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The ONC and the MYStIX Survey Massive Young Star-Forming Complex Study in Infrared and X-ray. Eric Feigelson Penn State University ONC/Paradigm for Star Formation STScI Oct 2013 . Outline. Introduction: Orion as a template for rich young clusters

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eric feigelson penn state university onc paradigm for star formation stsci oct 2013

The ONC and the MYStIX Survey

Massive Young Star-Forming Complex Study

in Infrared and X-ray

Eric Feigelson

Penn State University

ONC/Paradigm for Star Formation

STScI Oct 2013

outline
Outline
  • Introduction: Orion as a template for rich young clusters
  • The MYStIX Project … a very quick introduction
  • Comparison of ONC with other clusters

Conclusion

ONC is a good template for young stellar clusters

slide3

The Orion Nebula: Nearest massive star forming region

Becklin-Neugebauer

Small cluster of protostars

Orion Nebula Cluster

OB-dominated star cluster

age ~1-2 Myr

Protoplanetary disks

around Orion stars

slide4

Complexity on many scales

1 pc

20 pc

Orion Molecular Cloud complex (IRAS 60mm, left)

+ molecular filament in Ori A (SCUBA 850 mm, right)

slide5

Multiple star clusters with

age gradient

Orion Extended Nebula

in X-rays

0 Myr

1-2 Myr

4-5 Myr

Guedel et al. 2008

Alves & Bouy 2012

slide6

Chandra Orion Ultradeep Project

All pre-main sequence stars are seen in X-rays

slide7

COUP: The Movie

PMS stars exhibit high levels of magnetic flaring

COUP: 22 papers Feigelson, Getman, et al. (2005-07)

slide8

The X-ray Perspective

During the Chandra mission, we increasingly realized

that X-ray images were useful for improving the census of young stellar populations.

Chandra resolution and FOV is most effective for star forming regions at 0.5<d<3 kpc. AV~0-20 is not a problem, and penetration to AV~200 is possible.

X-ray selection complements more common Ha and infrared-excess selection for PMS stars. Together they give Class I-II-III populations.

mystix
MYStIX

Massive Young stellar complex

Study in Infrared and X-ray

Multiwavelength surveys of 20 massive star forming regions

Data analysis: 2009-12 Papers: 2013-15

Led at Penn State by Eric Feigelson & LeisaTownsley

with Michael Kuhn, KostantinGetman, Patrick Broos,

Matthew Povich, Heather Busk, Tim Naylor & others

Papers & electronic tables at

http://www.astro.psu.edu/mystix

the chandra data
The Chandra Data

Advanced data analysis gives X-ray source catalog with ~2x more sources than standard wavelet-based procedures. Light contamination (mostly quasars) is easily removed. Typical MYStIX target gives 500-3000 young stars.

Kuhn et al. 2013a

Townsley et al. 2013

slide12

X-ray `color-magnitude’

diagram

MPCM = MYStIX

Probable Complex Member

Black = MPCMs

Green = AGNs

Blue = Unclassified

Red/Orange = Field stars

AV = 20 mag

the ukirt data
The UKIRT Data

UKIDSS pipeline improved with smaller apertures and higher sensitivity

King, Naylor et al. 2013

the spitzer data
The Spitzer Data

3.6 um 8.0 um

Difficult to detect stars in nebulosity

Crowding: lower resolution than UKIRT or Chandra

Field star contami-nation can be bad!

Sensitivity is spatially inhomogeous

Kuhn et al. 2013b

W 40

NGC

2264

slide15
k

Black = field stars

Red = MIRES (MYStIX IR excess sources)

Green = disk-free MPCMs

Povich et al 2013

slide16

MPCMs: MYStIX Probable Complex Members

Yellow = X-ray selected

Red = MIRES

Cyan = Published OB

Broos et al.

