Hubble Space Telescope Imaging of the WR 38/WR38a Cluster

Abstract

We are conducting a high angular resolution imaging survey of Galactic Wolf-Rayet stars using the Wide Field and Planetary Camera 2 aboard the Hubble Space Telescope. We have found a small stellar cluster associated with the faint, close pair WR 38 and WR 38a. We present astrometric measurements and photometry in the wide-band F336W (U), F439W (B), and F555W (V) filter system for these cluster and nearby stars. We compare their colors and magnitudes with calibrated model results for reddened stars to identify seven probable main sequence members of the cluster. A least-squares fit of the colors and magnitudes of this set yields a cluster reddening of E(B-V) = 1.45 +/- 0.14 mag and a distance of 3.7^{+3.8}_{-1.2} kpc. We discuss the relationship of this cluster to other objects along the line of sight, and we argue that the distance probably lies in the range 5 - 8 kpc (but is not as great as 14.5 kpc distance recently advocated by Shorlin, Turner, & Pedreros). At a distance of 8 kpc, the cluster would reside in a dense region of the Carina spiral arm, close to a giant molecular cloud and the starburst cluster NGC 3603.

arXiv commentSubmitted to AJ, 24 pages, 3 figures Content is significantly changed

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Cited by in corpus (5)

• The Galactic WC stars: Stellar parameters from spectral analyses indicate a new evolutionary sequence
• Unlocking Galactic Wolf-Rayet stars with $\text{Gaia}$ DR2 II: Cluster and Association membership
• Searching for spiral features in the outer Galactic disk. The field towards WR38 and WR38a
• The variability of the BRITE-est Wolf-Rayet binary, ${\gamma }^2$ Velorum I. Photometric and spectroscopic evidence for colliding winds
• WR 38/38a and the ratio of total-to-selective extinction in Carina