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 Interstellar and Heliospheric Physics: People
Raghvendra Sahai's Picture
Jet Propulsion Laboratory
M/S 183-900
4800 Oak Grove Drive
Pasadena, CA 91109

Raghvendra Sahai

Dr. Sahai's research has focused on the physics and chemistry of mass-loss in dying stars, using both spectroscopic and continuum techniques, radio and infrared wavelengths. He has over 80 published articles in these areas.

Dr. Sahai's current focus of research is on using NASA's Great Observatories (Hubble Space Telescope, Chandra X-Ray Observatory and Spitzer Space Telescope) to study dying stars with high angular resolution and/or at wavelengths only accesible from space, and modeling of multiwavelength data for detailed object studies.

Dr. Sahai has contributed to the science justification for an infrared high-contrast coronagraphic imaging camera to search for planetary and brown dwarf companions around nearby stars, and circumstellar matter in young, main-sequence and dying stars, as part of the Design Reference Mission for the JWST. He is a member of the Science Team for the ECLIPSE coronagraphic telescope concept for a DISCOVERY-class mission to search for extra-solar giant planets.

He is a full member of the American Astronomical Society and the International Astronomical Union, and a founding member of the European Astronomical Society.

  • Ph.D., California Institute of Technology (1985)
  • MS (Physics, First Class with Distinction), Indian Institute of Technology, Kanpur, India (1978)

Professional Experience
  • Jet Propulsion Laboratory / California Institute of Technology (1992-Present)
    • Principal Research Scientist (2008-Present)
    • Research Scientist, Senior A (2002-2008)
    • Research Scientist (1995-2001)
    • Member, Scientific Organizing Committee, International Conference "Asymmetric Planetary Nebulae IV" (June 2006 - present)
    • Member, Scientific Organizing Committee, International Conference on "Asymmetric Planetary Nebulae III" (July 2002 - Aug 2003)
    • NHST Science Working Group (2002-2003)
    • Member, Science Team, HST's Wide Field and Planetary Camera 2 (1995-1999)
    • National Research Council Senior Resident Research Associate (1992-1995)
  • University of Gothenburg, Sweden (1986-1992)
    • Docent (1990-1992)
    • Post-doctoral Research Associate (1986-1990)
  • University of Texas, Austin, Post-doctoral Research Associate (1985-1986)
  • University of Texas, Austin, Robert A. Welch Foundation Fellow (1984-1985)
Funded Proposals
  • 17 PI, 1 US-PI, and 5 co-I Hubble Telescope GO program awards (1998-2008)
  • 6 PI Chandra X-Ray Observatory GO program awards (2001-2003)
  • 3 PI and 5 co-I Spitzer Space Telescope GO program awards (2004-2006)
  • 2 PI GALEX GO program awards (2004, 2008)
  • 1 US-PI XMM-Newton X-Ray Observatory program award (ESA/NASA) (2007)
  • PI NASA Long Term Space Astrophysics 5-yr award (2005)
  • PI NASA Astrophysics Data Program 3-yr award (2004)
  • PI NASA Long Term Space Astrophysics 5-yr award (1998)
Mentoring and Supervision
  • Gregory Villar (CSU, Pomona), Minority Initiatives Internship Summer Student (2008)
  • Rachael Ainsworth (U. Tennessee, Knoxville), USRP Internship program, (Sep-Dec 2008)
  • Mark Rubin (CSU, Northridge), Academic Part Time, (2007)
  • Dr. M. Stute, Caltech Postdoctoral Scholar at JPL (2005-date)
  • Dr. C-F. Lee, National Research Council Postdoctoral Scholar(2001-2003)
  • Dr. C. Sanchez Contreras, Caltech Postdoctoral Scholar (2000-2002) at JPL
  • D. Ionita-Ariton (Caltech), Caltech Summer Research Undergraduate Fellow at JPL (1999)
  • Dr. A. Dayal, Caltech Postdoctoral Scholar at JPL (1997-1999)
  • B. E. Sugerman (Occidental College), Caltech Summer Research Undergraduate Fellow at JPL (1994)
  • F. Larsson, Senior Undergraduate Research thesis "Time-variability in the rare 29SiO(v=0,J=2-1) maser in NML Tau, other Miras and Orion-KL, University of Gothenburg, Sweden (1992)
  • B. E. Sugerman, Honors Thesis "Models of Kinematic Structure in the Circumstellar Outflows of the AGB Carbon Stars V Hydra Using High-Resolution Spectroscopy of the 4.6μm CO Lines," Occidental College (1992)
  • A. Nummelin, Senior Undergraduate Research thesis "Mass Loss from AGB Stars The Circumstellar Envelope of the Carbon Star V Cygni," Chalmers University of Technology, Sweden (1991-92)
  • JPL Group Supervisor Alternate (2005-present)
  • JPL Section Promotion Advisory Board Reviews (2002-2005)
  • JPL Research and Technology Development Review (2005)
  • Hubble Space Telescope Proposal Review Panel Cycles 10 & 15 (2001 & 2006)
  • Spitzer Space Telescope Proposal Review Panel Cycle 2 (2005)
  • National Optical Astronomy Observatory (NOAO), Proposal Review Panel (2008)
  • JPL Annual Open House Wide Field Planetary Camera 2 Booth (1995-1998)
  • Frequent Referee for papers submitted to Astrophysical Journal, Astronomy and Astrophysics & Monthly Notices of the Royal Astronomical Society (1985-present)
Teaching Experience
  • Advanced Undergraduate Course in "Stars and Stellar Atmospheres," Chalmers University of Technology and University of Gothenburg, Sweden (1988-1992)
  • Advanced Undergraduate Course in "Astronomical Techniques," Chalmers University of Technology and University of Gothenburg, Sweden (1990-1992)

