Eric Feigelson Penn State University ONC/Paradigm for Star Formation STScI Oct 2013

1. 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

2. 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

3. 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

4. Complexity on many scales 1 pc 20 pc Orion Molecular Cloud complex (IRAS 60mm, left) + molecular filament in Ori A (SCUBA 850 mm, right)

5. 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

6. Chandra Orion Ultradeep Project All pre-main sequence stars are seen in X-rays

7. COUP: The Movie PMS stars exhibit high levels of magnetic flaring COUP: 22 papers Feigelson, Getman, et al. (2005-07)

8. 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.

9. 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

10. The MYStIX Sample

11. 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

12. X-ray `color-magnitude’ diagram MPCM = MYStIX Probable Complex Member Black = MPCMs Green = AGNs Blue = Unclassified Red/Orange = Field stars AV = 20 mag

13. The UKIRT Data UKIDSS pipeline improved with smaller apertures and higher sensitivity King, Naylor et al. 2013

14. 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

15. k Black = field stars Red = MIRES (MYStIX IR excess sources) Green = disk-free MPCMs Povich et al 2013

16. MPCMs: MYStIX Probable Complex Members Yellow = X-ray selected Red = MIRES Cyan = Published OB Broos et al. 2013

17. 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

18. 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

19. ONC region modeled as multiple subclustersCore-halo structure Stellar Sample Residual map after removal of iso- thermal ellipsoids

20. (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]

21. 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

22. “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)

23. 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

24. 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

25. 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)

26. 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

27. Eagle Nebula No mass segregation Kuhn et al., in prep

28. 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