Protoplanetary Disks around Sun-like Stars Appear to Live Longer When the Metallicity is Low*
Abstract Previous Hubble Space Telescope observations of the star-forming cluster NGC 346 in the Small Magellanic Cloud (SMC) revealed a large population of pre-main-sequence (PMS) candidates, characterized by H α excess emission in their photometry. However, without access to spectroscopy, the nature of these objects remained unclear. Using the NIRSpec instrument on board JWST, we studied a sample of these stars, with masses in the range of ∼0.9−1.8 M ⊙ , effective temperatures ( T eff ) in the range of 4500−8000 K, and PMS ages between ∼0.1 and 30 Myr. Here, we present the first spectra of solar-mass PMS stars in the metal-poor SMC ( Z = 1/8 Z ⊙ ) and discuss the physical properties of 10 representative sources with good signal-to-noise ratio. The observations indicate that even the oldest of these PMS candidates are still accreting gas with typical rates of ∼10 −8 M ⊙ yr −1 for stars older than ∼10 Myr, confirming their PMS nature. The spectra also reveal near-infrared excess and molecular hydrogen excitation lines consistent with the presence of disks around these stars. These findings suggest that in a low-metallicity environment, circumstellar disks can live longer than previously thought.
Authors
- C. D. Keyes (ORCID: https://orcid.org/0000-0002-4834-369X)
- Elena Sabbi (ORCID: https://orcid.org/0000-0003-2954-7643)
- Peter Zeidler (ORCID: https://orcid.org/0000-0002-6091-7924)
- Bernhard R. Brandl (ORCID: https://orcid.org/0000-0001-9737-169X)
- Giovanna Giardino (ORCID: https://orcid.org/0000-0002-9262-7155)
- Omnarayani Nayak (ORCID: https://orcid.org/0000-0001-6576-6339)
- M. Meixner (ORCID: https://orcid.org/0000-0002-0522-3743)
- Nolan Habel (ORCID: https://orcid.org/0000-0002-2667-1676)
- Katja Fahrion (ORCID: https://orcid.org/0000-0003-2902-8608)
- K. Biazzo (ORCID: https://orcid.org/0000-0002-1892-2180)
- Tracy L. Beck (ORCID: https://orcid.org/0000-0002-6881-0574)
- Massimo Robberto (ORCID: https://orcid.org/0000-0002-9573-3199)
- Conor Nally (ORCID: https://orcid.org/0000-0002-7512-1662)
- Guido De Marchi (ORCID: https://orcid.org/0000-0001-7906-3829)
- Laura Lenkić (ORCID: https://orcid.org/0000-0003-4023-8657)
- Alec S. Hirschauer (ORCID: https://orcid.org/0000-0002-2954-8622)
- Olivia Jones (ORCID: https://orcid.org/0000-0003-4870-5547)
- David R. Soderblom (ORCID: https://orcid.org/0000-0002-0322-8161)
- Ciarán Rogers (ORCID: https://orcid.org/0000-0001-5742-2261)
Publication Details
- Journal
- The Astrophysical Journal
- Published
- 2024-12-01
- DOI
- https://doi.org/10.3847/1538-4357/ad7a63
- Citations
- 9
- Primary Topic
- Astrophysics and Star Formation Studies
- Type
- article
- Field-Weighted Citation Impact
- 2.98
Funders
- National Aeronautics and Space Administration