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. Differentiated bodies too? Chondrites & their componentsDifferentiated bodies

We see evidence for planet-forming nebular disks around stars These disks occur around Young Stellar Objects (YSOs) Dusty cocoon surrounding YSO

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

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

visible light imageIR light image mosaic IR stars in Orion

IR star DC 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?)

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

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

Herbig-Haro Objects: YSOs with disks & bipolar outflows

Bipolar jet

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)

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

colors represent light intensities waves in disk probably caused by interaction with planets Dust disk around Beta Pictoris seen edge on