The All-Orion Spectroscopic Survey

and other Hecto Surveys of Pre-main Sequence Populations

James Muzerolle (for Lori Allen)

withTom Megeath, Elaine Winston, Luis Chavarria, Xavier Koenig, Gabor Furesz (CfA)Kevin Flaherty (UofA)Cesar Briceno, Jesus Hernandez (CIDA, Venezuela)

MIPS 24 Overview

Hecto ideal for characterizing large PMS populations

Hectospec:– large FOV allows efficient coverage of extended populations– wavelength coverage, resolution provides excellent spectral typing– youth diagnostics such as Li, Halpha

Hectochelle:– kinematics via radial velocities– stellar rotation velocities– accretion properties via Halpha profiles

provides powerful complement with Spitzer surveys

The All-Orion Spectroscopic Survey

Targeting thousands of young stars in the Orion GMC, selected from Spitzer and QUEST imaging surveys.

Orion region provides nearbylaboratory spanning a widevariety of environments, ages

(Complementary to Furesz et al. ONC survey)

OB 1a:~10 Myr, no gas

OB 1b: ~4 Myr, some gas

ONC (OB 1d):< 1Myr, gas

NGC 2068/2071

NGC 2024

Spectra: confirming membership

Li I 6707 Å important to distinguish WTTS from field dMe stars:

contamination is significant in wide-field surveys!

NGC 2068/2071

NGC 2068/2071

Active star formation in 3 subclusters

Spitzer results:• Class I protostars tightly confined in linear structures near dense gas • class II objects w/ disks more spread out• a few % of disks appear to be in transition, with optically thin inner regions

What are the characteristics of the stellar population?

• ages• masses• dynamics• accretion properties

Muzerolle et al. in preparation

NGC 2068/2071

Hectochelle and Hectospec

Spectral types, luminosities, masses, ages, radial velocities, rotational velocities, accretion rates.

Targets selected from SDSS optical CM diagram

NGC 2068/2071

HR diagram: ages ~1-3 Myr, masses ~0.2-1.5 Msun evidence for separate, 10 Myr-old population??

Flaherty et al. in prep.

NGC 2068/2071

disk fraction as a function of spectral type/mass

Similar to slightly older cluster IC 348 (Lada et al. 2005)

Characterizing the low-mass PMS population of Orion OB1: ages

Optical photometry + spectroscopy provide ages, masses

10

3

1

30

3

10

1

30

ZA

MS

ZA

MS

Siess et al. 2000

~4 Myr ~10 Myr

Characterizing the low-mass PMS population of Orion OB1: new groups

OB 1a

25 Orionis

The 25 Orionis stellar aggregate: a kinematically distinct, rich TW Hya

analogue

● 25 Ori: B1Ve● V346 Ori: Herbig Ae/Be● ~200 TTS

1

10

~ 8 Myr

Other star formation projects with Hectospec

Infrared and X-ray Properties of Young Stellar ClustersElaine Winston (University College Dublin) SAO pre-doc

(Tom Megeath, SAO advisor)

Photodissociation Regions in Massive Star Forming RegionsLuis Chavarria (University of Chile) SAO pre-doc

(Lori Allen, SAO advisor)

The Star Formation History of W5Xavier Koenig (Harvard University)(Lori Allen, advisor)

IRAC 4.5

MIPS 24

Hectospec+SpitzerFirst HR diagram of this region = Luminous (young?) 24-micron sources

d=2kpc

[Chavarria, Koenig & Allen 2006]

What is the star-forming history of W5 ?

[Koenig, Muzerolle & Allen 2006]

MIPS 24

results on distributed star formation in the L1641 cloudand massive star forming regions in the ONC & W5 on the way!

Serpens Class DistributionIRAC three colour mosaic of central core of cluster, blue: 3.6um, green: 4.5 um, red: 8.0um. (J2000.)

Showing distribution of sources with X-ray detections by class.

Class I: white circles

Flat Sp: blue invert. triangles

Class II: green triangles

Class III: red squares

Class not segregated – why?

Do the classes represent an evolution of the disk with age? If so, why are they mixed?

Is disk structure dependant on cluster environment, are they coeval? Why the mix of CI, FS, CII in the ‘V’ formation?

Clustering of CIII’s? Why not dispersed? Young?

Circles: Class I, Invert. Triangle: Flat Spectrum, Triangle: Class II

Square: Transistion Disks, Large Star: an X-ray detection

Small Asterisk: Not Classified (presumably Class III)

H-R Diagram of

Serpens Cloud

[Winston & Megeath 2006]