Deep H α Imaging Survey of IC 348 with the Hubble Space Telescope. I. Accretion Properties of Stellar and Substellar Objects
7 affiliations
- 1University of California
- 2The University of Texas at Austin
- 3University of Virginia
- 4Center for Astrophysics—Harvard & Smithsonian
- 5California Institute of Technology
- 6Australian National University
- 7University of Nevada
Abstract
Accretion governs the growth of young stars and the early evolution of their circumstellar disks, yet population-level measurements of accretion are often hampered by heterogeneous diagnostics and by samples preferentially selected toward disk-bearing or accreting objects. This can impact the mass accretion rate–stellar mass ( M ̇ – M ⋆ ) relation, particularly at substellar masses. We present a uniform analysis of accretion in the ∼2 Myr old star-forming cluster IC 348 based on deep Hubble Space Telescope (HST) F656N imaging. Using H α excess as a single, homogeneous accretion tracer, we derive accretion rates and robust upper limits for 200 cluster members spanning the stellar-to-substellar mass regime (3 M ⊙ to 4 M Jup ). Accretion is detected in 37% ± 3% of the sample, with fractions of 34% ± 4% among stellar members and 46% ± 6% among substellar objects. For accretors alone, the inferred M ̇ – M ⋆ relation is consistent with those measured in similarly aged regions such as Lupus. In contrast, including weak accretors and nondetections increases the scatter and flattens the slope while lowering the intercept, demonstrating the strong influence of the low-accretion tail on population-level accretion relations. For free-floating planetary-mass objects in IC 348, extrapolating the accretors-only fit overpredicts M ̇ by approximately an order of magnitude compared to the fit that includes upper limits, which instead implies mass accretion rates of <10 ⁻¹² M ⊙ yr ⁻¹ . These results show that sample selection—specifically whether the sample is restricted to disk-bearing or accreting targets or instead is drawn from a complete membership census—is a dominant factor shaping population-level accretion relations across a wide dynamic range in stellar mass.
Versions
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BibTeX
@article{jiang2026deep,
title = {{Deep H α Imaging Survey of IC 348 with the Hubble Space Telescope. I. Accretion Properties of Stellar and Substellar Objects}},
author = {Lillian Yushu Jiang and Brendan P. Bowler and Yifan Zhou and Adam L. Kraus and Sean M. Andrews and Lynne A. Hillenbrand and Michael J. Ireland and Zhaohuan Zhu},
journal = {The Astronomical Journal},
year = {2026},
month = oct,
doi = {10.3847/1538-3881/aea84d},
url = {https://iopscience.iop.org/article/10.3847/1538-3881/aea84d},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Deep H α Imaging Survey of IC 348 with the Hubble Space Telescope. I. Accretion Properties of Stellar and Substellar Objects
AU - Lillian Yushu Jiang
AU - Brendan P. Bowler
AU - Yifan Zhou
AU - Adam L. Kraus
AU - Sean M. Andrews
AU - Lynne A. Hillenbrand
AU - Michael J. Ireland
AU - Zhaohuan Zhu
PY - 2026
DA - 2026/10/28
JO - The Astronomical Journal
DO - 10.3847/1538-3881/aea84d
UR - https://iopscience.iop.org/article/10.3847/1538-3881/aea84d
AB - Accretion governs the growth of young stars and the early evolution of their circumstellar disks, yet population-level measurements of accretion are often hampered by heterogeneous diagnostics and by samples preferentially selected toward disk-bearing or accreting objects. This can impact the mass accretion rate–stellar mass ( M ̇ – M ⋆ ) relation, particularly at substellar masses. We present a uniform analysis of accretion in the ∼2 Myr old star-forming cluster IC 348 based on deep Hubble Space Telescope (HST) F656N imaging. Using H α excess as a single, homogeneous accretion tracer, we derive accretion rates and robust upper limits for 200 cluster members spanning the stellar-to-substellar mass regime (3 M ⊙ to 4 M Jup ). Accretion is detected in 37% ± 3% of the sample, with fractions of 34% ± 4% among stellar members and 46% ± 6% among substellar objects. For accretors alone, the inferred M ̇ – M ⋆ relation is consistent with those measured in similarly aged regions such as Lupus. In contrast, including weak accretors and nondetections increases the scatter and flattens the slope while lowering the intercept, demonstrating the strong influence of the low-accretion tail on population-level accretion relations. For free-floating planetary-mass objects in IC 348, extrapolating the accretors-only fit overpredicts M ̇ by approximately an order of magnitude compared to the fit that includes upper limits, which instead implies mass accretion rates of <10 ⁻¹² M ⊙ yr ⁻¹ . These results show that sample selection—specifically whether the sample is restricted to disk-bearing or accreting targets or instead is drawn from a complete membership census—is a dominant factor shaping population-level accretion relations across a wide dynamic range in stellar mass.
SN - 0004-6256
SN - 1538-3881
ER -