Protoplanetary Disks around Sun-like Stars Appear to Live Longer When the Metallicity is Low*
Year: 2024
Type: article
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 Hα 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.
Source: The Astrophysical Journal
Authors: Guido De Marchi, Giovanna Giardino, Katia Biazzo, Nino Panagia, Elena Sabbi, Tracy L. Beck, Massimo Robberto, Peter Zeidler, Olivia C. Jones, Margaret Meixner, Katja Fahrion, Nolan Habel, Conor Nally, Alec S. Hirschauer, David R. Soderblom, Omnarayani Nayak, Laura Lenkić, Ciaran Rogers, Bernhard Brandl, Charles D. Keyes
Institutions: European Space Research and Technology Centre, European Space Agency, Astronomical Observatory of Rome, National Institute for Astrophysics, Space Telescope Science Institute, NSF NOIRLab, International Gemini Observatory, Royal Observatory, UK Astronomy Technology Centre, Ames Research Center, Jet Propulsion Laboratory, University of Edinburgh, Goddard Space Flight Center, Leiden University, Leiden Observatory
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
OpenAlex ID: W4405434138