We 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 nearinfrared (JHK s) 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, L X ∼ 10 −7 L bol. A few mid-to late-type 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 wavebands. Some 300 sources have the Xray 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 This is an unedited preprint of an article accepted for publication in The Astrophysical Journal. The final published article may differ from this preprint.

We have carried out near-infrared (NIR) imaging observations of the Carina Nebula for an area of~400 arcmin 2 including the clusters Trumpler 14 and Trumpler 16, with 10 limits of J $ 18:5, H $ 17:5, and K s $ 16:5 mag. A total of 544 Class II candidates, 11 Class I candidates, and 40 red (H À K s > 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, G287.51À0.49, G287.47À0.54, and G287.63À0.72, where red NIR sources and X-ray sources are seen. In particular, two hard X-ray sources are identified near G287.47À0.54, 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 K s -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.

We present cross-identification of archived ROSAT X-ray point sources with W UMa variable stars found in the All-Sky Automated Survey. A total of 34 W UMa stars have been found associated with X-ray emission. We compute the distances of these W UMa systems and hence their X-ray luminosities. Our data support the ''supersaturation'' phenomenon seen in these fast rotators, namely that the faster a W UMa star rotates, the weaker its X-ray luminosity.

The pulsating DA white dwarfs are the coolest degenerate stars that undergo self‐driven oscillations. Understanding their interior structure will help us to understand the previous evolution of the star. To this end, we report the analysis of more than 200 h of time‐resolved CCD photometry of the pulsating DA white dwarf star EC 14012−1446 acquired during four observing epochs in three different years, including a coordinated three‐site campaign. A total of 19 independent frequencies in the star's light variations together with 148 combination signals up to fifth order could be detected. We are unable to obtain the period spacing of the normal modes and therefore a mass estimate of the star, but we infer a fairly short rotation period of 0.61 ±0.03 d, assuming the rotationally split modes are ℓ= 1. The pulsation modes of the star undergo amplitude and frequency variations, in the sense that modes with higher radial overtone show more pronounced variability and that amplitude changes are always accompanied by frequency variations. Most of the second‐order combination frequencies detected have amplitudes that are a function of their parent mode amplitudes, but we found a few cases of possible resonantly excited modes. We point out the complications in the analysis and interpretation of data sets of pulsating white dwarfs that are affected by combination frequencies of the form fA+fB−fC intruding into the frequency range of the independent modes.