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As the Worlds Turn: Constraining Spin Evolution in the Planetary-mass Regime
- Publication Year :
- 2020
- Publisher :
- American Astronomical Society, 2020.
-
Abstract
- To understand how planetary spin evolves and traces planet formation processes, we measure rotational line broadening in eight planetary-mass objects (PMOs) of various ages (1--800 Myr) using near-infrared high-resolution spectra from NIRSPEC/Keck. Combining these with published rotation rates, we compile 27 PMO spin velocities, 16 of which derive from our NIRSPEC/Keck program. Our data are consistent with spin velocities $v$ scaling with planetary radius $R$ as $v \propto 1/R$. We conclude that spin angular momentum is conserved as objects cool and contract over the sampled age range. The PMOs in our sample spin at rates that are approximately an order of magnitude below their break-up values, consistent with the hypothesis that they were spun down by magnetized circum-PMO disks (CPDs) during the formation era at ages $\lesssim$ a few Myr. There is a factor of 4--5 variation in spin velocity that has yet to be understood theoretically. It also remains to be seen whether spin evolves on timescales $\gtrsim$ 1 Gyr for PMOs, as it does for stars and high-mass brown dwarfs emitting magnetized winds.<br />accepted to ApJ
- Subjects :
- 010504 meteorology & atmospheric sciences
Brown dwarf
FOS: Physical sciences
Astrophysics
Astrophysics::Cosmology and Extragalactic Astrophysics
Rotation
01 natural sciences
Planet
0103 physical sciences
Astrophysics::Solar and Stellar Astrophysics
Spin (physics)
010303 astronomy & astrophysics
Solar and Stellar Astrophysics (astro-ph.SR)
Astrophysics::Galaxy Astrophysics
0105 earth and related environmental sciences
Line (formation)
Earth and Planetary Astrophysics (astro-ph.EP)
Physics
Computer Science::Information Retrieval
Astronomy and Astrophysics
Radius
Stars
Astrophysics - Solar and Stellar Astrophysics
Space and Planetary Science
Astrophysics::Earth and Planetary Astrophysics
Planetary mass
Astrophysics - Earth and Planetary Astrophysics
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....d1416576e04a089afdf74a9a843f0648