An Optical Survey of the Partially Embedded Young Cluster in NGC 7129

Creators: Dahm, S. E.; Hillenbrand, L. A.

Abstract

NGC 7129 is a bright reflection nebula located in the molecular cloud complex near l = 105◦.4, b = +9◦. 9,, about 1.15 kpc distant. Embedded within the reflection nebula is a young cluster dominated by a compact grouping of four early-type stars: BD+65°1638 (B3V), BD+65°1637 (B3e), SVS 13 (B5e), and LkHα 234 (B8e). About 80 Hα emission sources brighter than V ~ 23 are identified in the region, many of which are presumably T Tauri star members of the cluster. We also present deep (V ~ 23), optical VR_(C)I_C photometry of a field centered on the reflection nebula and spectral types for more than 130 sources determined from low dispersion, optical spectroscopy. The narrow pre-main sequence evident in the color–magnitude diagram suggests that star formation was rapid and coeval. A median age of about 1.8 Myr is inferred for the Hα and literature-identified X-ray emission sources having established spectral types, using pre-main sequence evolutionary models. Our interpretation of the structure of the molecular cloud and the distribution of young stellar objects is that BD+65°1638 is primarily responsible for evacuating the blister-like cavity within the molecular cloud. LkHα 234 and several embedded sources evident in near-infrared adaptive optics imaging have formed recently within the ridge of compressed molecular gas. The compact cluster of low-mass stars formed concurrently with the early-type members, concentrated within a central radius of ~0.7 pc. Star formation is simultaneously occurring in a semi-circular arc some ~3 pc in radius that outlines remaining dense regions of molecular gas. High dispersion, optical spectra are presented for BD+65°1638, BD+65°1637, SVS 13, LkHα 234, and V350 Cep. These spectra are discussed in the context of the circumstellar environments inferred for these stars.

Additional Information

© 2015 The American Astronomical Society. Received 12 February 2015, accepted for publication 19 March 2015; published 27 May 2015. This paper is dedicated to the memory of George H. Herbig who passed away on 2013 October 12 at the age of 93 after a career spanning more than 70 years. He is considered by many to be the father of observational star formation, and as a testament to the impact of his contributions upon the field, classes of pre-main sequence objects now bear his name. An intellectual giant, his extraordinary physical insight, natural curiosity, and uncanny ability to ask the right questions led to tremendous advances in our understanding of the star formation process. There are few papers today on the subject of star formation that cannot trace their origins back to work initiated by George during his time at Lick Observatory, the University of California at Santa Cruz, and at the Institute for Astronomy, University of Hawaii. We have made use of the Digitized Sky Surveys, which were produced at the Space Telescope Science Institute under U.S. Government grant NAG W-2166, the SIMBAD database operated at CDS, Strasbourg, France, and the 2MASS, a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center (IPAC)/California Institute of Technology, funded by NASA and the National Science Foundation. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/ California Institute of Technology, funded by the National Aeronautics and Space Administration. This research has made use of the Keck Observatory Archive, which is operated by the W. M. Keck Observatory and the NASA Exoplanet Science Institute (NExScI), under contract with the National Aeronautics and Space Administration. We thank Sirin Caliskan for early work on the LRIS data, performed as an undergraduate at Caltech and the referee whose suggestions improved the quality of the manuscript. Facilities: Keck:I - , Keck:II - , Spitzer - Spitzer Space Telescope satellite, Chandra - , FCRAO - Five College Radio Astronomy Observatory's Telescope, UH:2.2 m - , WIYN - Wisconsin-Indiana-Yale-NOAO Telescope, Mayall - Kitt Peak National Observatory's 4 meter Mayall Telescope

Attached Files

Published - 1538-3881_149_6_200.pdf

Submitted - 1503.06230v1.pdf

Files

1538-3881_149_6_200.pdf

Files (5.0 MB)

Name	Size	Download all
1538-3881_149_6_200.pdf md5:588fa0771545200fa3ddf2b3a873afdc	2.6 MB	Preview Download
1503.06230v1.pdf md5:3e836d94730536277fc757aa29a5cb15	2.5 MB	Preview Download

Additional details

	All versions	This version
Views	0	0
Downloads	0	0
Data volume	0 Bytes	0 Bytes