Selected Awards
  • President's Gold Medal, Best Outgoing Undergraduate Student, Indian Institute of Technology, Kanpur, India (1978)

Selected Publications
  • Sahai, R. "Mass-Loss in AGB Stars - Recent Observational Developments," in Sixth Asian-Pacific Regional Meeting on Astronomy of the IAU, held at IUCAA, Pune, India (16-20th Aug 1993), 1995, Journal of Astrophysics & Astronomy, 16, Supplement, p255.
  • Sahai, R. "Hubble Space Telescope Observations of Young Planetary Nebulae," in Asymmetrical Planetary Nebulae II: From Origins to Microstructures, Masachusetts Institute of Technology, Cambridge, MA (3-6 Aug 1999), Eds. J.H. Kastner, N. Soker & S.A. Rappaport, ASP, 199, p209.
  • Sahai, R. "Multi-Polar Structures in Young Planetary and Protoplanetary Nebulae," 2002, IAU Symposium 209, Planetary Nebulae: Their Evolution and Role in the Universe, ASP Conf. Ser., eds. S. Kwok, M. Dopita, & R. Sutherland, p471.
  • Sahai, R. "Sowing the Seeds of Asymmetry: Jet-like Outflows in Pre-Planetary Nebulae and AGB Stars," at Asymmetric Planetary Nebulae III, 2004, ASP Conf. Ser., eds. Meixner, M.; Kastner, J.H.; Balick, B.; Soker, N. 313, 141.
  • Sahai, R. "Polar Outflows & Jets II", at Asymmetric Planetary Nebulae III, 2004, ASP Conf. Ser., eds. Meixner, M.; Kastner, J.H.; Balick, B.; Soker, N. 313, 185.
  • Sahai, R. "From AGB Stars to Planetary Nebulae - How the Journey Begins", at Asymmetric Planetary Nebulae IV, proc. conference held in La Palma, Spain, June 2007, eds. R.L.M. Corradi, A. Manchado & N. Soker (in press)
  • Claussen, M.J., Sahai, R., & Morris, M. "Water Fountains in Pre-Planetary Nebulae", in Asymmetric Planetary Nebulae IV, proc. conference held in La Palma, Spain, June 2007, eds. R.L.M. Corradi, A. Manchado & N. Soker (in press)
  1. "CO 4.6 micron emission lines from the IRC +10216 inner envelope," Sahai, R.; Wannier, P. G. 1985, ApJ, 299, 424.
  2. "The centimeter radio continuum from IRC+10216 and other late-type stars with mass-loss envelopes," Sahai, R.; Claussen, M. J.; Masson, C. R. 1989, A&A, 220, 92.
  3. "A new self-consistent model of circumstellar CO emission for deriving mass-loss rates in red giants. I - The carbon-rich star U Camelopardalis," Sahai, R. 1990, ApJ, 362, 652.
  4. "Discovery of a fast, bipolar mass-outflow from the prototype S-star Pi(1) Gru," Sahai, R. 1992, A&A, 253, L33.
  5. "SEST CO observations of galaxies in the Grus Quartet - NGC 7582 and NGC 7552 Claussen, M. J.; Sahai, R. 1992, AJ, 103, 1134.
  6. "SO and SO2 in mass-loss envelopes of red giants - Probes of nonequilibrium circumstellar chemistry and mass-loss rates," Sahai, R.; Wannier, Peter G. 1992, ApJ, 394, 320.
  7. "Interferometric observations of non-maser SiO emission from circumstellar envelopes of AGB stars - Acceleration regions and SiO depletion," Sahai, R.; Bieging, John H. 1993, AJ, 105, 595.
