December 1997

Personal Details

Name:Alastair Grey GUNN
Address (work): University of Manchester
Nuffield Radio Astronomy Laboratories
Jodrell Bank, Lower Withington, Nr Macclesfield
Cheshire SK11 9DL
Telephone (work): +44 (0)1477 571321
Facsimile (work): +44 (0)1477 521618
Date of Birth: 21/4/67
Nationality: British
Marital Status: Single
Driving Licence: Full/Clean


1979-1985 Oxclose Comprehensive School
Washington, Tyne & Wear, UK
1985-1988 University of Wales, University College Cardiff, UK
Department of Astronomy (now known as UWCOC)
1989-1990 University of Manchester, UK
Nuffield Radio Astronomy Laboratories, Jodrell Bank
1990-1992 University of Leicester, UK
Department of Physics and Astronomy
1992-1995 Armagh Observatory, Armagh
N. Ireland, UK


GCE `O' level1983 9 Subjects: Mathematics, Additional Mathematics, Physics
Chemistry, Biology, English Language, English Literature, Art, Geography
GCE `A' level1985 3 Subjects: Mathematics, Physics, Chemistry
BSc. (Hons.) Degree1988 Astrophysics (University College Cardiff)
Research project on the Energy Distribution in the Cosmic Microwave Background
Research Supervisor: M. J. Disney
MSc. Degree1991 Radio Astronomy (University of Manchester)
Research project on Radio Interferometric Mapping of Extended Structure in Quasars
Research Supervisor: R. E. Spencer
PhD. Degree1995 Astrophysics (Queen's University of Belfast)
Research project on the Environments of Active Close Binary Stars
Research Supervisor: J. G. Doyle

Other Awards and Distinctions

Fellowship Royal Astronomical Society elected 1994
First Aid Certificate HSE Reg. No. 1203/92 8th January 1998

Professional Referees

Dr J G Doyle
Armagh Observatory
College Hill
Northern Ireland
BT61 9DG
Fax: +44 1861 527174
Tel: +44 1861 522928
Dr R E Spencer
Jodrell Bank
Lower Withington
Nr Macclesfield
Cheshire SK11 9DG
Fax: +44 1477 57161
Tel: +44 1477 571321
Dr V Migenes
VSOP Project
National Astronomical Observatory
Osawa 2-21-1
Tokyo 181
Fax: +81 422 34 3869
Tel: +81 422 34 3876

Positions of Responsibility

  • [1] Irish Astronomical Journal. In 1994 I was appointed as the Assistant Editor for the Irish Astronomical Journal. I was instrumental in the complete overhaul of the IAJ's publication strategy and a change of the style, content and format of this international main-stream astronomical research journal. The IAJ's success continues under a tight editorial budget and has gained renewed support from around the world over recent years. My chief responsibilities are the collection, proof-reading and electronic formatting of journal submissions (using LaTeX running under Unix systems), the allocation of professional referees from referee databases, liason with authors (particularly over points of text/figure quality), liason with subscribers, style and content quality control, final typesetting of the entire journal, final proof-reading, the maintenance of subscriber databases, journal indices and abstracts, the production and maintenance of the IAJ's WWW site using HTML and the shipment of journals and other products to subscribers.
  • [2] SSG. Since September 1996 I have been a member of the STARLINK Software Strategy Group for Radio and Millimetre Astronomy which advises the STARLINK project on the software needs of the UK astronomical community.
  • [3] Committees. I am on local committees at NRAL Jodrell Bank overseeing VLBI/MERLIN integration, Publications and Publicity and Web Site Development.
  • [4] Friend of VLBI. My current position at Nuffield Radio Astronomy Laboratories as ``Friend of VLBI'' involves all aspects of observing support at an international level. My duties involve the overview of technical equipment, the scheduling and preparation of observing programs for investigators all over the world, ensuring the simultaneity and coherence of VLBI observations performed at Jodrell Bank with those around the globe, the collection and analysis of local calibration data, the collection of observing logs and reports for international observers and the shipment of data tapes and other equipment. I also act as the first point of call for VLBI principle investigators and for the press on matters of intercontinental observing at Jodrell Bank.

