Massive Star Feedback and Triggered Star Formation: Confronting multi-wavelength observations of the Carina Nebula with numerical simulations
Zusammenfassung der Projektergebnisse
The Carina Nebula (CN) is a unique target for detailed studies of violent massive star formation and the resulting feedback effects of cloud dispersal and triggered star formation. In this project, we have obtained and analyzed a comprehensive set of new wide-field multi-wavelength (sub-mm to X- ray) observations of the CN, that allowed a detailed characterization of the cloud structure as well as the properties of the young stellar populations. Some of these observational results have then been modeled by sophisticated numerical simulations, in order to get new insight into the underlying physical processes. The first step of our observations was a very deep near-infrared survey of the central Nebula region with HAWK-I at the ESO 8m Very Large Telescope. These data are sensitive enough to detect all young stars in the Carina Nebula down to masses of 0.1 M⊙ . However, due to the CN’s position very close to the Galactic plane, most of the more than 600 000 stars visible in these HAWK-I images are background field stars, unrelated to the Carina Nebula. To solve this contamination problem and identify the population of young stars in the CN, we have participated in the Chandra Carina Complex Project, in which the NASA X-ray satellite Chandra observed the CN for more than 17 full days and detected 14 368 individual X-ray sources. Since young stars are much stronger X-ray emitters than older field stars, such X-ray images provide an excellent tool to pick out the young stars among the large numbers of unrelated field stars. Our HAWK-I infrared data allowed us to identify the infrared counterparts of 90% of the X-ray sources in the common area, and we found that about 75% of the X-ray sources are young stars in the CN. This combination of X-ray and infrared data yielded, for the first time, a statistically complete sample of the young stellar population in the CN, and allowed us to determine the ages, masses, and protoplanetary disk properties of these stars. We have also combined all available mid-infrared (3.6−24 µm) Spitzer data into a wide-field (≈ 3 deg2 ) map and produced a photometric catalog of 569 773 mid-infrared sources. Our analysis of this catalog provided new insights into the size of the young stellar population and the clustering properties. In order to investigate the interaction of the stars and the surrounding clouds, we used our wide-field sub-mm map that we had obtained with the bolometer camera LABOCA at the APEX Telescope. This LABOCA map provided an unprecedented view of the cold, dense clouds in the CN at a very good spatial resolution of 0.2 pc. In the light of results from numerical simulations, we can assume that most of the pre-supernova damaging and shaping of clouds is done by the ionizing radiation from the massive stars. While stellar winds effectively disperse the immediate surrounding of the stellar feedback source, their impact quickly drops rapidly with distance from the source as they appear to have little direct impact on the cold gas. Stellar winds however contribute to expel the ionized gas from porous clouds. When it comes to the triggering of star formation, it appears quite difficult to pinpoint or infer the effects of massive star feedback on the molecular gas environment or on the stellar population from observations of a particular complex. While morphologies like pillars and shells are strongly indicative of the impact of the stellar feedback, it seems very difficult to identify sites of triggered star formation from observations of star forming regions. Simulations by Dale et al. show that triggering is a localized second order effect. There is a correlation between triggered objects and pillar and shell structures, but structures also host many stars that would have formed anyway due to initial density enhancements. Stellar winds might contribute to delay or even slightly reduce star formation. No simulations so far were