2013

relative sizes of some mystix clusters
Relative sizes of some MYStIX Clusters

Trifid

NGC 6334

ONC

Greater Carina Nebula

Tr 15

NGC 6357

Tr 14

W40

Tr 16

NGC 2264

South

Pillars

Eagle

30 pc

finite mixture model
Finite Mixture Model
  • Cluster properties determined through maximum likelihood parameter estimation
  • Number of clusters determined with penalized likelihood criterion (AIC)
  • Membership determined using posteriors of fitted models

Cluster 1

Unclustered component

Kuhn et al. 2013a

Cluster 2

onc region modeled as multiple subclusters core halo structure
ONC region modeled as multiple subclustersCore-halo structure

Stellar

Sample

Residual

map after

removal

of iso-

thermal

ellipsoids

sub cluster sizes
(Sub)Cluster Sizes
  • Our sample:
  • Mean ~ 0.18 pc
  • SD ~ 0.4 dex

24

16

ONC

Number of Clusters

Similar to core size of ONC, found by Hillenbrand & Hartmann (1998).

Similar to width of molecular filaments found by André et al. (2010).

8

0

-1.5

-1.0

-0.5

0.0

log Core Radius [pc]

slide21

Central Core Density vs. Core Radius

The ONC is denser than most OB-dominated clusters

but not as dense as smaller clusters

ONC

Kuhn et al. 2013b, see Pfalzner 2009, 2012

slide22

“We seem to be getting a picture of star forming regions with multiple non-coeval subclusters that probably formed with roughly the same physical size, but have expanded like the clusters studied by Pfalzner.” Mike Kuhn

In Orion, these non-coeval subclusters are

(from north to south):

t~ 0.1 Myr OMC 4-3-2, OMC-1 (BN-KL), OMC-1S

t~ 1.2 Myr ONC core

t~ 2.0 Myr ONC halo

t~ 4-5 Myr NGC 1980 (Alves & Buoy 2012)

a new age estimate for young stellar clusters
A new age estimate for young stellar clusters

Traditional optical HR diagram are restricted to low-AV stars, and infrared disk classes or fractions are poorly calibrated.

AgeJXis a new age estimator based on an established empirical calibration between X-ray luminosity and mass  combine with MJ  unique location on evolutionary tracks  age. Individual

AgeJXvalues are still very uncertain, but median within MYStIXsubclusters give low spread.

Careful sample selection: strong X-ray, reliable near-IR photometry, median cluster age estimates

Getman et al. 2013

slide24

Age estimates averaged over MYStIX fields

Youngest:

W 40

Flame Nebula

RCW 38

ONC:

In the middle

Oldest:

NGC 2362

Carina (mixed)

Rosette (mixed)

ONC

5 Myr

0.5 Myr

Getman et al. 2013a

slide25

Intracluster age gradient seen in ONC and Flame Nebula cluster

Halos have older stars than cores

Result for PMS stars, unrelated to mass segregation

ONC AgeJX sample

ONC median AgeJX in radial bins

Getman et al. 2013b

(tentatively reported by Reggiani et al 2011)

emark a diagnostic summary function for spatial dependence of a mark variable orion nebula cluster
Emark: A diagnostic summary function for spatial dependence of a mark variable Orion Nebula Cluster

Large values indicate strong mass segregation

Mean mass

(null hypothesis)

pc

<log mass> [Mo]

99% confidence envelope from bootstrap simulations

pc

r (parsecs)

Kuhn et al., in prep

slide27

Eagle Nebula

No mass segregation

Kuhn et al., in prep

conclusion onc is a good template for clustered star formation
ConclusionONC is a good template for clustered star formation
  • Typical isothermal ellipsoid structure
  • Typical core radius
  • Higher than usual density (but on cluster expansion locus)
  • Typical age for clusters ionizing giant HII regions
  • Part of typical SF region age gradient (~10 pc scale)
  • ?Typical? intracluster age gradient (halo forms first)
  • Typical (but not ubiquitous) mass segregation