National & International Links

During the course of my research I have been involved in collaborative projects with staff at the Armagh Observatory (UK), Nuffield Radio Astronomy Laboratories (UK), University of Sussex (UK), Australia Telescope National Facility (Australia), Lowell Observatory (USA), Michigan State University (USA), Athens University (Greece), VSOP Project (Japan) and Carter Observatory (New Zealand).

Academic Experience

  • [1] BSc Degree. My first degree at University College Cardiff was in Astrophysics. This gave me a good introduction to theoretical and practical physics and astronomy with heavy emphasis on mathematical analysis. Subjects studied were pure mathematics, physics, and applied mathematics. More specialized fields covered were mathematical physics, thermal physics, special and general relativity, stellar astrophysics, the interstellar medium, planetary science, galactic and extragalactic astronomy and cosmology. I submitted a final year research dissertation as part of the degree requirements. This was entitled Novel Energy-Distribution Analysis of the Cosmic Microwave Background.
  • [2] MSc Degree. Further to my first degree I undertook an MSc Degree by research in Radio Astronomy at Nuffield Radio Astronomy Laboratories, Jodrell Bank. This involved further study of more specialized theoretical and practical fields including; FFTs and the theory of image analysis, radio receivers and observational techniques, advanced EM theory, plasmas and radiation mechanisms, galactic radio sources, pulsars, cosmology, normal and active galaxies, digital signal processing and interferometry/aperture synthesis. In addition to the course material a technical project was undertaken to provide familiarity with electronics, advanced radio-frequency engineering, digital techniques and practical radio astronomical techniques. My final MSc thesis was entitled Low Frequency Mapping of Compact Steep-Spectrum Sources. This research project involved analysis of radio interferometric data using standard image restoration techniques. This work provided valuable insight into the nature and physical conditions of a compact steep-spectrum radio sources. On completion of my MSc I was employed in research at Leicester University on the analysis of radio signals as they propagate through the aurora in the high-latitude ionosphere.
  • [3] PhD Degree. I began studying for my PhD Degree in October 1992 at Armagh Observatory, registered as a full-time research student at Queen's University of Belfast. During my time at Armagh I studied the environments of active close binary systems (RS CVns and Algols) using optical and radio observations. I have also performed theoretical modeling of stellar convection zones. In September 1995 I submitted my thesis, which was entitled Environments of Active Close Binary Stars to the Queen's University of Belfast and was awarded the degree in November 1995.

Practical Experience

  • [1] Observations. I have gained valuable experience of practical astronomical observations, both in the optical and radio, having observed with the William Herschel Telescope (La Palma), the Anglo-Australian Telescope (Australia), the Coude Auxiliary Telescope (ESO, Chile), the John Hall Telescope (Lowell Observatory, USA), the 1.3-m MDM McGraw-Hill Telescope (Kitt Peak, USA), the CTIO 4-m Telescope (CTIO, Chile), the ATNF Compact Array (Australia), the VLA (Socorro, USA) and the Mk III/IV and VLBA VLBI recording systems at NRAL, Jodrell Bank. I have also been responsible for the reduction and analysis of the data collected on these instruments.
  • [2] Computing. I have gained much computing experience during my years of study. I have become a competent programmer in standard FORTRAN. I am capable of using Unix, VMS/DCL, and MS-DOS operating systems in a windows environment on both mainframe computers and PCs. In addition I have a great deal of experience in computing solutions to data handling and analysis. I am conversant with most starlink applications software, particularly DIPSO and FIGARO, and have made extensive use of the software packages IRAF, AIPS and IDL. I have a very good knowledge of TeX and LaTeX programming, having used this to produce style files etc. for the Irish Astronomical Journal and other projects. I am conversant with other word processing, desk top publishing and database software. I am also experienced in the advanced use of HTML, CGI, perl and Java scripts for the production of professional quality WWW sites.
  • [3] Teaching. I have had experience in teaching mathematics, physics and astronomy at undergraduate level and been responsible for a number of experiments in undergraduate physics laboratories; directing experiments, trouble-shooting and marking laboratory notebooks. I have also given popular astronomy courses at further education establishments.
  • [4] General. I have gained further valuable experience writing reports, literature reviews, observing proposals and theses. I have also written articles and news items for the popular press including The Daily Telegraph, New Scientist, Astronomy Now, Astronomy & Space Magazine and Clocks Magazine etc. I am currently involved in writing a series of popular astronomy articles for Sky & Telescope magazine. I am well practiced in presenting seminars of my work, covering the important points concisely and correctly. Necessarily I have gained the experience to carry out extensive searches of relevant literature and communicate their principles to the reader.

