Compact radio sources in the vicinity of the ultracompact HII region G78.4+2.6

Citlali Neria, Yolanda Gómez, Luis F. Rodríguez


Using the Very Large Array (VLA) at 3.6 cm we identify four new compact radio sources in the vicinity of the cometary HII region G78.4+2.6 (VLA 1). The four compact radio sources (named VLA 2 to VLA 5), have near-infrared counter-parts, as seen in the 3.6 μm Spitzer image. One of them (VLA 5) clearly shows evidence of radio variability in a timescale of hours. We explore the possibility that these radio sources are associated with pre-main sequence (PMS) stars in the vicinity of the UC HII region G78.4+2.6. Our results favor the smaller distance value of 1.7 kpc for G78.4+2.6. In addition to the detection of the radio sources in the vicinity of G78.4+2.6, we detected another group of five sources which appear located about 3′ to the northwest of the HII region. Some of them exhibit extended emission.


HII regions; ISM: individual (G78.4+2.6, IRAS 20178+4046); radio continuum: stars

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