  8. "Multiple outflows in the bipolar planetary nebula M1-16: A molecular line study," Sahai, R.; Wootten, Alwyn; Schwarz, Hugo E.; Wild, W. 1994, ApJ, 428, 237
  9. "The Boomerang Nebula: The Coldest Region of the Universe?" Sahai, R.; Nyman, Lars-A. 1997, ApJ, 487, L155.
  10. "Imaging of the Egg Nebula (CRL 2688) with WFPC2/HST: A History of AGB/PostAGB Mass Loss," Sahai, R. et al. 1998, ApJ, 493, 301
  11. "The Structure of the Prototype Bipolar Protoplanetary Nebula CRL 2688 (Egg Nebula): Broadband, Polarimetric, and H2Line Imaging with NICMOS on the Hubble Space Telescope," Sahai, R. et al. 1998, ApJ, 492, L163
  12. "Multipolar Bubbles and Jets in Low-Excitation Planetary Nebulae: Toward a New Understanding of the Formation and Shaping of Planetary Nebulae," Sahai, R., Trauger, J. T. 1998, AJ, 116, 1357
  13. "Discovery of a Remarkable Point-Symmetric Proto-Planetary Nebula: Hubble Space Telescope Imaging of IRAS 04296+3429," Sahai, R. 1999, ApJ, 524, L125
  14. "A Highly Collimated Bipolar Outflow in a Proto-planetary Nebula: Hubble Space Telescope Imaging of HEN 401," Sahai, R., Bujarrabal, V., Zijlstra A. 1999, ApJ, 518, L115
  15. "The Water-Fountain Nebula IRAS 16342-3814: Hubble Space Telescope/Very Large Array Study of a Bipolar Protoplanetary Nebula," Sahai, R, Te Lintel Hekkert, P., Morris, M., Zijlstra, A., Likkel, L. 1999, ApJ, 514, L115
  16. "Unraveling the Structure of Aspherical Proto-Planetary Nebulae. I. Hubble Space Telescope Imaging and Hydroxyl Maser Line Observations of Roberts 22," Sahai, R., Zijlstra, A., Bujarrabal, V., Te Lintel Hekkert, P. 1999, AJ, 117, 1408
  17. "The Etched Hourglass Nebula MYCN 18. I. HUBBLE SPACE TELESCOPE Observations," Sahai, R., Dayal, A., Watson, A.M., Trauger, J.T., et al. 1999, AJ, 118, 468
  18. "He2-113: A Multipolar Planetary Nebula with Rings around a Cool Wolf-Rayet Star," Sahai, R., Nyman, L-A., Wootten, A. 2000, ApJ, 543, 880
  19. "The Starfish Twins: Two Young Planetary Nebulae with Extreme Multipolar Morphology," Sahai, R. 2000, ApJ, 537, L43
  20. "Discovery of a Symmetrical Highly-Collimated Bipolar Jet in He2-90," Sahai, R., & Nyman, L-A. 2000, ApJ, 538, L145
  21. "The structure and momentum of multiple collimated outflows in the protoplanetary nebula Frosty Leo," Sahai, R.; Bujarrabal, V.; Castro-Carrizo, A.; Zijlstra, A. 2000, A&A, 360, L9
  22. "A 2000 km/s pristine post-AGB wind in the protoplanetary nebula He3-1475," C. S'anchez Contreras and R. Sahai, 2001, ApJ, 55, L173
  23. "Proper Motions in the Knotty, Bipolar Jet in Henize 2-90," R. Sahai, S. Brillant, M. Livio, E. K. Grebel, W. Brandner, S. Tingay & L-A. Nyman 2002, ApJ, 573, L123
  24. "Shaping Proto-Planetary and Young Planetary Nebulae with Collimated Fast Winds," Lee, C-F. & Sahai, R. 2003, ApJ, 586, 319
