Astronomical Research Activities
Robert M. Hjellming
Between 1963 and 1970 my principal research involved theoretical work on the interstellar medium in general, and HII regions and radio recombination lines in particular.
From 1970 to the present my main research area has been the study of stellar systems that produce radio emission. In recent years this has mainly involved observations and interpretation of classical novae, X-ray binaries, and X-ray transients. Most of the radio-emitting X-ray transients that I have worked on are black hole binaries (GS2000+35, V404 Cyg, Nova Muscae 1991, GRO J0422+32, GRO J1655-40, XTE J1748-248). GRO J1655-40 has been proven to be an eclipsing and spectroscopic binary with a FIV star orbiting around a 7.0 solar mass black hole with a 2.92 day period. Recently VLBA imaging of relativistic jets in the X-ray binaries Cyg X-3 and SS433 has been part of this program.
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The Radio Counterpart of XTE J1859+226 |
VLA Detection Image and Initial Radio Light Curve for XTE J1859+226 |
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The Detection, Monitoring, and Imaging of the Radio Counterpart of XTE J11819-254 (=SAX J1819.3-2525=V4641 Sgr) |
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The Radio Counterpart of XTE J1748-288 with multiple relativistic jet ejection events. |
The radio jet images from Aug. 9 and 14, 1998, and radio and X-ray light curves |
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The Radio Counterpart of XTE J2012+38. |
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Discovery of the Radio Counterpart of the |
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Discovery of the Radio Counterpart of the |
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Discovery of the Radio Counterpart of the |
Image of Counterpart on Feb. 21, 1998 |
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Radio Search for the X-ray Transient |
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Radio Search for the X-ray "Nova" GRS 1737-31 |
Preliminary results of VLA observations of the field of GRS 1737-31. |
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Radio Counterpart of the X-ray "Nova" |
To see VLA radio images showing the evidence for the detection of the radio counterpart of GRS1739-278, click on Changing Radio Counterpart. Comparison of X-ray and Radio light curves during the 1996 event. Optically thin radio spectrum evolution before, after, and during the rise of the initial radio event. |
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Return of the Radio Counterpart of the Superluminal Jet Source GRO J1655-40 |
If you want to see VLA 4.8 GHz radio images showing GRO J1655-40 on May 20, 1996, before its return, and when it was seen (for the first time since December 1994) with the VLA on May 29, click on Radio Images , or look at the RXTE ASM and VLA Light Curve. |
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Radio and X-ray Observations of the 1998 Outburst of the Recurrent X-ray Transient 4U 1630-47 |
R.M. Hjellming, M.P. Rupen, A.J. Mioduszewski, E. Kuulkers, M.McCollough, B.A. Harmon, M. Buxton, R. Sood, A. Tzioumis, D. Rayner, S. Dieters, and P. Durouchoux, 1999, Ap.J., 514, 383-387 |
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The Shell of QU Vulpeculae at 2.2 microns, Halpha, and 3.6cm |
Shin, J.-Y., Gehrz, R.D., Jones, T.J., Krautter, J., Heidt, J., and Hjellming, R.M., 1999, A.J., 116, 1966-1970 |
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Aql X-1: Some Unexpected Results |
Garcia, M.R., Callanan, P.J., McCarthy, J, Eriksen, K, and Hjellming, R.M., 1999, Ap. J. (Letters), 518,422-427 |
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Discovery of Correlated Behavior Between the Hard X-ray Bands in Cygnus X-3 |
McCullough, M.L., Robinson, C.R., Zhang, S.N., Harmon, B.A., Hjellming, R.M., Waltman, E.B., Foster, R.S., Ghigo, F.D., and Johnston, K.J., 1999, Ap. J. , 517, 951-955 |
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An Image of a Highly Relativistic Jet from a Large Flare in the X-Ray Binary Cyg X-3 |
Mioduszewski, A.J., Hjellming, R.M., Rupen, M.P., Waltman, E.B., Pooley, G.G., Ghigo, F.D., and Fender, R.P., 1998, In IAU Colloquium 164, High Resolution Imaging in Radio Astronomy, A.S.P. Conf. Series, 144, 351-352, Ed. J.A. Zensus, G.B. Taylor, & J.M. Wrobel |
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High Resolution Imaging of Compact Radio Sources by Gridding with Regularization |
S.F. Likachev and R.M. Hjellming, 1998, In IAU Colloquium 164, High Resolution Imaging in Radio Astronomy, A.S.P. Conf. Series, 144, 411-412, Ed. J.A. Zensus, G.B. Taylor, & J.M. Wrobel |
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RXTE Observations of Cygnus X-3 |
M.L. McCullough, C.R. Robinson, S.N. Zhang, B.A. Harmon, W.S., Paciesas, S.W. Dieters, R.M. Hjelling, M. Rupen, A.J. Mioduszewski, E.B. Waltman, F.D. Ghigo, G.G. Pooley, R.P. Fender, W. Cui, and S. Trushkin. 1998, New Astronomy Reviews, 42, 629-632 |
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Imaging Relativistic Radio Jets and the X-ray--Radio Connection in X-ray Transients |
R.M. Hjellming. 1997, In IAU Colloquium 163, Accretion Phenomena and Related Outflows, A.S.P. Conf. Series, 121, Ed. D.T. Wickramasinghe, G.V Bicknell, and L. Ferrario, pp. 53-62 |
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The Black Hole X-ray Transient GRO J1655-40 |
If you want to see a sequence of 18 cm VLBA images of the superluminal radio jets of GROJ 1655-40, click on IMAGES |
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The Interacting Binary Star System RY Scuti |
If you want to see VLA radio and infra-red images of the circumstellar emission around the interacting binary system RY Scuti, click on Radio and IR Images |
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Radio and X-ray Flaring Events in X-ray Nova Ophiuchi 1993 |
Reference: Hjellming, R.M., Rupen, M.P., Shrader, C.R., Campbell-Wilson, D., Hunstead, R.W., and McKay, D.J. 1996 Ap. J. Letters, 470, L105-L10. |
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A Unified Model for the Radio and Optical Images and Spectra of Nova V1974 Cyg 1992 |
A paper prepared for the June-July 1995 conference at Keele. Reference: Hjellming, R.M. 1996, Cataclysmic Variables and Related Objects, Eds. A. Evans and Janet H. Wood (Kluwer Academic Publishers: Dordrecht), 317-320. To see the preprint of this paper click on Keele Proceedings Paper |
A Unified Model Approach to Interpreting Radio and Optical Images and Spectra for Classical Novae |
A invited paper presented at the July 1995 Barcelona Conference. Reference: Hjellming, R.M. 1996, Radio Emission from the Stars and the Sun, Ed. A.R. Taylor and J.M. Paredes, Pub. Astron. Soc. Pacific Conference Series, Volume 93, 174-181. To see the preprint of this paper click on Barcelona Proceedings Paper |