able to reproduce the overall complexity of the Carina Nebula. Observational clues like the high temperatures inferred from X-ray Observations and the presence of the runaway star MJ 218 are hints that the ionizing radiation and stellar winds from massive stars are not enough to explain the complexity of the region. Although these feedback processes might be important for the evolution of some localized pillars and bubbles like Gum 31. The following results of this project have been reported in the media in the form of press/image releases: • 16.09.2011: European Southern Observatory Press/Image Release: The Cool Clouds of Carina: APEX gives us a new view of star formation in the Carina Nebula, (www.eso.org/public/news/eso1145/) • 08.02.2012: European Southern Observatory Press/Image Release: VLT Takes Most Detailed Infrared Image of the Carina Nebula, (www.eso.org/public/news/eso1208/) • 08.02.2012: LMU Presseinformation: Der Carina-Nebel im Rampenlicht: Bislang detailreichste Aufnahme der Sternkinderstube (www.uni-muenchen.de/aktuelles/presseinformationen/2012/f-09-12.html) These Press/Image Releases triggered numerous further reports, for example: www.weltderphysik.de/gebiet/astro/sterne/vermessung-des-carinanebels/ www.spiegel.de/wissenschaft/weltall/carinanebel-tiefe-einblicke-in-diesternenfabrik-a-814134.html www.bbc.co.uk/newsround/16943672 www.space.com/14501-space-photo-carina-nebula-infrared-stars.html www.astronomynow.com/news/n1202/08carina/ www.space.com/17833-the-cool-clouds-of-carina.html astrobites.org/2013/05/02/the-mystery-of-the-sickle-in-the-carina-nebula/ The Chandra Carina Complex Project and the role of our HAWK-I near-infrared survey for the identification of the X-ray sources were described in a NEWS & VIEWS article in the Journal Nature: www.nature.com/nature/journal/v475/n7357/full/475460a.html
Projektbezogene Publikationen (Auswahl)
- A deep widefield sub-mm survey of the Carina Nebula complex, Astronomy & Astrophysics, 525, A92 (2011)
Th. Preibisch, F. Schuller, H. Ohlendorf, S. Pekruhl, K.M. Menten, H. Zinnecker
- Deep wide-field near-infrared survey of the Carina Nebula, Astronomy & Astrophysics, 530, A34 (2011)
Th. Preibisch, Th. Ratzka, B. Kuderna, H. Ohlendorf, R.R. King, S. Hodgkin, M. Irwin, J.R. Lewis, M.J. McCaughrean, H. Zinnecker
- Detection of a large massive circumstellar disk around a high-mass young stellar object in the Carina Nebula, Astronomy & Astrophysics, 530, A40 (2011)
Th. Preibisch, T. Ratzka, T. Gehring, H. Ohlendorf, H. Zinnecker, R.R. King, M.J. McCaughrean, J.R. Lewis
- Near-Infrared properties of the X-ray emitting young stellar objects in the Carina Nebula, Astrophysical Journal Supplements, 194, 10 (2011)
Th. Preibisch, S. Hodgkin, M. Irwin, J.R. Lewis, R.R. King, M.J. McCaughrean, H. Zinnecker, L. Townsley, P. Broos
- Star Formation at High Resolution: Zooming into the Carina Nebula, the nearest laboratory of massive star feedback, invited chapter in the book series Reviews in Modern Astronomy Vol. 23: Zooming in: The Cosmos at High Resolution, ed. R. von Berlepsch, Wiley- VCH, Berlin, p. 223–236 (2011)
Th. Preibisch
- Jet-driving protostars identified from Spitzer observations of the Carina Nebula Complex, Astronomy & Astrophysics, 540, A81 (2012)
H. Ohlendorf, Th. Preibisch, B. Gaczkowski, Th. Ratzka, R. Grellmann, A. McLeod
- Discovering young stars in the Gum 31 region with infrared observations, Astronomy & Astrophysics, 552, A14 (2013)
H. Ohlendorf, Th. Preibisch, B. Gaczkowski, Th. Ratzka, J. Ngoumou, V. Roccatagliata, R. Grellmann
(Siehe online unter https://doi.org/10.1051/0004-6361/201220218) - The Clump Mass Function of the Dense Clouds in the Carina Nebula Complex, Astronomy & Astrophysics, 550, A29 (2013)
S. Pekruhl, Th. Preibisch, F. Schuller, K. Menten
(Siehe online unter https://doi.org/10.1051/0004-6361/201218815) - The mysterious Sickle Object in the Carina Nebula: A stellar wind induced bow shock grazing a clump?, Astrophysical Journal, 769, 139 (2013)
J. Ngoumou, Th. Preibisch, Th. Ratzka, A. Burkert
(Siehe online unter https://doi.org/10.1088/0004-637X/769/2/139)
