Richard R. Joyce

Tucson Nighttime Scientific Staff


Areas of Interest

Late-type Stars; Mass Loss; Infrared Detector and Instrumentation Development

Recent Research Results

In collaboration with K. Hinkle (NOAO), Joyce has continued monitoring the evolution of Sakurai's Object, a star now recognized as a prototype final helium flash shell object. Since its outburst in 1996, the star had begun to fade visually due to the ejection of a dust shell in 1997, and is now detectable only in the infrared. In June 2000 the infrared spectrum was a featureless continuum (T ~ 600 K), except for a strong HeI 10830 emission line. This line had changed considerably since its previous observation in 1999, suggesting changes in the excitation of the circumstellar material. The star V605 Aql, which underwent a final helium shell flash in 1919 (but was not recognized as such an object until recently), was unambiguously recovered in the infrared using SQIID, and its IR spectrum displays HeI 10830 emission similar to that seen in Sakurai's star.

Joyce and Hinkle sponsored a summer intern student, A. Hedden (Carleton), who was involved in the reduction and publication of the Sakurai and V605 Aql imaging and spectroscopy. In addition, she carried out a project on wavelength calibration of high-resolution PHOENIX spectra. The results of these projects have all been published.

A long-term collaborative program with K. Hinkle (NOAO) and F. Fekel (Tennessee State U.) to determine orbits of symbiotic stars from their infrared spectra (using the Coude Feed telescope) was completed in 2000. Orbital determinations of these systems using optical spectra have been problematic; the infrared spectrum, however, is almost completely that of the cool giant component, and an unambiguous velocity determination of that star is thus possible. The results should not only confirm that symbiotics are mass-transfer binaries, but given the constraints of the white dwarf secondary, could yield accurate stellar masses for cool giants over a range of evolutionary stages. Three publications have appeared in the literature, and at least two more are in work.

Future Research Plans

Joyce, Hinkle, and Fekel are continuing the highly successful symbiotic star radial velocity program from the southern hemisphere, using the same NICMASS IR camera system at the Mt. Stromlo coude spectrograph. Peter Wood (MSSSO) is the local collaborator on this program, which began in March 2001. Almost no information exists for the larger sample of southern symbiotics, and the aperture of the MSO 74-inch telescope has permitted extending the sample to objects 1.5 mag fainter than could be observed at the KPNO coude feed. Joyce and Hinkle plan to continue spectroscopic monitoring of Sakurai's Object and V605 Aql. Both HST and Gemini N (Hokupa'a) time have been awarded to study the spatial extent of the V605 Aql circumstellar shell, which is anticipated to be on the order of 1 arcsec diameter. Comparison of the infrared (dust) and optical (ionized gas) morphology can discriminate between bipolar and lumpy models of the circumstellar shell.

The recent upgrade of PHOENIX to an Aladdin II detector, as part of the plan to deploy this instrument on Gemini South, has resulted in very significant improvements in the sensitivity of this instrument. (The original Aladdin I array had numerous high dark current pixels). This should permit readdressing the project to observe the HeI line at 1.083 microns in metal-poor giant stars. These stars may be considered analogs to the red giants in globular clusters. One such star has been reported in the literature to show a 1.083 micron feature indicative of a high-speed (> 90 km/s) wind. Since this velocity exceeds the escape velocity from globular clusters, the presence of such high-speed winds from metal-poor field stars would suggest a mass loss mechanism for globular cluster giants which could expel matter from the cluster itself and plausibly explain the observed low density of the interstellar medium in globular clusters.

Service

As a Support Scientist, a significant fraction of Joyce's time is spent in providing observing support to visiting observers using the facility instruments CRSP (a low-resolution IR spectrograph), SQIID (IR imager), and PHOENIX (high-resolution IR spectrograph). He will also be involved in visitor support with the new FLAMINGOS (U. Florida multiobject imaging spectrograph) as it comes on-line. This includes direct support such as checking out the instruments after installation, providing instruction to observers, training the Kitt Peak mountain staff in technical issues associated with these instruments, off-line support in providing advice to prospective observers, and assistance with data reduction.

Almost half of his time is devoted to the Gemini Near Infrared Spectrograph (GNIRS) project, on which he is a Project Support Scientist. His extensive involvement in this project has consisted of systems engineering efforts during the concept and design state and the testing of prototypes; he will be heavily involved in the assembly and testing of the instrument prior to its scheduled delivery to Gemini in 2002.

Joyce has also been involved in the concept definition of the next-generation wide-field IR imager for NOAO (NEWFIRM) and is a member of the working team for that instrument. He is also involved in IRMOS project, a collaborative effort of NOAO, StScI, and NASA Goddard to develop an IR multi-object spectrograph utilizing digital multimirror technology. He has committed significant effort in the upgrade of SQIID (now on-line with InSb arrays) and the PHOENIX upgrade for Gemini South.

Other service areas include continuing to assist with the scheduling of Kitt Peak telescopes, serving on the Galactic TAC (2001A semester), the NOAO IPAC, and NOAO Safety Committee.


Recent Publications

  • Pilachowski, C., Sneden, C., Hinkle, K., and Joyce, R.R. 1997, "Carbon Isotope Ratios from the First Overtone CO Bands in Metal-Poor Giants", Astron. J., 114, 819.

  • Joyce, R.R., 1998, "Infrared Spectroscopy of Faint High Galactic Latitude Carbon Stars", Astron. J., 115, 2059.

  • Joyce, R.R., Hinkle, K.H., Meyer, M.R., and Skrutskie, M.F. 1998, "Infrared Astronomical Spectroscopy with a Non-Cryogenic Spectrograph", PROC SPIE, 3354, 741.

  • Joyce, R.R., Hinkle, K. H., Wallace, L., Dulick, M., and Lambert, D.L. 1998, "Spectra of Cool Stars in the J Band (1.0 - 1.3 microns) at Medium Resolution", Astron. J., 116, 2520.

  • Fekel, F.C., Joyce, R.R., Hinkle, K.H., and Skrutskie, M.F. 2000, "Infrared Spectroscopy of Symbiotic Stars. I. Orbits for Well-known S-type Systems", Astron. J., 119, 1375.

  • Fekel, F.C., Hinkle, K.H., Joyce, R.R., and Skrutskie, M.F. 2000, "Infrared Spectroscopy of Symbiotic Stars. II. Orbits for Five S-type Systems with Two Year Periods", Astron. J., 120, 3255.

  • Hinkle, K.H., Joyce, R.R., and Hedden, A. 2001, "Infrared Photometry of the final flash star V605 Aql", Astron. Ap, 367, 250.

  • Fekel, F.C., Hinkle, K.H., Joyce, R.R., and Skrutskie, M.F. 2001, "Infrared Spectroscopy of Symbiotic Stars. III. First Orbits for Three S-type Systems", Astron. J., 121, 2219.

  • Hinkle, K.H., Joyce, R.R., Hedden, A., and Wallace, L. 2001, "Wavelength Calibration of Near-Infrared Spectra", P.A.S.P., 113, 548.



    HeI emission lines in Sakurai's Object (top) and V605 Aql (bottom), obtained with CRSP on the KPNO 2.1-m in 2000.

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    Updated: 13Jun2001