Open clusters in AurOB2

Abstract

We study the area around the HII region Sh 2-234, including the young open cluster Stock 8, to investigate the extent and definition of the association Aur OB2 and the possible role of triggering in massive cluster formation. We obtained Strömgren and J,H,Ks photometry for Stock 8 and Strömgren photometry for two other cluster candidates in the area, which we confirm as young open clusters and name Alicante 11 and Alicante 12. We took spectroscopy of 33 early-type stars in the area, including the brightest cluster members. We calculate a common distance of $2.80_{-0.24}^{+0.27}$ kpc for the three open clusters and surrounding association. We derive an age 4-6 Ma for Stock 8, and do not find a significantly different age for the other clusters or the association. The star LSV +34 23, with spectral type O8 II(f), is likely the main source of ionization of Sh 2-234. We observe an important population of pre-main sequence stars, some of them with disks, associated with the B-type members lying on the main-sequence. We interpret the region as an area of recent star formation with some residual and very localized ongoing star formation. We do not find evidence for sequential star formation on a large scale. The classical definition of Aur OB2 has to be reconsidered, because its two main open clusters, Stock 8 and NGC 1893, are not at the same distance. Stock 8 is probably located in the Perseus arm, but other nearby HII regions whose distances also place them in this arm show quite different distances and radial velocities and, therefore, are not connected.

29 pages, 17 figures Accepted for publication in MNRAS

References in corpus (15)

• A systematic survey for infrared star clusters with |b|<20deg using 2MASS
• A Classification Scheme for Young Stellar Objects Using the WIDE-FIELD INFRARED SURVEY EXPLORER AllWISE Catalog: Revealing Low-Density Star Formation in the Outer Galaxy
• Trigonometric Parallaxes of Star Forming Regions in the Perseus Spiral Arm
• Spiral structure in the outer Galactic disk. I. The Third Galactic Quadrant
• Star formation in young star cluster NGC 1893
• A new survey of cool supergiants in the Magellanic Clouds
• Stellar contents and star formation in the young open cluster Stock 8
• Different studies of the global pitch angle of the Milky Way's spiral arms
• Sequentially Triggered Star Formation in OB Associations
• Star Formation Across the W3 Complex
• Sejong Open Cluster Survey (SOS). III. The Young Open Cluster NGC 1893 in the H II Region W8
• Massive Stars in the W33 Giant Molecular Complex
• The O- and B-Type Stellar Population in W3: Beyond the High-Density Layer
• Sejong Open Cluster Survey (SOS) - IV. The Young Open Clusters NGC 1624 and NGC 1931
• Insights into the properties of the Local (Orion) spiral arm. NGC 2302: First results and description of the program

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• The star formation environment of the FU Ori type star V582 Aur
• Large scale star formation in Auriga region
• Filamentary Structures and Star Formation Activities in the Sites S234, V582, and IRAS 05231+3512
• The little-studied cluster Berkeley 90. III. Cluster parameters
• NGC 663 as a laboratory for massive star evolution
• Young Stellar Object Candidates in IC 417