High‐Resolution Infrared Observations of GGD 27

Abstract

We present new high spatial resolution data of the GGD 27 complex, obtained both by speckle interferometry and by lunar occultation observations. Additionally, we performed imaging in the wavelength intervals 8-9 μm and 10-13 μm. The combination of these data with earlier VLA radio maps of Marti, Rodriguez, & Reipurth yields new hints on the nature of IRS 7. It also confirms the interpretation by Aspin et al. that their GGD 27 ILL is the illuminator of the reflection nebula north of IRS 2 as well as of IRS 2 itself. By using precise astrometric calibration, we show that IRS 7 is detected at all three wavelengths and presumably is an embedded B2 star. IRS 1 and IRS 17 still appear pointlike in the K band, although the 8.5 μm data indicate some extended emission around IRS 1, which is presumably caused by heated dust. Other objects in the region targeted by lunar occultation observations, such as HL 17, HL 47 (from Hartigan & Lada) and a hitherto anonymous star, hereafter denoted star 11, also appear pointlike in the K' band. These data complete our picture of the formation of massive stars in the region of GGD 27.