  25. "An Icy, Bipolar Pre-Planetary Nebula with Knotty Jets: IRAS22036+5306," Sahai, R., Zijlstra, A., S'anchez Contreras, C., & Morris, M. 2003, ApJ, 586, L81
  26. "High-Resolution Near-Infrared Imaging and Polarimetry of Four Proto-Planetary Nebulae," Su, Kate Y. L.; Hrivnak, B.J.; Kwok, S.; Sahai, R. 2003, AJ, 126, 848
  27. "X-Ray Emission from the Pre-planetary Nebula Henize 3-1475," Sahai, R., Kastner, J.H., Frank, A., Morris, M., Blackman, E.G. 2003, ApJ, 599, L87
  28. "A collimated, high-speed outflow from the dying star V Hydrae," Sahai, R.; Morris, M.; Knapp, G. R.; Young, K.; Barnbaum, C. 2003, Nature, 426, 261
  29. "The kinematics of water masers in the stellar molecular outflow source, IRAS 19134+2131," Imai, H.; Morris, M.; Sahai, R.; Hachisuka, K.; Azzollini F., J. R. 2004, A&A, 420, 265
  30. "Magnetohydrodynamic Models of the Bipolar Knotty Jet in Henize 2-90," Lee, C-F. & Sahai, R. 2004, ApJ, 606, 483
  31. "Physical Structure of the Protoplanetary Nebula CRL 618. II. Interferometric Mapping of Millimeter-Wavelength HCN J = 1-0, HCO+ J = 1-0, and Continuum Emission," Sanchez Contreras, C. and Sahai, R. 2004, ApJ, 602, 960.
  32. "Sculpting a Pre-planetary Nebula with a Precessing Jet: IRAS 16342-3814 Sahai, R.; Le Mignant, D.; Sanchez Contreras, C.; Campbell, R. D.; Chaffee, F. H. 2005, ApJ, 622, L53.
  33. "A Starfish Preplanetary Nebula: IRAS 19024+0044," Sahai, Raghvendra; Sanchez Contreras, Carmen; Morris, Mark 2005, ApJ, 620, 948.
  34. "The disrupted molecular envelope of Frosty Leo," Castro-Carrizo, A.; Bujarrabal, V.; Sanchez Contreras, C.; Sahai, R.; Alcolea, J. 2005, A&A, 431, 979.
  35. "The dark lane of the planetary nebula NGC 6302, Matsuura, M., Zijlstra, A.A., Molster, F.J., Waters, L.B.F.M., Nomura, H., Sahai, R., & Hoare, M.G. 2005, MNRAS, 359, 383
  36. "Radio continuum monitoring of the extreme carbon star IRC+10216" Menten, K.M., Reid, M.~J., Krügel, E., Claussen, M.J., & Sahai, R. 2006, A&A, 453, 301
  37. "The Dust Envelope of the Pre-Planetary Nebula IRAS 19475+3119, Sarkar, G. & Sahai, R. 2006, ApJ, 644, 1171
  38. "First Evidence of a Precessing Jet Excavating a Protostellar Envelope," Ybarra, J. E., Barsony, M., Haisch, K.E., Jr., Jarrett, T.H., Sahai, R., & Weinberger, A.J. 2006, ApJ, 647, L159
  39. "A Study of H2 Emission in the Bipolar Proto-Planetary Nebula IRAS 17150-3224," Hrivnak, B.J., Kelly, D.M., Su, K.Y.L., Kwok, S., Sahai, R. 2006, ApJ, 650, 237
  40. "A Spitzer IRS Spectral Atlas of Luminous 8 micron Sources in the Large Magellanic Cloud," Buchanan, C.L., Kastner, J.H., Forrest, W.J., Hrivnak, B.J., Sahai, R., Egan, M., Frank, A., and Barnbaum, C. 2006, AJ, 132, 1890
