Star Forming Regions in Cepheus

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LkHα 234. Ray et al. (1990) identified an optical jet originating from this region.
Mitchell & Matthews (1994) detected a molecular jet associated with LkHα 234, and
Schultz et al. (1995) observed shocked molecular hydrogen in the LkHα 234 region.
VLA observations by Trinidad et al. (2004) of water masers and radio continuum emission
at 1.3 and 3.6 cm show that the LkHα 234 region contains a cluster of YSOs. In
a field of ∼ 5 ′′ they detected five radio continuum sources (VLA 1, VLA 2, VLA 3A,
VLA 3B, and LkHα 234) and 21 water maser spots. These water masers are mainly
distributed in three clusters associated with VLA 1, VLA 2, and VLA 3B. The VLA
observations suggest that there are at least four independent, nearly parallel outflows in
the LkHα 234 region. Probably all sources observed in this region (∼ 5 ′′ in diameter)
form a cluster of YSOs, which were born inside the same core in the NGC 7129 molecular
cloud. This fact could explain that the major axes of the outflows have nearly
the same orientation. Marvel (2005) performed VLBI observations of maser sources
around LkHα 234, and detected maser emission associated with LkHα 234–VLA 2
and LkHα 234–VLA 3b. No maser source associated with LkHα 234 itself has been
detected.
Tommasi et al. (1999) obtained far-infrared spectra of the LkHα 234 region, using
the Long Wavelength Spectrograph of ISO. The observed spectra are consistent with a
photodissociation region, associated with not LkHα 234, but with BD +65 ◦ 1637. Morris
et al. (2004) have obtained mid-IR spectroscopy of regions around LkHα 234, with
the Spitzer Space Telescope Infrared Spectrograph (IRS). They detected warm material
at 16 µm around BD +65 ◦ 1638 which clearly shows that this region is not free of gas
and dust. Wang & Looney (2007) identified a group of low-mass young stars around
LkHα 234 using the Spitzer data base.
Interstellar matter associated with NGC 7129 Molecular line observations of the region
(Bechis et al. 1978; Font, Mitchell & Sandell 2001; Miskolczi et al. 2001; Ridge
et al. 2003) revealed a kidney-shaped molecular cloud of about 11 pc in extent to the
east and south of the cluster. BD +65 ◦ 1637 and most of the fainter cluster members
are found in a cavity of the cloud, bordered by a prominent molecular ridge, while
LkHα 234, located to the east of the main cluster, is associated with a peak of 13 CO
emission. The optical jet detected by Ray et al. (1990) is pointing southwest into the
cavity. Torrelles et al. (1983) and Güsten & Marcaide (1986) presented ammonia observations
of NGC 7129.
Matthews et al. (2003) observed the region in the 21 cm line of H I with an angular
resolution of 1 ′ . The observations revealed a ring of H I emission about 30 ′ in extent.
The H I ring appears to be part of the surface of a molecular cloud and is centered on a
relatively dense concentration of H I with unusually wide line profiles and positionally
coincident with BD +65 ◦ 1638. An infrared point source, IRAS 21418+6552, coincides
within the positional errors with the H I knot.
A continuum source coincident with BD +65 ◦ 1638 has also been detected at 1420
MHz, which shows a significant extension to the northeast overlapping the position
of LkHα 234. Comparing the radio continuum data with other radio observations of
BD +65 ◦ 1638, Matthews et al. (2003) found that BD +65 ◦ 1638 has a flat centimeterwave
spectrum, consistent with an optically thin H II region around the star. The authors
conclude that the physical association of the star with the H I knot indicates that
BD +65 ◦ 1638 belongs to a rare class of “dissociating stars”, having an extremely young
age of not more than a few thousand years. BD +65 ◦ 1638 itself is found to be a 6 M⊙
star that has just emerged from its cocoon and lies on the birthline.