Most meteorites formed in the earliest moments

1
Most meteorites formed in the earliest moments of
solar system history Early solar system
consisted of a planetary nebula-- dust and gas
surrounding protostar and early sun Chondrites
components clearly formed in nebula. Differentiate
d bodies too?
Chondrites their components
Differentiated bodies
2
We see evidence for planet-forming nebular disks
around stars These disks occur around Young
Stellar Objects (YSOs)
Dusty cocoon surrounding YSO
3
Different types of YSOs 1) IR stars 2)
Proplyds 3) Herbig-Haro objects 4) T-Tauri
stars 5) Beta Pictoris systems Range from
protostars to newly-formed stars
4

• IR stars
• infrared protostars
• show excess emission in IR compared to visible
  wavelengths
• explained by dust cocoons surrounding protostar
• these cocoons obscure the visible light from the
  central star-like object, but are warmed by that
  visible light and so radiate in the IR

5
IR stars in Orion
visible light image
IR light image mosaic
6
IR star DC303.8-14.2
visible light (700 nm), showing dust
IR light (1.65 um), showing ring of warmed dust
around embedded IR star
IR light (2.17 um), showing inner clumps (shocked
gas?)
7

• Proplyds protoplanetary disks
• dusty cocoons seen around YSOs
• first seen clearly in the Orion Nebula

8
Proplyd with evidence for infalling matter
(nebular disk shocks)
Disk 800 AU across
Pattern of methanol emission can be explained by
clumpy accretion onto surface of disk
9

• Herbig-Haro
• Objects
• YSOs with
• disks bipolar
• outflows

10
Bipolar jet
11

• T-Tauri star
• catchall term for many types of YSOs
• YSO has not yet ignited H it follows Hayashi
  track in luminosity temperature
• YSO can show evidence for rapid rotation, strong
  magnetic field, strong stellar winds, short-lived
  brightness spikes (FU-Orionis outbursts), excess
  IR emission

H-R diagram showing Hayashi track (4-7) and Main
Sequence trend (grey band)
http//www.go.ednet.ns.ca/larry/stars/prtostar.ht
ml
12

• Beta Pictoris-type system
• newly-formed star that still has a surrounding
  dust disk
• YSO has achieved H to He fusion and falls on
  Main
• Sequence trend
• dust disk soon to be destroyed, either by
• stellar winds (material blown out of system)
• or
• movement to star (e.g., via Poynting-Robertson
  effect)
• new idea some Beta Pictoris-type dust disks may
  be
• regenerated by collisions between planets

13
Dust disk around Beta Pictoris seen edge on
colors represent light intensities
waves in disk probably
caused by interaction with planets
14
(No Transcript)