Laser Discovered in BN star

The possibility of laser action in astrophysical sources was considered by Smith (1969), Menzel (1970) and later demonstrated by Varshni (1973, 1979). Smith et al. (1979) discovered that the Becklin-Neugebauer (BN) star in the Orion nebula also emitted laser radiation. Its spectra was observed in the range of 3.3 to 5.5 microns. Atomic hydrogen emission lines of Brackett-alpha and Pfund-beta were seen, as well as molecular CO absorptions. The December 1976 data showed an anomalously high intensity for Pfund-beta line near 4.65 microns. Theoretical considerations suggested that Pfund-beta radiation arises in a small dense region, with the transition possibly lasing. It is not surprising that microwave lasers have also been found in this area (crosses marked on chart below). Smith has observed the Pfund beta intensity anomaly in gamma Cas and zeta Tau, both Be shell stars.

20 micron image of BN area 20 micron infrared image of area near the BN star (in red). This star is a member of the stellar association of young stars in the orion nebula which includes the Trapezium cluster (in blue). The crosses give the positions of OH and H2O masers (hydroxyl and water masers). The image has a resolution of 5 arcseconds. (By permission of Wynn-Williams and Becklin, 1974)
HST Picture of Trapezium cluster
Hubble Space Telescope optical image of Trapezium cluster in the Orion nebula overlayed with infrared contour lines (in yellow) from previous plot. The laser star is prominent in the recent infrared image from the HST
(it is the brightest object in the NICMOS image which covers 0.8 to 2.5 microns of wavelength)

This is an area of active star formation; just below center of the image there is an extended 'comet like' object indicating strong stellar winds. In higher resolution images there are a dozen of these objects oriented radially around Theta1 Orionis (the brightest of the Trapezium stars in this image).

Closeup of BN star at wavelength of 3.8 microns. Field of view is 20 arcseconds across. (Dougados et al., 1993)
Infrared spectrum of BN star taken in December 1976. Covers 4.45 to 4.75 microns. The Pfund beta hydrogen laser emission line is prominent at 4.65 microns. (Smith et al., 1979)

 

REFERENCES

  1. Smith,H.A.: 1969, ApJ., 158, 371. Possibility of laser action in astrophysical sources
  2. Smith,H.A., Larson,H.P., Fink,U.: 1979, ApJ., 233, 132. The spectrum of the Becklin-Neugebauer source in Orion from 3.3 to 5.5 microns
  3. Hall,D.N.B., Ridgway,S.T., Gillett,F.C., Kleinmann,S.G.: 1978, ApJ., 223, 47. High-resolution 1.5-5 micron spectroscopy of the Becklin-Neugebauer source in Orion
  4. Scoville,N.Z., Hall,D.N.B., Ridgway,S.T., Kleinmann,S.G.: 1982, NASA, NSF, New York Academy of Sciences, et al., Symposium on the Orion Nebula to Honor Henry Draper, Annals of the New York Academy of Sciences, 395, p. 125. Gas dynamics in the circumstellar Nebula on the Becklin-Neugebauer source
  5. Scoville,N., Kleinmann,S.G., Hall,D.N.B., Ridgway,S.T.: 1983, ApJ., 275, 201. The circumstellar and nebular environment of the Becklin-Neugebauer object - 2-5 micron wavelength spectroscopy
  6. Dougados,C., Lena,P., Ridgway,S.T., Christou,J.C., Probst,R.G.: 1993, ApJ., 406, 112. (online) Near-infrared imaging of the Becklin-Neugebauer-IRc2 region in Orion with subarcsecond resolution
  7. Scoville,N.Z., Hall,D.N.B., Ridgway,S.T., Kleinmann,S.G.: 1979, ApJ., 232, 121. Detection of CO band emission in the Becklin-Neugebauer object
Laser History

 

Laser Stars