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Accreting protoplanets in the LkCa 15 transition disk
S Sallum1, K B Follette1,2, J A Eisner1
1Astronomy Department, University of Arizona, 933 North Cherry Avenue, Tucson, Arizona 85721, USA.
Astronomers directly detected gas accreting onto a protoplanet, LkCa 15 b, within a transition disk. This provides direct evidence of ongoing planet formation, a crucial step in understanding exoplanet demographics.
Area of Science:
- Astronomy and astrophysics
- Exoplanet research
- Planet formation studies
Background:
- Exoplanet discoveries offer insights into solar system architecture and planet demographics.
- Transition disks, with inner clearings, are key sites for studying planet formation.
- Direct observation of protoplanet accretion signatures has been challenging.
Purpose of the Study:
- To directly observe signatures of accretion onto protoplanets within a transition disk.
- To investigate the planet formation process in the LkCa 15 system.
- To probe the inner clearing of the LkCa 15 transition disk.
Main Methods:
- Utilized adaptive optics observations of the LkCa 15 system.
- Tracked source positions over multiple epochs (2009-2015) to infer orbital dynamics.
- Detected Hα emission to identify accreting gas.
Main Results:
- Inferred the presence of multiple companions on Keplerian orbits within the disk clearing.
- Directly detected Hα emission from the innermost companion, LkCa 15 b.
- Confirmed hot gas (approx. 10,000 K) accreting onto LkCa 15 b.
Conclusions:
- LkCa 15 b is an actively accreting protoplanet, providing direct evidence of ongoing planet formation.
- The findings support the role of planets in shaping transition disks.
- This study opens new avenues for observing and understanding protoplanet accretion.
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