Department of Physics
Permanent URI for this collectionhttp://localhost:4000/handle/123456789/1932
Browse
5 results
Search Results
Item X-Ray Young Stars in the Carina Nebula(Protostars and Planets V Posters, 2005) Vaidya, KausharX-Ray Young Stars in the Carina Nebula - NASA/ADS Now on home page ads icon ads Enable full ADS view NASA/ADS X-Ray Young Stars in the Carina Nebula Sanchawala, K. ; Chen, W. -P. ; Lee, H. -T. ; Nakajima, Y. ; Tamura, M. ; Sato, S. ; Chu, Y. -H. Abstract Publication: Protostars and Planets V Posters Pub Date: 2005 Bibcode: 2005prpl.conf.8242S No Sources Found data products Chandra (1) © The SAO/NASA Astrophysics Data System adshelp[at]cfa.harvard.edu The ADS is operated by the Smithsonian Astrophysical Observatory under NASA Cooperative Agreement NNX16AC86A NASA logo Smithsonian logo Resources About ADS ADS Help What's New Careers@ADS Social @adsabs ADS Blog Project Switch to full ADS Is ADS down? (or is it just me...) Smithsonian Institution Smithsonian Privacy Notice Smithsonian Terms of Use Smithsonian Astrophysical Observatory NASAItem Optical spectroscopy of x-ray-selected young stars in the carina nebula(IOP, 2015-12) Vaidya, KausharWe present low-resolution optical spectra for 29 X-ray sources identified as either massive star candidates or low-mass pre-main-sequence (PMS) star candidates in the clusters Trumpler 16 and Trumpler 14 of the Carina Nebula. Spectra of two more objects (one with an X-ray counterpart, and one with no X-ray counterpart), not originally our targets, but found close (∼3'') to two of our targets, are presented as well. Twenty early-type stars, including an O8 star, seven B1–B2 stars, two B3 stars, a B5 star, and nine emission-line stars, are identified. Eleven T Tauri stars, including eight classical T Tauri stars (CTTSs) and three weak-lined T Tauri stars, are identified. The early-type stars in our sample are more reddened compared to the previously known OB stars of the region. The Chandra hardness ratios of our T Tauri stars are found to be consistent with the Chandra hardness ratios of T Tauri stars of the Orion Nebula Cluster. Most early-type stars are found to be nonvariable in X-ray emission, except the B2 star J104518.81–594217.9, the B3 star J104507.84–594134.0, and the Ae star J104424.76–594555.0, which are possible X-ray variables. J104452.20–594155.1, a CTTS, is among the brightest and the hardest X-ray sources in our sample, appears to be a variable, and shows a strong X-ray flare. The mean optical and near-infrared photometric variability in the V and Ks bands, of all sources, is found to be ∼0.04 and 0.05 mag, respectively. The T Tauri stars show significantly larger mean variation, ∼0.1 mag, in the Ks band. The addition of one O star and seven B1–B2 stars reported here contributes to an 11% increase of the known OB population in the observed field. The 11 T Tauri stars are the first ever confirmed low-mass PMS stars in the Carina Nebula region.Item A smoking gun in the carina nebula(IOP, 2009-03) Vaidya, KausharThe Carina Nebula is one of the youngest, most active sites of massive star formation in our Galaxy. In this nebula, we have discovered a bright X-ray source that has persisted for ∼30 years. The soft X-ray spectrum, consistent with kT ∼ 128 eV blackbody radiation with mild extinction, and no counterpart in the near- and mid-infrared wavelengths indicates that it is a ∼106 year old neutron star housed in the Carina Nebula. Current star formation theory does not suggest that the progenitors of the neutron star and massive stars in the Carina Nebula, in particular η Car, are coeval. This result suggests that the Carina Nebula experienced at least two major episodes of massive star formation. The neutron star may be responsible for remnants of high-energy activity seen in multiple wavelengths.Item The American Astronomical Society logo. The Institute of Physics logo. An X-Ray and Near-Infrared Study of Young Stars in the Carina Nebula(IOP, 2007) Vaidya, KausharWe present a multiwavelength study of the central region of the Carina Nebula, including Trumpler 16 and part of Trumpler 14. Our analysis of the Chandra X-Ray Observatory archival data led to the identification of 454 X-ray sources. These sources were then cross-identified with optical photometric and spectroscopic information available from the literature and with newly obtained near-infrared (JHKs) imaging observations. A total of 38 known OB stars are found to be X-ray emitters. All the O stars and early-B stars follow the nominal relation between the X-ray and bolometric luminosities, LX ~ 10-7Lbol. A few mid- to late-B stars are found to be associated with X-ray emission, likely attributable to T Tauri companions. We discovered 16 OB star candidates that suffer a large extinction in the optical wave bands. Some 300 sources have the X-ray and infrared characteristics of late-type pre-main-sequence stars. Our sample represents the most comprehensive census of the young stellar population in the Carina Nebula so far and should be useful for the study of the star formation history of this massive starburst region. We also report the finding of a compact (2' × 4') group of 10 relatively bright X-ray sources, all of which are detected in the near-infrared wavelengths and are highly reddened. The group is spatially coincident with the dark V-shaped dust lane bisecting the Carina Nebula and may be part of an embedded association. The distribution of the young stellar groups surrounding the H II region associated with Trumpler 16 is consistent with the collect-and-collapse scenario of triggered star formation.Item Near-infrared study of the Carina Nebula(IOP, 2007) Vaidya, KausharWe have carried out near-infrared (NIR) imaging observations of the Carina Nebula for an area of ~400 arcmin2 including the clusters Trumpler 14 and Trumpler 16, with 10 σ limits of J ~ 18.5, H ~ 17.5, and Ks ~ 16.5 mag. A total of 544 Class II candidates, 11 Class I candidates, and 40 red (H - Ks > 2) sources have been found. The majority of the Class II candidates are found to be distributed toward the clusters, whereas most of the red NIR sources are concentrated to the southeast of Trumpler 16, along the V-shaped dust lane. We found indications of ongoing star formation near the three MSX sources, G287.51-0.49, G287.47-0.54, and G287.63-0.72, where red NIR sources and X-ray sources are seen. In particular, two hard X-ray sources are identified near G287.47-0.54, one of which does not have an NIR counterpart and may be associated with a Class I/Class 0 object. The color-magnitude diagrams of the clusters suggest very young stellar population (<3 Myr). The Ks-band luminosity function (KLF) of Trumpler 14 shows a sharp peak at the faint end, likely due to the onset of deuterium burning. The KLF of Trumpler 16, in contrast, rises smoothly until it turns over. The slopes of the mass functions derived for the clusters are in agreement with the canonical Salpeter value for the field stars.