1 / 9

Wayne G. Roberge & Raymond L. Menzel NY Center for Astrobiology (NYCA)

Electrodynamic Heating in Protoplanetary Disks. Wayne G. Roberge & Raymond L. Menzel NY Center for Astrobiology (NYCA) Rensselaer Polytechnic Institute. Motivation. Chondritic meteorites deliver amino acids to Earth. Chondrites are fragments of C-type asteroids.

alda
Télécharger la présentation

Wayne G. Roberge & Raymond L. Menzel NY Center for Astrobiology (NYCA)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Electrodynamic Heating in Protoplanetary Disks Wayne G. Roberge & Raymond L. Menzel NY Center for Astrobiology (NYCA) Rensselaer Polytechnic Institute

  2. Motivation • Chondritic meteorites deliver amino acids to Earth. • Chondrites are fragments of C-type asteroids. • Were prebiotics synthesized on C asteroids? • They were warm and wet! But why? What heated asteroids and how prevalent is this process in protoplanetary disks?

  3. Asteroid Composition Types Igneous (SME) - melting; partially or completely exposed metallic cores. Metamorphic (CBGF) - aqueous alteration at 25-150 oC; hydrated minerals. Primitive (PD) – no heating; primitive solar system materials (?). Image: NASA/Hubble Space Science Institute (STScI). W.B. McKinnon, Nature, 340, 343 (1989)

  4. Radioactive Heating of Asteroids Urey 1955 • 26Al 26Mg + energy • Half life t1/2 = 0.7 Myr • 26Mg in meteorite Allende implies live 26Al was present. • 26Al/27Al = 6 x 10-5 in Allende, enough to melt asteroids. • But how did 26Al arrive at the party live? • Unknown but 26Al DID get here! • Why did heating decrease with heliocentric distance? • Only ~10-3 -10-2 of Sun-like stars receive live SLR (Ouellette et al. 2010).

  5. “Induction” Heating of Asteroids Sonnet et al. 1970 Ionized T Tauri Wind v0 =400 km/s E’ Plasma Frame: E=0, B=B0 Body frame: E’= -v0/c x B0 asteroid • Sonnet et al: Electric field E’ in asteroid frame. • Currents in plasma (yellow) flow from + to - . • Currents inside asteroid (green) close circuit. • Heating rate: P = J E = sE2 ~ 10-8 W/kg.

  6. Induction Heating Reexamined V0 here! What’s wrong with E’=-v0/c x B?

  7. Our Calculation

  8. Electric Field at Asteroid Surface In weakly inonized disks e << 1 and E ~ EH ~ v0B0/c!!!

  9. Conclusions • Classical induction heating invalid. • Found new “electrodynamic” mechanism. • Operates in weakly ionized disks! • Also operates in ionized disks. • At least as efficient as induction heating.

More Related