1. Randolf Klein SOFIA – USRA/NASA Ames July 2014 AASTCS 4: Workshop on Dense Cores - Monterey, CA Issues with SED Fitting, PMS Tracks, and the Birthline Exemplified with two Cores near IRAS 05345+3157

2. OVERVIEW July 2014WORKSHOP ON DENSE CORES - MONTEREY 2 How do massive stars form? Monolithic collapse and disk accretion, competitive accretion and runaway growth, or stellar collisions and mergers. (Zinnecker & Yorke 2007) Knowing the initial conditions of massive star formation would help to answer that question. Thus, I want to study: Can we identify a similar classification like Class0 to Class II for massive stars? How do massive cores/clumps and their SEDs evolve? Extrapolate to the earliest stages But first I get my tools ready while studying two intermediate mass protostars.

3. IRAS 05345+3157 Infrared cluster with shell Two massive cores detected in mm-survey (Klein et al. 2005) Large separation from IRAS source  MIPS observations (saturation) Pilot study to analyze SEDs of mm-cores and their evolution THE MASSIVE CORES IN IRAS 05345+3157 July 2014WORKSHOP ON DENSE CORES - MONTEREY 3

4. Green fuzzies (extended IRAC 4.5µm emission) Shocked gas? (cf. De Buizer&Vacca 2010) CARMA observations: CS 2-1 Infall signatures (Lee et al. 2011) Outflow (Fontani et al. 2009) PROTOSTELLAR CORES? July 2014WORKSHOP ON DENSE CORES - MONTEREY 4

5. SED FITTING (ROBITAILLE MODELS) Northern Core M ★ =8.0M  R ★ =30R  T ★ =5800K R env =86000AU M env =180M  L tot =910L  A V =260mag Age 5.6 10 4 yr Best model: 3007730 July 2014WORKSHOP ON DENSE CORES - MONTEREY 5

6. SED FITTING (ROBITAILLE MODELS) Southern Core M ★ =5.8M  R ★ =32R  T ★ =4300K R env =48000AU M env =110M  L tot =320L  A V =430mag Age: 1.2 10 4 yr Best model: 3003596 But these are not protostars! July 2014WORKSHOP ON DENSE CORES - MONTEREY 6

7. THE ROBITAILLE MODELS YSO Grid by T. Robitaille et al (2007, ApJS, 169, 328): 20,000 Env.-Disk-Models with 14 parameters 10 inclination angles: 200,000 SEDs On-line access and fitting Widely used to fit and interpret SEDs. But don’t just use the best fit. Online Fitter returns 1000 best matches, which allows to estimate uncertainties and significances. I considered a fit good when χ 2 -χ 2 best < 5/ data point leading to a range of good parameters July 2014WORKSHOP ON DENSE CORES - MONTEREY 7

8. THE ROBITAILLE MODELS A-priory selection 100L ☉ 0.1M  : 1456 models Statistical test if parameter distribution for a-priory and good model differs. Colored lines indicate that the fitted parameter distribution differs from the a-priory distribution. (All not listed parameters have the a-priory distribution except for the cavity angle) Northern Core with interquartile range M ★ =8.0M  7.5...8.0 R ★ =30R  32…42 T ★ =5800K4300…4600 R env =86000AU 54000…94000 M env =180M  130…250 L tot =910L  660…720 A V =260mag160…230 Age 56000yr 7800…26000 July 2014WORKSHOP ON DENSE CORES - MONTEREY 8

9. EVOLUTIONARY TRACKS Robitaille’s model grid was populated by randomly picking a mass and an age. Theoretical pre- main sequence tracks from Siess et al. 2000 and Bernasconi & Maeder 1996 were used to set the temperature and stellar radius accordingly. Evolutionary tracks from 7.0 to 0.1M for a solar metallicity. Dashed isochrones at 10 6, 10 7 and 10 8. Siess et al. 2000 July 2014WORKSHOP ON DENSE CORES - MONTEREY 9

10. THE BIRTHLINE Observational: upper envelope in the HR-diagram for pre-MS-stars Theoretical: locus of pre-MS-stars with protostellar radii HR diagram with visible stars driving molecular outflows: Open circles – HAeBe Filled circles – associated with CO Theoretical birthline Zero age main sequence Pre-MS tracks with mass What about PMS tracks above the birthline? “The Formation of Stars” Stahler & Palla 2004 Wiley-VHC July 2014WORKSHOP ON DENSE CORES - MONTEREY 10

11. THE PROBLEM The protostar evolves along the birthline while accreting: A.PS contracts B.Central D-burning C.PS contracts despite D- burning D.Radiative core D-burning in shell E.Completely radiative F.CNO-cycle creates convective core; PS joins MS When the accretion stops, the evolution follows the PMS tracks. Pre-main-sequence tracks above the birthline are unphysical. Star formation with disc accretion and rotation Birthline and PMS-tracks - Haemmerlé et al (2013): July 2014WORKSHOP ON DENSE CORES - MONTEREY 11

12. PROTOSTAR AS CENTRAL SOURCE Replace the PMS star with a protostar emitting the same luminosity and recalculate the SED (Whitney, B. A. et al. 2003) L ★ =910L  T ★ =5800K  8900K R ★ =30R   13R  Still a good fit as all the emission is reprocessed. Same for the southern core. July 2014WORKSHOP ON DENSE CORES - MONTEREY 12

13. WHICH BIRTHLINE? Location of the birthline depends on the accretion rate Hosokawa & Omukai (2009) assume a constant accretion rate. In blue: Haemmerle et al. (2013) use an empirical relation Ṁ acc (L) resulting in Ṁ acc = 10 -5...10 -3 M  yr -1 July 2014WORKSHOP ON DENSE CORES - MONTEREY 13

14. CONCLUSIONS The cores in IRAS 05345+3157 harbor intermediate-mass protostars. Infall signatures Deeply embedded heating source Outflows The SED is not sensitive to the central source (or disk) for such deeply embedded sources. Lessons learned: The central source in Robitaille’s modes and elsewhere where pre-MS- tracks are used may be unphysical. The radii are too large and thus the temperature too low for a given luminosity. The effect on the SED-fit? The total luminosity of the protostar gets reprocessed in the envelope. The emerging spectrum mainly depends on the luminosity. Outlook: study more envelopes. July 2014WORKSHOP ON DENSE CORES - MONTEREY 14

15. OUTLOOK Study candidates for very young, massive, star-forming cores Selection criteria: No radio, IRAS, MIR, NIR sources within 10” of the core’s peak. Minimum mass of 100 M ☉. Single-dish mm continuum surveys: Faundez et al. (2004): CS sources from Bronfman et al. (1996) Fulfill the IRAS UC HII region color criterion. Sridharan et al. (2005): High-mass protostellar objects (HMPO) from the survey by Beuther et al. (2002) excluding cores associated with masers. Klein et al. (2005): FIR bright IRAS sources (F(100µm)>500Jy) in the outer Galaxy Beltran et al (2006): Uses source sample from Palla et al. (1991), which used an IRAS color criterion for compact molecular clouds and excluded HII regions. July 2014WORKSHOP ON DENSE CORES - MONTEREY 15

16. OUTLOOK Selected 173 cores in 117 regions Compile SED from GLIMPSE, MIPS, HiGal and mm-surveys July 2014WORKSHOP ON DENSE CORES - MONTEREY 16

17. OUTLOOK And from SOFIA July 2014WORKSHOP ON DENSE CORES - MONTEREY 17