  41. "X-Ray Emission from Planetary Nebulae I. Spherically Symmetric Numerical Simulations," Stute, M. and Sahai, R., ApJ, 651, 882
  42. "A Massive Bipolar Outflow and a Dusty Torus with Large Grains in the Pre-Planetary Nebula IRAS 22036+5306, Sahai, R., Young, K., Patel, N.A., Sanchez Contreras, C. and Morris, M. 2006, ApJ, 653 (Dec 20 issue, in press)
  43. "Adaptive Optics Imaging of IRAS 18276-1431: A Bipolar Pre-Planetary Nebula with Circumstellar "Searchlight Beams" and "Arcs", Sanchez Contreras, C., D. Le Mignant, D., Sahai, R., and Morris, M. 2007, ApJ, 656, 1150
  44. "A Quadrupolar Preplanetary Nebula: IRAS19475+3119", Sahai, R., Sanchez Contreras, C., Morris, M., & Claussen, M. 2007, ApJ, 658, 410
  45. "Hydrodynamical Simulations of the Jet in the Symbiotic Star MWC 560. III. Application to X-Ray Jets in Symbiotic Stars", Stute, M., & Sahai, R., 2007, ApJ, 665, 698
  46. "A Spitzer Study of the Mass-Loss Histories of Three Bipolar Preplanetary Nebulae", Do, T., Morris, M., Sahai, R., & Stapelfeldt, K. 2007,ApJ, 134, 1419
  47. "The Spatio-Kinematical Structure and Distance of the Preplanetary Nebula IRAS 19134+2131", Imai, H., Sahai, R., & Morris, M. 2007, ApJ, 669, 424
  48. "Preplanetary Nebulae: An HST Imaging Survey and a New Morphological Classification System", Sahai, R., Morris, M., Sanchez Contreras, C., & Claussen, M. 2007, ApJ, 134, 2200
  49. "High-Velocity Interstellar Bullets in IRAS05506+2414: A Very Young Protostar?", Sahai, R., Claussen, M., Sanchez Contreras, C., Morris, M. & Sarkar, G. 2008, ApJ, 680, 483
  50. "The LMC's Top 250: Classification of the Most Luminous Compact 8 micron Sources in the Large Magellanic Cloud", Kastner, J.H., Thorndike, S.L., Romanczyk, P.A., Buchanan, C., Hrivnak, B.J., Sahai, R., & Egan, M. 2008, ApJ, 136, 1221
  51. "Echelle long-slit optical spectroscopy of evolved stars", Sanchez Contreras, C., Sahai, R., Gil de Paz, A., & Goodrich, R. 2008, ApJ Suppl.Ser.,179, 166
  52. "Binarity in Cool Asymptotic Giant Branch Stars: A Galex Search for Ultraviolet Excesses", Sahai, R., Findeisen, K., Gil de Paz, A., & Sanchez Contreras, C. 2008, ApJ, 689, 1274
  53. "A Study of H2 Emission in Three Bipolar Proto-Planetary Nebulae: IRAS 16594-4656, Hen 3-401, and Rob 22", Hrivnak, B.J., Smith, N., Su, K.Y.L., & Sahai, R., 2008, ApJ, 688, 327
  54. "The Motion of Water Masers in the Pre-Planetary Nebula IRAS 16342-3814", Claussen, M.J., Sahai, R., & Morris, M., 2008, ApJ, in press, (arXiv:0810.1271)
  55. "Detection of X-rays from the jet-driving Symbiotic Star MWC 560", Stute, M. & Sahai, R., A&A (in press)
  56. "Spitzer IRS Spectra of Luminous 8 micron Sources in the Large Magellanic Cloud: testing Color-based Classifications", Buchanan, C., Kastner, J.H., Hrivnak, B.J., Sahai, R., ApJ, (submitted)

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