Hendler et al. 2017ApJ...841..116H, Cat. J/ApJ/841/116, 1 source in our sample 29 = Manzo-Martinez et al. 2020ApJ...893...56M, Cat. J/ApJ/893/56, 1 source in our sample 30 = Yu et al. 2023ApJS..264...41Y, Cat. J/ApJS/264/41, 1 source in our sample 31 = Fernandes et al. 2023AJ....166..175F, Cat. J/AJ/166/175, 1 source in our sample 32 = Luhman & Esplin 2020AJ....160...44L, Cat. J/AJ/160/44, 1 source in our sample 33 = Dahm & Carpenter 2009AJ....137.4024D, 1 source in our sample 34 = Natta et al. 2006A&A...452..245N, Cat. J/A+A/452/245, 1 source in our sample 35 = Jayasinghe et al. 2018MNRAS.477.3145J, Cat. II/366, 1 source in our sample 36 = Fairlamb et al. 2015MNRAS.453..976F, Cat. J/MNRAS/453/976, 1 source in our sample ------------------------------------------------------------------------------- Byte-by-byte Description of file: tablea2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 19 A19 --- Name Name of the nearby young stars YSO (Source) 21 A1 --- l_logL65 Upper limit of logL65 23- 27 F5.2 [Lsun] logL65 Line luminosity of HI(6-5) transition at 7.46{mu}m (L65) 29- 32 F4.2 [Lsun] e_logL65 ? Uncertainty of logL65 (errL65) 34 A1 --- l_logL76 Upper limit of logL76 36- 40 F5.2 [Lsun] logL76 Line luminosity of HI(7-6) transition at 12.37{mu}m (L76) 42- 45 F4.2 [Lsun] e_logL76 ? Uncertainty of logL76 (errL76) 47 A1 --- l_logL86 Upper limit of logL86 49- 53 F5.2 [Lsun] logL86 Line luminosity of HI(8-6) transition at 7.50{mu}m (L86) 55- 58 F4.2 [Lsun] e_logL86 ? Uncertainty of logL86 (errL86) 60 A1 --- l_logL107 Upper limit of logL107 62- 66 F5.2 [Lsun] logL107 Line luminosity of HI(10-7) transition at 8.76{mu}m (L107) 68- 71 F4.2 [Lsun] e_logL107 ? Uncertainty of logL107 (errL107) 73 A1 --- l_logLa65 Upper limit of logLa65 75- 79 F5.2 [Lsun] logLa65 Derived accretion luminosity derived with logL65 (La65) 81- 84 F4.2 [Lsun] e_logLa65 ? Uncertainty of logLa65 (errLa65) 86 A1 --- l_logLa76 Upper limit of logLa76 88- 92 F5.2 [Lsun] logLa76 Derived accretion luminosity derived with logL76 (La76) 94- 97 F4.2 [Lsun] e_logLa76 ? Uncertainty of logLa76 (errLa76) 99 A1 --- l_logLa86 Upper limit of logLa86 101-105 F5.2 [Lsun] logLa86 Derived accretion luminosity derived with logL86 (La86) 107-110 F4.2 [Lsun] e_logLa86 ? Uncertainty of logLa86 (errLa86) 112 A1 --- l_logLa107 Upper limit of logLa107 114-118 F5.2 [Lsun] logLa107 Derived accretion luminosity derived with logL107 (La107) 120-123 F4.2 [Lsun] e_logLa107 ? Uncertainty of logLa107 (errLa107) 125 A1 --- l_log(dMa65/dt) Upper limit of logMa65 127-131 F5.2 [Msun/yr] log(dMa65/dt) ? Derived mass accretion rates derived with logL65 (Ma65) 133-136 F4.2 [Msun/yr] e_log(dMa65/dt) ? Uncertainty of logMa65 (errMa65) 138 A1 --- l_log(dMa76/dt) Upper limit of logMa76 140-144 F5.2 [Msun/yr] log(dMa76/dt) ? Derived mass accretion rates derived with logL76 (Ma76) 146-149 F4.2 [Msun/yr] e_log(dMa76/dt) ? Uncertainty of logMa76 (errMa76) 151 A1 --- l_log(dMa86/dt) Upper limit of logMa86 153-157 F5.2 [Msun/yr] log(dMa86/dt) ? Derived mass accretion rates derived with logL86 (Ma86) 159-162 F4.2 [Msun/yr] e_log(dMa86/dt) ? Uncertainty of logMa86 (errMa86) 164 A1 --- l_log(dMa107/dt) Upper limit of logMa107 166-170 F5.2 [Msun/yr] log(dMa107/dt) ? Derived mass accretion rates derived with logL107 (Ma107) 172-175 F4.2 [Msun/yr] e_log(dMa107/dt) ? Uncertainty of logMa107 (errMa107) -------------------------------------------------------------------------------- Acknowledgements: Baskaran Shridharan, shridharan.1997(at)gmail.com ================================================================================ (End) Luc Trabelsi [CDS] 04-Dec-2025