SAO: The Chandra Carina Complex Project

[bystander]

The Chandra Carina Complex Project
Smithsonian Astrophysical Observatory
Weekly Science Update | 2011 May 13

A false-color image of the X-ray emission from the massive cluster of hot young stars around the Eta Carinae Nebula. In addition to thousands of points corresponding to hot stars, the image shows that hot gas is widely distributed. The three colors correspond to three energy bands of X-rays, as labeled in the caption. Notation on the frame edges provides the sky location. (Credit: Chandra X-ray Observatory)

---

The Great Nebula in the constellation of Carina is a massive star-forming complex located about 7.5 thousand light-years away. The main star in the complex, Eta Carinae, shines brightly in the southern sky. Its ensemble of stellar clusters are young and hot, with ages that range from less than about one million years to about six million years. Altogether, the region contains one of the richest concentrations of massive young stars in the galaxy. In addition, the region is rich in non-stellar material including filaments, pillars, cavities, arcs, and other features indicative of a turbulent and complex history.

The Nebula is not only rich in hot sources. It is also full of mysteries because the numerous complex structures have proven difficult to explain. Some scientists think there has been an early epoch of active star formation in the region, and whether or not a supernova may have gone off in the neighborhood (and so generated some of the observed structures) is actively debated. The role of intense shocks and colliding winds in generating the hot diffuse gas that is seen is also controversial.

A large team of CfA astronomers and their colleagues has used the Chandra X-ray Observatory to study the Great Nebula in Carinae, integrating new data with older observations from the Chandra archives. They have begun publishing a landmark set of sixteen papers on the region and its rich astrophysical contents, including separate studies of its massive stars, intermediate mass stars, and low mass stars, magnetic field effects, and the infrared characteristics of its dust enshrouded sources.

One of the new papers examines the X-ray emission from the hottest, most massive stars in the cluster, of which 68 (of the 70 known) were detected in this study. It has long been thought that shocks from powerful winds produce X-ray emission; this is in contrast to smaller stars whose photospheres can produce X-ray emission. This new study finds that there appear to be at least three different kinds of shocks at work: those embedded in the stellar wind, others due to collisions between the winds from two massive stars that orbit each other in a binary pair, and shocks produced when magnetically channeled winds from the opposite hemispheres of a star meet and collide. Other results of this survey include a catalog of over 14,000 X-ray point sources, mostly stars. The set of new papers represents a basic reference for understanding this famous beacon in the southern sky and the mechanisms at work generating stellar X-rays.

The Chandra Carina Complex Project (CCCP):
A Special Issue of The Astrophysical Journal Supplement Series
(Volume 194, Number 1, May 2011)

1. An Introduction to the Chandra Carina Complex Project - LK Townsley et al
   • DOI: 10.1088/0067-0049/194/1/1 | arXiv:1102.4779
2. A Catalog of Chandra X-ray sources in the Carina Nebula - PS Broos et al
   • DOI: 10.1088/0067-0049/194/1/2 | arXiv:1102.5121
3. Source Contamination in X-ray Studies of Star-forming Regions: Application to the Chandra Carina Complex Project - KV Getman et al
   • DOI: 10.1088/0067-0049/194/1/3 | arXiv:1102.5122
4. A Naive Bayes Source Classifier for X-ray Sources - PS Broos et al
   • DOI: 10.1088/0067-0049/194/1/4 | arXiv:1102.5120
5. Carina OB Stars: X-ray Signatures of Wind Shocks and Magnetic Fields - M Gagné et al
   • DOI: 10.1088/0067-0049/194/1/5 | arXiv:1103.1149
6. Candidate X-ray-emitting OB Stars in the Carina Nebula Identified Via Infrared Spectral Energy Distributions - MS Povich et al
   • DOI: 10.1088/0067-0049/194/1/6 | arXiv:1102.5366
7. Global X-ray Properties of the O and B Stars in Carina - Y Nazé et al
   • DOI: 10.1088/0067-0049/194/1/7 | arXiv:1103.0101
8. X-ray Emission from the Double-binary OB-star System QZ Car (HD 93206) - ER Parkin et al
   • DOI: 10.1088/0067-0049/194/1/8 | arXiv:1103.0794
9. X-ray Star Clusters in the Carina Complex - ED Feigelson et al
   • DOI: 10.1088/0067-0049/194/1/9 | arXiv:1103.0802
10. Near-infrared Properties of the X-ray-emitting Young Stellar Objects in the Carina Nebula - T Preibisch et al
    • DOI: 10.1088/0067-0049/194/1/10 | arXiv:1103.2052
11. A Chandra ACIS Study of the Young Star Cluster Trumpler 15 in Carina and Correlation with Near-infrared Sources - J Wang et al
    • DOI: 10.1088/0067-0049/194/1/11 | arXiv:1103.0785
12. The Chandra Carina Complex Project View of Trumpler 16 - SJ Wolk et al
    • DOI: 10.1088/0067-0049/194/1/12 | arXiv:1103.1126
13. The Search for Low-mass Companions of B Stars in the Carina Nebula Cluster Trumpler 16 - NR Evans et al
    • DOI: 10.1088/0067-0049/194/1/13 | arXiv:1103.1344
14. A Pan-Carina Young Stellar Object Catalog: Intermediate-mass Young Stellar Objects
    in the Carina Nebula Identified Via Mid-infrared Excess Emission - MS Povich et al
    • DOI: 10.1088/0067-0049/194/1/14 | arXiv:1103.2060
15. The Chandra Carina Complex Project: Deciphering the Enigma of Carina's Diffuse X-ray Emission - LK Townsley et al
    • DOI: 10.1088/0067-0049/194/1/15 | arXiv:1103.0764
16. The Integrated Diffuse X-ray Emission of the Carina Nebula Compared to Other Massive Star-forming Regions - LK Townsley et al
    • DOI: 10.1088/0067-0049/194/1/16 | arXiv:1103.1606

