[Astronomy seminar] Next Friday Astro seminar Oct 12 @10:30 in FC61

[Astronomy seminar announcements]

Dear all,
welcome to the next astro seminar appointment. The speaker of this week is Prof. Jonathan Tan from Chalmers University of Technology & the Univ. of Virginia.
The seminar will be in room FC61 on Friday 12th of October at 10:30 am.
Title and abstract are included below and now available on the albanova agenda.

Kind regards,
Angela & Alexis

https://www.albanova.se/event/inside-out-planet-formation/


Inside-Out Planet Formation

Abstract: The Kepler-discovered systems with tightly-packed inner planets (STIPs), typically with several planets of Earth to super-Earth masses on well-aligned, sub-AU orbits may host the most common type of planets in the Galaxy. They pose a great challenge for planet formation theories, which fall into two broad classes: (1) formation in the outer disk followed by inward migration; (2) formation in situ. I review the pros and cons of these classes, before focusing on a new theory of sequential in situ formation from the inside-out via creation of successive gravitationally unstable rings fed from a continuous stream of small (~cm-m size) "pebbles," drifting inward via gas drag. Pebbles first collect at the pressure trap associated with the transition from a magnetorotational instability (MRI)-inactive ("dead zone") region to an inner MRI-active zone. A pebble ring builds up until it either becomes gravitationally unstable to form an Earth to super-Earth-mass planet directly or induces gradual planet formation via core accretion. The planet continues to accrete until it becomes massive enough to isolate itself from the accretion flow via gap opening. The process repeats with a new pebble ring gathering at the new pressure maximum associated with the retreating dead-zone boundary. I discuss the theory’s predictions for planetary masses, relative mass scalings with orbital radius, and minimum orbital separations, and their comparison with observed systems. Finally I speculate about potential causes of diversity of planetary system architectures, i.e. STIPs versus Solar System analogs.


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Angela Adamo

Department of Astronomy
Stockholm University and Oskar Klein Centre
SE-10691 Stockholm - Sweden
tel: +46 (0)8 5537 8556
email: angela.adamo at astro.su.se<mailto:angela.adamo at astro.su.se>
http://ttt.astro.su.se/~adamo
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