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Chandra Observations of the Massive Stellar Cluster Trumpler 14 in Carina

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Chandra Observations of the Massive Stellar Cluster Trumpler 14 in Carina Chandra Observations of the Massive Stellar Cluster Trumpler 14 in Carina Leisa Townsley, Patrick Broos, Eric Feigelson Penn State University THE GREAT NEBULA IN CARINA * D = 2.8 kpc (Tapia et al. 2003, MNRAS 339, 44); 10’ ~8.1pc. Age ~1 Myr. X-RAYS FROM YOUNG STARS * Trumpler 14 (Tr14): a very rich cluster on the edge of the giant mo- OUR CHANDRA OBSERVATION * Aimpoint on HD 93129AB, Tr14’s central O2I -- lecular cloud Carina I, which contains several embedded IR sources. -59:25:00 O3V binary. Chandra detects 31 of the 37 O and * Tr14 contains at least 30 O and early-B stars, including an O2 star; Tr14 in Carina, 57-ksec ACIS-I: early-B stars in the ACIS FoV. evolved Wolf-Rayet stars are nearby (so maybe supernovae). 350--790 eV; 790--970 eV; * We find ~1600 point sources suffused by soft, * The massive young cluster Tr16, containing Eta Carinae, lies ~15’ SE of 970--1650~eV ; -59:30:00 bright diffuse emission. Tr14. The Carina complex contains at least 10 more young clusters. csmooth. * Based on other studies (e.g. Getman et al. 2005, APJS 160, * Images below are shown in Galactic coordinates to emphasize the 353) we expect only ~10% contamination from Carina superbubble. -59:35:00 foreground stars and background AGN. * This increases the number of known members of Tr14 and Tr16 by a factor of several and pro- -59:40:00 vides many identifications of pre-main se- quence members. 45:00.0 30.0 10:44:00.0 30.0 43:00.0 42:30.0 -59:32:30 40.0 HD 93129A 50.0 HD 93129B 2° × 1.8° visual image from N. 2° × 1.8° mid-IR image from MSX -59:33:00 Smith et al. 2000 (ApJ 532, L145): (MSX/IPAC/NASA): 8.28µm, 12.13µm, OIII, Hα, SII. 14.65µm. 10.0 - 0.40 ACIS-I aimpoint: 0.5--2 keV; 2--7 keV 20.0 10:44:00.0 58.0 56.0 10:43:54.0 287.5 287.4 287.3 EARLY O STAR SPECTRA -0.60 The earliest O stars in Tr14 were fit in XSPEC with thermal plasmas, wabs(vapec + vapec) or wabs(apec). Lx,corr is the full-band (0.5--8 keV) X-ray luminosity corrected for absorption. Smoothed Tr14 Diffuse HD 93129A HD 93129B -0.70 full-band L = 1.4×10³³ ergs/s x‚corr Lx‚corr = 0.2×10³³ ergs/s (0.5--7 keV) NH = 4×10²¹ cm-² NH = 2×10²¹ cm-² ACIS-I image of Tr14; dif- -0.80 fuse extrac- S3 Diffuse tion regions kT=0.6 keV kT=2.6 keV kT=0.5 keV 28' × 28' 2MASS image -0.90 of Tr16 and Tr14. marked. DIFFUSE X-RAY EMISSION INTERPRETATION * Point sources were extracted and masked using ACIS Extract HD 93250 HD 93128 * A modest Chandra/ACIS-I exposure of Tr14 in Carina reveals 1600 point L = 2.1×10³³ ergs/s x‚corr Lx‚corr = 0.1×10³³ ergs/s (www.astro.psu.edu/xray/docs/TARA/ae_users_guide.html); see poster by Patrick Broos. NH = 1×10²¹ cm-² sources, mostly members of the Tr14 and Tr16 massive stellar clusters. NH = 6×10²¹ cm-² * Diffuse regions and backgrounds were defined with SAOImage DS9. * Diffuse spectra were extracted using ACIS Extract, fit with XSPEC: wabs(apec+apec) for Tr14 dif- fuse, vapec (no absorption) for S3 diffuse. * HD 93129AB, a very early-type binary at the heart of Tr14, is resolved * Lx,corr and Sx,corr are the soft-band (0.5--2 keV) absorption-corrected X-ray luminosity and X-ray surface brightness, respectively. and the components are shown to possess very different X-ray spectra. Tr14 Diffuse L = 3.0×10³³ ergs/s kT=0.3 keV x‚corr Other O stars in the field show a similar mix of soft and hard spectra. kT=0.6 keV kT=3.3 keV Sx‚corr = 2.0×10³² ergs/s/pc-² NH = 0.7×10²¹ cm-² Tr14 Bkgd Hard emission may be due to colliding winds in yet-to-be-discovered -59:25:00 close binary systems or to complex magnetic field interactions. 30:00 kT=0.26 keV kT=0.62 keV * Soft diffuse X-ray emission pervades the Tr14 H II region and is resolved * HD 93129A, the prototype O2 If* star (Walborn et al. 2002, AJ 123, 2754) was from the point source population; it is most likely from the fast O-star 35:00 recently resolved into a 55-mas double (Nelan et al. 2004, AJ 128, 323). winds that thermalize and shock the surrounding media, although its * The hard X-ray component seen in its ACIS spectrum, along with S3 Diffuse Lx‚corr = 1.8×10³³ ergs/s spatial distribution is mysterious. -59:40:00 its high Lx and high abundances, suggests that HD 93129A may Sx‚corr = 1.3×10³² ergs/s/pc-² Tr14 Diffuse NH = 0 cm-² S3 Bkgd be a colliding-wind binary (Portegies Zwart, Pooley, & Lewin 2002, ApJ 574, 762). * We also see soft, bright diffuse emission requiring enhanced Ne and Fe 45:00 * Comparing its spectrum and Lx to HD 93250 above suggests kT=0.58 keV on the S2 and S3 off-axis CCDs, far from any of Carina’s massive stellar abund=0.3Zsol except that HD 93250 may also be a colliding-wind binary. Ne = 0.6, Fe = 0.7 clusters. This emission may be from a ``cavity’’ supernova remnant that -59:50:00 * An alternative explanation for the hard X-ray emission might be S3 Diffuse (e.g. Chu et al. 1993, ApJ 414, 213) exploded inside the Carina superbubble . magnetically-confined wind shocks (e.g. Stelzer et al. 2005, ApJS 160, 557), but 45:00.0 10:44:00.0 43:00.0 42:00.0 HD 93129A at least is known to be more than one star. * Diffuse emission in Tr14 not cospatial with the cluster’s stars!? * In contrast, HD 93129B and HD 93128 show soft X-ray spectra Support provided by Chandra X-ray Observatory grant GO4-5006X. * S3 emission appears brighter but has smaller intrinsic Lx, Sx. more typical of single O stars and are much fainter. .
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