Gas (and Ice) in Disks Around Young Stars
My current research concentrates on searching for and characterizing volatiles in disks and envelopes around young stars. We primarily use the high dispersion echelle spectrograph NIRSPEC on Keck II located on Mauna Kea, HI for gas phase work. Ice studies are performed using the SpeX spectrometer on the Infrared Telescope Facility (also on Mauna Kea) and archival Spitzer Space Telescope data. I am looking for (among other things) CH4 gas in disks surrounding low mass young stars. Why? Well, we know CH4 gas is on interstellar ices towards massive young stellar objects like NGC7538 IRS9 where it is about 2% or so as abundant as water. Warm CH4 gas is also seen in these regions. It is also one of the principle parent volatiles in comets, usually found to be about 1% as abundant as water. And, afterall, comets formed under what should be similar to conditions in disks around low mass young stars.
It is thought that methane forms primarily by addition of H atoms one by one onto a C atom that is sticking to a cold dust grain in a dark cloud. This is the same way water forms (adding 2 H to an O atom). CH4 should be part of the initial ice/gas composition around lower mass stars too and as the ices are heated (close to the young star) the CH4 should be in the gas phase.
We are also looking for other common volatiles, including HCN, acetylene (C2H2), ethane (C2H6), that are found in comets and ices and should be detectable in disks around young stars.
Below is a list of my Interstellar Ice and Gas Publications:
(Publications can be viewed at the NASA Astrophysics Data System)
Brown, L. R., Troutman, M. R., Gibb, E. L., 2013, ApJ, 770, L14. “A Spectro-Astrometric Study of Water in DR Tauri”
Horne, D., Gibb, E. L., Brittain, S. D., Rettig, T., Tilley, D., 2012, ApJ, 754, 64-73. “The gas/dust ratio of circumstellar disks: Testing models of planetesimal formation”
Wilking, B. A., Marvel, K. B., Claussen, M. J., Gerling, B. M., Wootten, A., Gibb, E. L. 2012, ApJ, 753, 143. “A Proper Motion Study of the Haro 6-10 Outflow”
Gibb, E. L., Brittain, S. D., Rettig, T. W., Troutman, M., Simon, T., Kulesa, C. 2010, ApJ, 715, 757. “CO and H3+ Toward MWC 1080, MWC 349, and LkHa 101”. Gibb2010_MWC.pdf
Brittain, S. D., Rettig, T. W., Simon, Theodore, Gibb, E. L., Liskowsky, J. 2010, ApJ, 708, 109. “Near Infrared Spectroscopic Study of V1647 Ori”
Gibb, E. L., Van Brunt, K. A., Brittain, S. D., Rettig, T. 2008, ApJ, 660, 1572. Erratum: “Warm HCN, C2H2, and CO in the Disk of GV Tau” Gibb2007_GVTau.pdf
Note: See Erratum: Gibb, E. L., Van Brunt, K. A., Brittain, S. D., Rettig, T. 2008, ApJ, 686, 748. Erratum: “Warm HCN, C2H2, and CO in the Disk of GV Tau”
Brittain, S. D., Rettig, T. W., Simon, T., Balsara, D. S., Tilley, D., Gibb, E. L., Hinkle, K. H. 2007, ApJL, 670, L29-32. “Post-Outburst Observations of V1647 Ori: Detection of a Brief, Warm Molecular Outflow” Brittain2007_MNO.pdf
Whittet, D. C. B., Shenoy, S. S., Bergin, E. A., Chiar, J. E., Gerakines, P. A., Gibb, E. L., Melnick, G. J., Neufeld, D. A. 2007, ApJ, 655, 332. “The Abundance of Carbon Dioxide Ice in the Quiescent Intracloud Medium” Whittet2007_CO2.pdf
Rettig, T., Brittain, S.D., Gibb, E.L., Simon, T., Balsara, D.S., Tilley, D.A., Kulesa, C. 2006, ApJ, 646, 342, “Gas and Dust Stratification in Young Disks”
Gibb, E.L., Rettig, T., Brittain, S.D., Simon, T., Vacca, W.D., Cushing, M.C., & Kulesa, C. 2006, ApJ, 641, 383, “Post-Outburst Infrared Spectra of V1647 Ori, the Illuminating Source of McNeil’s Nebula” Gibb2006_MNO.pdf
Rettig, T., Brittain, S.D., Gibb, E.L., Simon, T., & Kulesa, C. 2005, ApJ, 626, 245. “CO Emission and Absorption toward v1647 Ori (McNeil’s Nebula)”
Rettig, T., Haywood, J., Simon, T., Brittain, S.D., & Gibb, E.L. 2004, ApJL, 616, 163. "Discovery of CO gas in the inner disk of TW Hydrae” Rettig2004_TWHya.pdf
Gibb, E.L., Brittain, S.D., Rettig, T., Haywood, R., Simon, T., Kulesa, C., 2004, ApJ, 610, L113. “Upper Limit for CH4 in the Protostellar Disk towards HL Tau" Gibb2004_HLTau.pdf
Gibb, E.L., Whittet, D.C.B., Boogert, A.C.A., Tielens, A.G.G.M. 2004, ApJS, 151, 35. “Interstellar ice: The ISO legacy” Gibb2004_ISO.pdf
Gibb, E.L. & Whittet, D.C.B., 2002, ApJL, 556, 113. “The 6 μm Feature in Protostars: Evidence for Organic Refractory Material.” Gibb2002_Org.pdf
Chiar, J.E., Adamson, A.J., Pendleton, Y.J., Whittet, D.C.B., Caldwell, D. A., & Gibb, E.L. 2002, ApJ, 570, 198. “Hydrocarbons, Ices, and “XCN” in the Line of Sight Toward the Galactic Center” Chiar2002_GC.pdf
Gibb, E.L., Whittet, D.C.B. & Chiar, J.E. 2001, ApJ, 558, 702. “Searching for Ammonia in Grain Mantles Toward Massive YSOs.” Gibb2001_NH3.pdf
Nummelin, A., Whittet, D.C.B., Gibb, E.L., Gerakines, P.A. & Chiar, J.E. 2001, ApJ, 558, 185. “Solid Carbon Dioxide in Regions of Low-Mass Star Formation” Nummelin2001_CO2.pdf
Whittet, D.C.B., Pendleton, Y.J., Gibb, E.L., Boogert, A.C.A., Chiar, J.E. & Nummelin, A. 2001, ApJ, 550, 793. “Observational Constraints on the Abundance of ‘XCN’ in Interstellar Grain Mantles” Whittet2001_XCN.pdf
Whittet, D.C.B., Gibb, E.L., & Nummelin, A. 2001, Origins of Life Evol. Biosphere, 21, 157. “Interstellar Ices as a Source of CN-Bearing Molecules in Protoplanetary Disks” Whittet2001_OLEB.pdf
Gibb, E.L., Nummelin, A., Bergman, P., Irvine, W. & Whittet, D.C.B. 2000, ApJ, 545, 309. “Chemistry of the Organic-Rich Hot Core G327.3-0.6” Gibb2000_G327.pdf
Gibb, E.L., Whittet, D.C.B., Schutte, W.A., Boogert, A.C.A., Chiar, J.E., Ehrenfreund, P., Gerakines, P.A., Keane, J.V., Tielens, A.G.G.M., van Dishoeck, E.F. & Kerkhof, O. 2000, ApJ, 536, 347. “An Inventory of Interstellar Ices Toward the Embedded Protostar W33A” Gibb2000_W33a.pdf
