X-Ray Emission from the Pre-planetary Nebula Henize 3-1475

Raghvendra Sahai, California Institute of Technology
Joel H. Kastner, Rochester Institute of Technology
Adam Frank, University of Rochester
Mark Morris, University of California
Eric G. Blackman, University of Rochester

© 2003 The American Astronomical Society

We are thankful for partial financial support for this work provided by NASA through its Long Term Space Astrophysics program (grant no. 399-30-61-00-00) for R.S. and M.M., as well as through Chandra Awards GO2-3029X (for R.S.) and GO2-3009X (for J.H.K./RIT) issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory on behalf of NASA under contract NAS8-39073.

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We report the first detection of X-ray emission in a pre-planetary nebula, Hen 3-1475. Pre-planetary nebulae are rare objects in the short transition stage between the Asymptotic Giant Branch and planetary nebula evolutionary phases, and Hen 3-1475, characterized by a remarkable S-shaped chain of optical knots, is one of the most noteworthy members of this class. Observations with the Advanced CCD Imaging Spectrometer (ACIS) onboard the Chandra X-Ray observatory show the presence of compact emission coincident with the brightest optical knot in this bipolar object, which is displaced from the central star by 2.7" along the polar axis. Model fits to the X-ray spectrum indicate an X-ray temperature and luminosity, respectively, of (4.3 − 5.7)×10^6 K and (4 ± 1.4) × 10^31 (D/5 kpc)^2 erg s^−1, respectively. Our 3-sigma upper limit on the luminosity of compact X-ray emission from the central star in Hen 3-1475 is ~5 × 10^31 (D/5 kpc)^2 erg s^−1. The detection of X-rays in Hen 3-1475 is consistent with models in which fast collimated post-AGB outflows are crucial to the shaping of planetary nebulae; we discuss such models in the context of our observations (Refer to PDF file for exact formulas).