School of Physical, Environmental and Mathematical Sciences

Robert Smith

Dr Robert Smith

Visiting Fellow
BSc PhD Melb., FASA, MIAU

 

Telephone: +61 2 6268 8746
Fax: +61 2 6268 8786
Email: r.smith@adfa.edu.au
Location: PEMS Sth, Room 107


My UNSW Research Gateway Profile

Research Interests:
The physics and chemistry of circumstellar and interstellar dust, with particular emphasis on molecular ices found ongrain mantles in dense molecular clouds. Modelling of extinction propertiesof dust grains. Outflows associated with the early and late stages of stellar evolution. Infrared astronomical spectroscopy. Density structure of Bok globules and other dense dust clouds. Infrared astronomical instrumentation development. Laboratory studies of analogues of interstellar dust grains and grain mantles.

Astrophysics - Laboratory astrophysics, Star formation

Biography

Robert took up his appointment at UNSW Canberra in 1990. Prior to that he held positions at the Institute for Astronomy of the University of Hawaii, The Max Planck Institute for Extraterrestrial Physics and The University of California at Irvine. He obtained his PhD, in Infrared Astronomy, from the University of Melbourne in 1983.

Current Research

Dust around evolved stars
Dr Robert Smith with Dr Steve Charnley & Dr Yvonne Pendleton

In the late stages of their evolution, stars go through a phase where they lose substantial amounts of their mass, leading to the formation of a circumstellar dust envelope. This envelope represents a very different environment to the Interstellar Medium and provides a laboratory to study dust and ice formation via condensation from the hot outflowing material from the stellar photosphere. We are studying a number of evolved stars using radiative transfer modeling and
observational infrared spectroscopy, imaging and photometry.

Interstellar medium
Dr Robert Smith, Assoc. Prof. Chris Wright, Dr Garry Robinson with Dr Steve Charnley, Dr Steve Rogers,
Dr Yvonne Pendleton & Dr Harold Butner

We are studying the formation, evolution and composition of the dust component of the interstellar medium, inparticular the molecular ices found in cold, dense molecular clouds. Techniques employed are(i) observational; collecting infrared spectra of astronomical ices at both ground-based and space borne telescopes, (ii) theoretical; modeling the transmission, absorption and scattering properties of dust grains with different ice coatings and modeling different ways of incorporating the ices into the grains, and (iii) laboratory; infrared Fourier transform spectroscopy of analogs of astronomical ices and ice mixtures allows comparison with astronomical spectra.

Star formation
Dr Robert Smith, Prof. Warrick Lawson & Assoc. Prof. Chris Wright

The earliest stages of star formation, young stellar objects (YSO’s) are characterized by a protostellar core, surrounded by an envelope which feeds the core, most likely via an accretion disk. This stage is often accompanied by large scale
energetic outflows of matter from the core/disk. The envelope is normally so dense that only infrared or radio observations are able to penetrate it sufficiently to investigate the core. We are currently studying one such YSO, GGD30, by means of optical spectroscopy and imaging, infrared spectroscopy and imaging and radio interferometric and single dish observations.

Recent Achievements

Dr Robert Smith
The highlight of 2007 was the discovery that the young stellar object (YSO) GGD30 had a Herbig- Haro Object associated with it. Herbig-Haro objects form when the outflows from YSO’s strike the surrounding medium which is subsequently excited by the shock. We are following up this discovery with a study of the disk and outflow associated withGGD30.

Assoc. Prof. Chris Wright in collaboration with Dr Robert Smith
Detection of the 12 micron librational band of water ice toward an embedded young star. This confirms the only published detection of this band 20 years ago from a low signal-to-noise spectrum. Such an observation can only be made from a space telescope. The new data is of a much higher quality, but importantly includes separate spectra of the two components of the binary system. The presence of the band toward this source, but not others, suggests a unique chemistry.

Collaborators

Selected Publications

  1. Smith R.G., 1987. An infrared study of the stellar population in the direction of the Carina Nebula (NGC 3372), MNRAS, 227 :943-965.
  2. Smith R.G., Sellgren K., Tokunaga A.T., 1988. A study of water ice in the 3 micron spectrum of OH231.8+4.2, ApJ, 334 :209-219.
  3. Smith R.G., Sellgren K., Tokunaga A.T., 1989. Absorption Features in the 3 micron Spectra of Protostars, ApJ, 344 :413-426.
  4. Smith R.G., Sellgren K., Brooke T.Y., 1993, Grain Mantles in the Taurus Dark Cloud, MNRAS, 263 :749-766.
  5. Smith R.G., Robinson G., Hyland A.R. Carpenter, G.L., 1994, Molecular ices as temperature indicators for interstellar dust: the 44 m m and 62 m m lattice modes of water ice, MNRAS, 271 :481-489.
  6. Maldoni M.M., Smith R.G., Robinson G.,  Rookyard V.L., 1998, A study of the 2.5-25 micron spectrum of H2O ice, MNRAS, 298 :251-258.
  7. Meyer A.W, Smith R.G., Charnley S.B., Pendleton, Y.J., 1998, H2O ice in the envelopes of OH/IR stars, ApJ, 115 :2509-2514.
  8. Smith R.G., Blum R.D., Quinn D.E., Sellgren K., Whittet D.C.B., 2002, Ice in the Southern Coalsack, MNRAS, 330 : 837-843
  9. Maldoni, M., Egan, M.P., Robinson, G., Smith, R.G., Wright, C., 2004, The phase of H2O ice and the librational band in OH231.8+4.2: new interpretations, MNRAS, 349(2), 665-677.
  10. Maldoni, M., Ireland, T., Smith, R.G., Robinson, G., 2005, Al2O3 dust in OH/IR stars, MNRAS, 362(3) : 872-878.
  11. Rodgers, S.D., Charnley, S.B., Smith, R.G., Butner, H.M., 2007, Chemical chronology of the Southern Coalsack, MNRAS, 379(2) : 807-815.
  12. Smith, R. G., Lawson, W. A., Wright, C. M., 2007, A Herbig-Haro object associated with GGD30 and its exciting
    source
    , MNRAS, 375(1): 257-260.
  13. Smith, R.G. & Wright, C.M., 2010, A silhouette envelope around GGD30IR detected by Spitzer, MNRAS,401(1), 245-251, doi:10.1111/j.1365-2966.2009.15629.x..
  14. Smith, R.G., Charnley, S.B., Pendleton, Y.J., Wright, C.M., Maldoni, M.M. & Robinson, G., 2011, On the formation of interstellar water ice: Constraints from a search for hydrogen peroxide ice in molecular clouds, The Astrophysical Journal, 743(2), 130-1 - 130-13, doi: 10.1088/0004-637X/743/2/131.
  15. Smith, R.G. & Wright, C.M., 2011,The librational band of water ice in AFGL 961: Revisited, MNRAS, 414(4), 3764-3768, 10.1111/j.1365-2966.2011.18721.x.
  16. Cordiner, M.A., Charnley, S.B., Wirstrom, E.S. & Smith, R.G., 2011, Organic chemistry of low-mass star-forming cores. I. 7 mm spectroscopy of Chamaeleon MMS1, The Astrophysical Journal, 744(2), 131-1-131-12, doi: 10.1088/0004-637X/744/2/131.
  17. Robinson, G., Smith, R.G. & Maldoni, M.M., 2012, The waterice librational band: Radiative transfer model for AFGL 961, MNRAS, 424(2), 1530-1542, doi: 10.1111/j.1365-2966.2012.21347.x.