Optical, radio, and infrared observations of compact H II regions. V. The hourglass in M8

Journal Article · Tue Apr 01 04:00:00 EST 1986 · Astron. J.; (United States)

DOI:https://doi.org/10.1086/114065· OSTI ID:6060902

Woodward, C E; Pipher, J L; Helfer, H L; Sharpless, S; Moneti, A; Kozikowski, D; Oliveri, M; Willner, S P; Lacasse, M G; Herter, T

Multiwavelength observations of the inner core of the M8 Hourglass region are presented, including VLA interferometric maps, 2--4 ..mu..m and 8--13 ..mu..m spectroscopy, photometric mapping in the K (2.2 ..mu..m) and L (3.45 ..mu..m) bands and in the 3.28 ..mu..m dust-emission feature, optical CCD imaging, and optical and infrared polarimetry. The compact H II region is excited by the O7 V star Herschel 36, and its apparent bipolar structure at optical wavelengths may be due to variable line-of-sight extinction and scattered light. Standard reddening laws are not applicable in the Hourglass region. A power law extinction lambda/sup -0.78/ yields consistent agreement between ultraviolet, optical, and infrared extinction estimates and suggests that one component of the total grain distribution is on the average larger than that found in the interstellar medium. The spatial distribution of the 3.28 ..mu..m dust-emission feature shows that the feature emission is associated with the boundary layer in the H II region/molecular cloud interface. The observations favor models in which feature emission comes from small refractory grains rather than from fluorescence or thermal emission from volatile mantles.

• Research Organization: The C. E. K. Mees Observatory, University of Rochester, Rochester, New York 14627
• OSTI ID: 6060902
• Journal Information: Astron. J.; (United States), Journal Name: Astron. J.; (United States) Vol. 91:4; ISSN ANJOA
• Country of Publication: United States
• Language: English

Related Subjects

640103* -- Astrophysics & Cosmology-- Quasi-Stellar
Radio
& X-Ray Sources-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMIC DUST
COSMIC GASES
COSMIC RADIO SOURCES
DUSTS
FLUIDS
GASES
H2 REGIONS
MORPHOLOGY
NEBULAE