Mass constraints for 15 protoplanetary discs from HD 1–0

Springer Link (Chiba Institute of Technology)

Abstract

Context. Hydrogen deuteride (HD) rotational line emission can provide reliable protoplanetary disc gas mass measurements, but this molecule is difficult to observe and detections have been limited to three T Tauri discs. No new data have been available since the Herschel Space Observatory mission ended in 2013. Aims. We set out to obtain new disc gas mass constraints by analysing upper limits on HD 1–0 emission in Herschel /PACS archival data from the DIGIT key programme. Methods. With a focus on the Herbig Ae/Be discs, whose stars are more luminous than T Tauris, we determined upper limits for HD in data previously analysed for its line detections. We studied the significance of these limits with a grid of models run with the DALI physical-chemical code, customised to include deuterium chemistry. Results. Nearly all the discs are constrained to M gas ≤ 0.1 M ⊙ , ruling out global gravitational instability. A strong constraint is obtained for the HD 163296 disc mass, M gas ≤ 0.067 M ⊙ , implying Δ g/d ≤ 100. This HD-based mass limit is towards the low end of CO-based mass estimates for the disc, highlighting the large uncertainty in using only CO and suggesting that gas-phase CO depletion in HD 163296 is at most a factor of a few. The M gas limits for HD 163296 and HD 100546, both bright discs with massive candidate protoplanetary systems, suggest disc-to-planet mass conversion efficiencies of M p /( M gas + M p ) ≈ 10–40% for present-day values. Near-future observations with SOFIA/HIRMES will be able to detect HD in the brightest Herbig Ae/Be discs within 150 pc with ≈ 10 h integration time.

Authors 9

1. Mihkel Kama

   University of Cambridge · Tartu Observatory

   Affiliation as printed

   Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK

   Tartu Observatory, Observatooriumi 1, Tõravere 61602, Tartu, Estonia

2. Leon Trapman Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands

3. D. Fedele

   Arcetri Astrophysical Observatory

   Affiliation as printed

   INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy

4. S. Bruderer

   Max Planck Institute for Extraterrestrial Physics

   Affiliation as printed

   Max-Planck-institute für extraterrestrische Physic, Giessenbachstraße, 85748 Garching bei München, Germany

5. M. R. Hogerheijde

   Tartu Observatory · University of Amsterdam

   Affiliation as printed

   Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1090 GE Amsterdam, The Netherlands

   Tartu Observatory, Observatooriumi 1, Tõravere 61602, Tartu, Estonia

6. Anna Miotello

   European Southern Observatory

   Affiliation as printed

   European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany

7. Ewine F. van Dishoeck

   Tartu Observatory · Max Planck Institute for Extraterrestrial Physics

   Affiliation as printed

   Max-Planck-institute für extraterrestrische Physic, Giessenbachstraße, 85748 Garching bei München, Germany

   Tartu Observatory, Observatooriumi 1, Tõravere 61602, Tartu, Estonia

8. Catherine J. Clarke

   University of Cambridge

   Affiliation as printed

   Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK

9. Edwin A. Bergin

   University of Michigan

   Affiliation as printed

   Department of Astronomy, University of Michigan, 1085 S. University Ave, Ann Arbor, MI 48109, USA