Science - JPL's Science Division: People: Paul Goldsmith

Paul Goldsmith
Chief Technologist, Astronomy and Physics Directorate
NASA Herschel Project Scientist

Dr. Paul Goldsmith's recent work has focused on determining time scales of processes associated with the formation of molecular clouds and young stars. This has included use of atomic hydrogen in molecular clouds as a tracer of their evolution and history. Goldsmith has also worked on determining the conditions for formation of massive stars by using molecular line and dust continuum emission. He has also been using specific tracers of chemistry in the interstellar medium to assess impact of star formation on remaining molecular cloud material via shocks and other processes.

Goldsmith is the NASA Project Scientist for the Herschel Space Observatory, a far-infrared/submillimeter spectroscopic and photometric mission to be launched late in 2008. He is also leading the JPL involvement with the Cornell-Caltech Atacama Telescope (CCAT) project.

A.B. in Physics, University of California, Berkeley (1969)
Ph.D. in Physics, University of California, Berkeley (1975)

Dr. Goldsmith's areas of interest in astronomy include the structure of dense molecular clouds and understanding how star formation occurs within them. This has led to developing techniques for probing the densities, temperatures, and other physical conditions in these regions. In addition to carrying out ground-based and airborne observations, he has also been involved as a co-investigator with the Submillimeter Wave Astronomy Satellite (SWAS), which has been observing the key species ¹³CO, 0₂, H₂0, and atomic carbon from interstellar clouds since its launch in 1998.

Goldsmith has also had an ongoing interest in astronomical instrumentation, especially high-sensitivity systems at centimeter to submillimeter wavelengths. He has also been actively involved in development of focal plane array receivers for radio telescopes at all wavelengths.

Interstellar Medium, Molecular Clouds, Cloud Cores, and Star Formation
Candidates are invited to apply for one or more postdoctoral positions in astrophysics research related to the upcoming Hershel Space Observatory mission. These positions will involve carrying out observations and developing models and software tools for analysis and interpretation of data on interstellar medium, molecular clouds, cloud cores, and star formation. In particular this work will be preparation for data coming from the Herschel Space Observatory, currently scheduled for launch at the end of 2008. Scientists at JPL have a major involvement in this mission and have guaranteed observing time (GT) and include two PIs for Herschel Open Time Key Projects (OTKP). One OTKP, led by Dr. Paul Goldsmith, targets interstellar oxygen chemistry, and the other, led by Dr. William Langer, studies the state of the Galactic diffuse ISM. In preparing for and exploiting data from Herschel, a variety of auxiliary observations will be critical, including submillimeter spectral line and continuum data obtained using facilities including the Caltech Submillimeter Observatory, to which JPL staff have access, the CARMA interferometric array, and other telescopes. The individual(s) in these positions will be expected to carry out his/her program of research and to collaborate with other staff members in observations leading to and complementary to Herschel, as well as participating in activities associated with the Herschel GT and OTKP. Candidates should have experience in some combination of the following, mm/submm observations, data reduction, and modeling of physics, chemistry, excitation, and radiative transfer in the interstellar medium. Experience developing software is highly desirable. Paul Goldsmith, Senior Research Scientist in JPL’s Astrophysics and Space Sciences Directorate, or William Langer, Senior Research Scientist in JPL's Engineering and Science Directorate, will serve as JPL postdoctoral advisor to the selected candidate(s). The appointee will be guided by the JPL postdoctoral advisor to ensure that the research work will result in publications in the open literature.

Studies of Dust and Gas in Star Formation
This research will focus on determining the structure of dense cores in molecular clouds. Young stars form within these condensations, which are characterized by enhanced densities but modest temperatures between 10 K and 20 K. In order to understand the evolution of these cores to stars, we need to unravel their density distribution, which is best traced by thermal dust emission. Determining the column density from the dust continuum, requires good knowledge of the temperature distribution. All of this information resides in far-infrared and submillimeter images of these cores which can be obtained with the CSO and other submm telescopes, as well as the Herschel Space Observatory. To analyze the images, we have available the COREFIT program developed at JPL, which fits a model to a data set, and which allows for super resolution to obtain maximum possible angular resolution. Working with this program applied to existing and forthcoming core images, as well as with maps of various molecular lines serving as tracers of cloud kinematics obtained with the CARMA array, the SMA, and other facility, we can determine the present structure of these cores and their likely future evolution. From accurate measurements of the mass of such cores, we can determine the core mass function and by comparing it to the stellar initial mass function, find out what are the key steps in the transformation of a dense core to a star or stars.

Herschel
The Herschel Space Observatory is a space-based telescope that will study the Universe by the light of the far-infrared and submillimeter portions of the spectrum.

CCAT - Cornell Caltech Atacama Telescope Icon

CCAT - Cornell Caltech Atacama Telescope
The Cornell Caltech Atacama Telescope is a project to build a large submillimeter telescope in the high Andes of northern Chile.

Fellow, Institute of Electrical and Electronics Engineers, 1991
IEEE MTT Distinguished Lecturer, 1992
James Weeks Professor in Physical Sciences, Cornell University, 1999-2005

Recent Publications

"Molecular Depletion and Thermal Balance in Dark Cloud Cores," Goldsmith, P.F., ApJ, 557, 736, 2001.
"Tracing the Infall and the Accretion Shock in the Protostellar Disk L1157," Velusamy, T., Langer, W.D., and Goldsmith, P.F., ApJ, 565, L43, 2002.
"Tentative Detection of Molecular Oxygen in the Rho Ophiuchi Cloud," Goldsmith, P.F., Li, D., Bergin, E.A., Melnick, G.J., Tolls, FV., Howe, J.E., Snell, R.L., and Neufeld, D.A. 2002, ApJ, 576, 814.
"SUBMILLIMETER WAVE ASTRONOMY SATELLITE and Arecibo Observations of H2O and OH in a Diffuse Cloud Along the Line of Sight to W51," Neufeld, D.A., Kaufman, M.J., Goldsmith, P.F., Hollenbach, D.J., and Plume, R. 2002, ApJ, 580, 278.
"Radio Telescopes and Measurements at Radio Wavelengths," Goldsmith, P.F., ASP Conf. Series Vol. 278, Proc. Conf. SingleDish Radio Astronomy Techniques and Applications, S. Stanimirovic, D.R. Altschuler, P.F. Goldsmith, and C.J. Salter eds. San Francisco ASP, 45, 2002.
"HI Narrow Self-Absorption in Dark Clouds," Li, D. and Goldsmith, P.F., 2003, ApJ, 585, 823.
"Massive Quiescent Cores in Orion. I. Temperature Structure," Li, D., Goldsmith, P.F., and Menten, K. 2003, ApJ, 587, 262.
"A 4-6 GHz Spectral Scan and 8-10 GHZ Observations of the Dark Cloud TMC-1," Kalenskii, S.V., Slysh, V.I., Goldsmith, P. F., & Johansson, L.E.B. 2004, ApJ, 610, 329.
"Probing Pre-Protostellar Cores with Formaldehyde," Young, K.E., Lee, J.-E., Evans, N.J. II, Goldsmith, P. F., & Doty, S.D. 2004, ApJ, 614, 252,
"HI Narrow Self-Absorption in Dark Clouds: Correlations with Molecular Gas and Implications for Cloud Evolution and Star Formation," Goldsmith, P. F. & Li, D.2005, ApJ, 622, 938.
"Interstellar Deuterated Ammonia: From NH₃ to ND₃," Roueff, E., Lis, D.C., van der Tak, F.F.S., & Goldsmith, P.F. 2005, A&A, 438, 585.