A Survey of Near Infrared Emission in Visual Reflection Nebulae

Abstract

We present a survey for extended 2.2 $\mu$m emission in 20 new visual reflection nebulae, illuminated by stars with temperatures of 3,600 --- 33,000 K. We detect extended 2.2 $\mu$m emission in 13 new nebulae, illuminated by stars with temperatures of 6,800 -- 33,000 K. For most of these 13 nebulae we have measured $J-K$, $H-K$, and $K-L^{\prime }$, as well as obtaining surface brightness measurements at the wavelength of the 3.3 $\mu$m emission feature. All of the reflection nebulae with extended near infrared emission in excess over scattered starlight have very similar near infrared colors and show the 3.3 $\mu$m feature in emission with similar feature-to-continuum ratios. The 3.3 $\mu$m feature-to-continuum ratio ranges from $\sim$3 to $\sim$9, both within individual nebulae and from nebula to nebula, which suggests that the 3.3 $\mu$m feature and its underlying continuum arise from different materials, or from different ranges of sizes within a size distribution of particles. No dependence on the temperature of the illuminating star is seen in the near infrared colors or 3.3 $\mu$m feature-to-continuum ratio, over a factor of two in stellar temperature. This is similar to our previous IRAS results, in which we found no dependence of the ratio of 12 $\mu$m to 100 $\mu$m surface brightnesses in reflection nebulae illuminated by stars with temperatures of 5,000--33,000 K.

38 pages (87 kB), AASTex format. Also 7 Postscript figures (80 kB), tarred, compressed and uuencoded, added with 'figure' command. Postscript file or hardcopy available upon request to [email protected]. ** Sep. 13, 1995: revised Fig. 1. Compressed postscript text+figs now available at ftp://bessel.mps.ohio-state.edu/pub/sellgren/survey.ps.Z ** Accepted, ApJS (Feb. 1996)

Cited by in corpus (16)

• Infrared Emission from Interstellar Dust. II. The Diffuse Interstellar Medium
• Do the Infrared Emission Features Need Ultraviolet Excitation
• The 15-20 um emission in the reflection nebula NGC2023
• Discovery of Reflection Nebulosity Around Five Vega-like Stars
• Near-Infrared Spectroscopy of Molecular Hydrogen Emission in Four Reflection Nebulae: NGC 1333, NGC 2023, NGC 2068, and NGC 7023
• A near-infrared excess in the continuum of high-redshift galaxies: a tracer of star formation and circumstellar disks?
• High-resolution mapping of interstellar clouds with near-infrared scattered light
• Investigating the Nature of Variable Class I and Flat Spectrum Protostars Using 2-4$\mu$m Spectroscopy
• Dust Emission Features in NGC 7023 between 0.35 and 2.5 micron: Extended Red Emission (0.7 micron) and Two New Emission Features (1.15 and 1.5 micron)
• A Corona Australis cloud filament seen in NIR scattered light I. Comparison with extinction of background stars
• Spatial Separation of the 3.29 micron Emission Feature and Associated 2 micron Continuum in NGC 7023
• A simple connection between the near- and mid-infrared emission of galaxies and their star-formation rates
• Galactic Latitude Dependence of Near-Infrared Diffuse Galactic Light : Thermal Emission or Scattered Light?
• Mapping of interstellar clouds with infrared light scattered from dust: TMC-1N
• Dust emission, extinction, and scattering in LDN 1642
• Tracing PAH Size in Prominent Nearby Mid-Infrared Environments