<< Previous Science Update

[bystander]

Carina Nebula: Nearby Supernova Factory Ramps Up
Chandra X-ray Observatory | 2011 May 24

DSS Optical Image of the Carina Nebula
(Credit: Digitized Sky Survey)

Chandra X-ray Image of the Carina Nebula
(Credit: NASA/CXC/PSU/L.Townsley et al)

This large Chandra image shows the Carina Nebula, a star-forming region in the Sagittarius-Carina arm of the Milky Way a mere 7,500 light years from Earth. Chandra's sharp X-ray vision has detected over 14,000 stars in this region, revealed a diffuse X-ray glow, and provided strong evidence that massive stars have already self-destructed in this nearby supernova factory.

The lower energy X-rays in this image are red, the medium energy X- rays are green, and the highest energy X-rays are blue. The Chandra survey has a large field of 1.4 square degrees, made of a mosaic of 22 individual Chandra pointings. In total, this image represents 1.2 million seconds -- or nearly two weeks -- of Chandra observing time. A great deal of multi-wavelength data has been used in combination with this new Chandra campaign, including infrared observations from the Spitzer Space Telescope and the Very Large Telescope (VLT).

Several pieces of evidence support the idea that supernova production has already begun in this star-forming region. Firstly, there is an observed deficit of bright X-ray sources in Trumpler 15, suggesting that some of the massive stars in this cluster were already destroyed in supernova explosions. Trumpler 15 is located in the northern part of the image, as shown in a labeled version (see right), and is one of ten star clusters in the Carina complex. Several other well known clusters are shown in the labeled image .

The detection of six possible neutron stars, the dense cores often left behind after stars explode in supernovas, provides additional evidence that supernova activity is ramping up in Carina. Previous observations had only detected one neutron star in Carina. These six neutron star candidates are too faint to be easily picked out in this large-scale image of Carina.

The diffuse emission observed by Chandra also supports the idea that supernovas have already erupted in Carina. Some of the diffuse X-ray emission almost certainly comes from the winds of massive stars, but some may also come from the remains of supernova explosions.

Finally, a new population of young massive stars has been detected in Carina, potentially doubling the number of known young, massive stars that are mostly destined to be destroyed later in supernova explosions. These stars are seen as bright X-ray sources scattered across the image. Also shown in the labeled image is the most famous member of the Carina Nebula, Eta Carinae, a massive, unstable star that may be on the verge of exploding as a supernova. These latest results suggest Eta Carinae is not alone in its volatility within the Carina Nebula.

Press Release

New View of the Great Nebula in Carina
NASA JPL-Caltech Spitzer | 2011 May 24

Credit: NASA/JPL-Caltech/M. Povich (Penn State Univ)

---

Eta Carinae is one of the most massive and brightest stars in the Milky Way. Compared to our own Sun, it is about 100 times as massive and a million times as bright. This famed variable hypergiant star (upper center) is surrounded by the Carina Nebula. In this composite image spanning the visible and infrared parts of the spectrum, areas that appear blue are not obscured by dust, while areas that appear red are hidden behind dark clouds of dust in visible light. A study combining X-ray and Infrared observations has revealed a new population of massive stars lurking in regions of the nebula that are highly obscured by dust. Adding these new massive stars to the known massive stars suggests that the Carina Nebula will produce twice as many supernova explosions as previously supposed.

Visible light in the blue part of the spectrum from the Digital Sky Survey is represented as blue, near infrared light with a wavelength of 2.2 microns from the Two Micron All Sky Survey (2MASS) is green, and infrared observations from the Infrared Array Camera on NASA's Spitzer Space telescope at 3.6 microns is red.