Discovery of two embedded clusters with WISE in the high Galactic latitude cloud HRK 81.4-77.8

Abstract

Molecular clouds at very high latitude ($b>60^{\circ }$) away from the Galactic plane are rare and in general are expected to be non-star-forming. However, we report the discovery of two embedded clusters (Camargo 438 and Camargo 439) within the high-latitude molecular cloud HRK 81.4-77.8 using WISE. Camargo 439 with Galactic coordinates $\ell =81.11^{\circ }$ and $b=-77.84^{\circ }$ is an $\sim 2$ Myr embedded cluster (EC) located at a distance from the Sun of $d_{\odot }=5.09\pm 0.47$ kpc. Adopting the distance of the Sun to the Galactic centre $R_{\odot }=7.2$ kpc we derive for Camargo 439 a Galactocentric distance of $R_{GC}=8.70\pm 0.26$ kpc and a vertical distance from the plane of $-4.97\pm 0.46$ kpc. Camargo 438 at $\ell =79.66^{\circ }$ and $b=-78.86^{\circ }$ presents similar values. The derived parameters for these two ECs put HRK 81.4-77.8 in the halo at a distance from the Galactic centre of $\sim 8.7$ kpc and $\sim 5.0$ kpc from the disc. Star clusters provide the only direct means to determine the high latitude molecular cloud distances. The present study shows that the molecular cloud HRK 81.4-77.8 is currently forming stars, apparently an unprecedented event detected so far among high latitude clouds. We carried out a preliminary orbit analysis. It shows that this ECs are the most distant known embedded clusters from the plane and both cloud and clusters are probably falling ballistically from the halo onto the Galactic disc, or performing a flyby.

7 pages, 7 figures, and 2 tables in MNRAS, 2015

References in corpus (11)

• Gas expulsion and the destruction of massive young clusters
• A Large Catalog of Accurate Distances to Molecular Clouds from PS1 Photometry
• Dark matter in the Milky Way, II. the HI gas distribution as a tracer of the gravitational potential
• Open clusters in dense fields: the importance of field-star decontamination for NGC5715, Lynga4, Lynga9, Trumpler23, Trumpler26 and Czernik37
• Smith's Cloud: A High-velocity Cloud Colliding with the Milky Way
• Hydrodynamical simulations of Galactic fountains I: evolution of single fountains
• The Ophiuchus Superbubble: A Gigantic Eruption from the Inner Disk of the Milky Way
• The Smith Cloud and its dark matter halo: Survival of a Galactic disc passage
• New Galactic embedded clusters and candidates from a WISE Survey
• Exploring FSR open cluster candidates within $|\Delta \ell |=20^{\circ }$ of the Galactic anticentre
• Towards a census of the Galactic anticentre star clusters II: exploring lower overdensities

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• On the existence of young embedded clusters at high Galactic latitude