The Carina star-forming region is one of the largest in the Galaxy, and its massive star population is still being unveiled. The large number of stars combined with high, and highly variable, interstellar extinction makes it inherently difficult to find OB stars in this type of young region. We present the results of a spectroscopic campaign to study the massive star population of the Carina Nebula, with the primary goal to confirm or reject previously identified Carina OB star candidates. A total of 141 known O-and B-type stars and 94 candidates were observed, of which 73 candidates had a high enough signal-to-noise ratio to classify. We find 23 new OB stars within the Carina Nebula, a 32% confirmation rate. One of the new OB stars has blended spectra and is suspected to be a double-lined spectroscopic binary (SB2). We also reclassify the spectral types of the known OB stars and discover nine new SB2s among this population. Finally, we discuss the spatial distribution of these new OB stars relative to known structures in the Carina NSebula. Subject headings: stars -massive -binaries: spectroscopic -open clusters and associations: individual (Carina)
For parents there can be negative aspects of how work 'spills over' to family. This analysis focuses on mothers of young children and considers how aspects of work-to-family strain differ for single and couple mothers. While there has been increased focus on the work-family strains of mothers, less is known about single mothers and their experience of work-family strain. We might expect that single mothers would have more difficulty in combining work and family, given that they do not have the support of a resident partner to assist with childrearing responsibilities. This paper explores the relationships between several demographic, employment and supports factors and work-family strain. It also examines whether these associations are different according to family form; that is, whether certain factors make the work-family balance significantly worse or better for single mothers than for otherwise similar couple-parent mothers. The analysis is based on the 2004 Growing up in Australia: the Longitudinal Study of Australian Children (LSAC). This dataset contains detailed family and child data for around 10,000 families, all with at least one child aged 5 or under. With such a large sample size, the number of single mothers is sufficiently large to enable more analyses than is often possible from survey data.
Massive binary stars may constitute a substantial fraction of progenitors to supernovae and γ-ray bursts, and the distribution of their orbital characteristics holds clues to the formation process of massive stars. As a contribution to securing statistics on OB-type binaries, we report the discovery and orbital parameters for five new systems as part of the Cygnus OB2 Radial Velocity Survey. Four of the new systems (MT070, MT174, MT267, and MT734≡VI Cygni #11) are single-lined spectroscopic binaries while one (MT103) is a double-lined system (B1V+B2V). MT070 is noteworthy as the longest period system yet measured in Cyg OB2, with P =6.2 yr. The other four systems have periods ranging between 4 and 73 days. MT174 is noteworthy for having a probable mass ratio q < 0.1, making it a candidate progenitor to a low-mass X-ray binary. These measurements bring the total number of massive binaries in Cyg OB2 to 25, the most currently known in any single cluster or association.
We report the discovery of a previously unknown massive Galactic star cluster at ℓ = 29.22 • , b = −0.20 • . Identified visually in mid-IR images from the Spitzer GLIMPSE survey, the cluster contains at least 8 late-type supergiants, based on followup near-IR spectroscopy, and an additional 3-6 candidate supergiant members having IR photometry consistent with a similar distance and reddening. The cluster lies at a local minimum in the 13 CO column density and 8 µm emission. We interpret this feature as a hole carved by the energetic winds of the evolving massive stars. The 13 CO hole seen in molecular maps at V LSR ∼ 95 km s −1 corresponds to near/far kinematic distances of 6.1/8.7±1 kpc. We calculate a mean spectrophotometric distance of 7.0 +3.7 −2.4 kpc, broadly consistent with the kinematic distances inferred. This location places it near the northern end of the Galactic bar. For the mean extinction of A V = 12.6 ± 0.5 mag (A K = 1.5 ± 0.1 mag), the color-magnitude diagram of probable cluster members is well fit by isochrones in the age range 18-24 Myr. The estimated cluster mass is ∼ 20, 000 M ⊙ . With the most massive original cluster stars likely deceased, no strong radio emission is detected in this vicinity. As such, this RSG cluster is representative of adolescent massive Galactic clusters that lie hidden behind many magnitudes of dust obscuration. This cluster joins two similar red supergiant clusters as residents of the volatile region where the end of our Galaxy's bar joins the base of the Scutum-Crux spiral arm, suggesting a recent episode of widespread massive star formation there.
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