List of Publications

Scientific Research Papers
  1. A & A, 1994, 285, 157
    An Optical Flare on YZ Canis Minoris,
    Gunn A. G., Doyle J. G., Mathioudaki, M., Avgoloupis S.
  2. A & A, 1994, 285, 489
    High Velocity Evaporation During a Flare on AT Microscopium,
    Gunn A. G., Doyle J. G., Mathioudakis M., Houdebine E. R., Avgoloupis, S.
  3. CSW8, 1994, ASP 64, 702
    Eclipse Observations of Active Binary Systems,
    Gunn A. G., Doyle J. G., Houdebine, E. R.,
    in Cool Stars, Stellar Systems, and the Sun, J-P. Caillault (ed), Proceedings of the 8th Cambridge Workshop, ASP Conference Series Volume 64, p702.
  4. A & A, 1994, 291, 847
    Interferometer Observations of RS Canum Venaticorum Binaries,
    Gunn A. G., Spencer R. E., Abdul Aziz H., Doyle J. G., Davis R. J., Pavelin, P. E.
  5. IAJ, 1995, 22(1), 31
    An Energetic Flare on AT Microscopium,
    Gunn A. G., Doyle, J. G.
  6. A & A, 1996, 305, 146
    Cross-Correlation Radial Velocities of Chromospherically Active Binaries,
    Gunn A. G., Hall J. C., Lockwood G. W., Doyle, J. G.
  7. IAJ, 1996, 23(1), 33
    Re-investigation of Rotation-Activity Relations using Radio Luminosities,
    Gunn A. G.
  8. RESS, 1996, ASP 93, 321
    Radio Eclipse Imaging of CF Tucanae,
    Gunn A. G., Migenes V., Doyle J. G. Spencer, R. E.,
    in Radio Emission from the Stars and Sun, A. R. Taylor & J. M. Paredes (eds), ASP Conference Series Volume 93, p321.
  9. IAJ, 1996, 23(2), 137
    Environments of Active Close Binary Stars,
    Gunn A. G.
  10. CSW9, 1996, ASP 109, 649
    Environments of Active Binaries,
    Gunn A. G., Doyle J. G.,
    in Cool Stars, Stellar Systems, and the Sun, R. Pallavicini & A. K. Dupree (eds), Proceedings of the 9th Cambridge Workshop, ASP Conference Series Volume 109, p649.
  11. A & A, 1997, 318, 60
    Environments of Active Close Binaries I: ER Vulpeculae,
    Gunn A. G., Doyle J. G.
  12. A & A, 1997, 319, 211
    Environments of Active Close Binaries II: GK Hydrae and TY Pyxidis,
    Gunn A. G., Doyle, J. G., Houdebine E. R.
  13. MNRAS, 1997, 287, 199
    Radio and Extreme-ultraviolet Observations of CF Tucanae,
    Gunn, A. G., Migenes V., Doyle J. G., Spencer R. E.
  14. IAJ, 1998, 25(1), 33
    A Non-empirical Rotation-Activity Relation for Active Binaries Using Radio Luminosities,
    Gunn A. G.
  15. MNRAS, 1998, 296, 150
    On the Rotation-Activity Correlation for Active Binary Stars,
    Gunn, A. G., Mitrou C. K., Doyle J. G.
  16. CSW10, 1998, ASP 154, 1257
    On the Rotation-Activity Correlation in Active Binaries,
    Gunn A. G., Mitrou, C. K., Doyle J. G.,
    in Cool Stars, Stellar Systems, and the Sun, R. A. Donahue & J. A. Bookbinder (eds), Proceedings of the 10th Cambridge Workshop, ASP Conference Series Volume 154, p1257.
  17. A & A, 1999, 341, 527
    Evidence for Large-scale, Global Mass Inflow and Flaring on the Late-type Fast Rotator, BD+22 4409,
    Eibe M. T., Byrne P. B., Jeffries R. D., Gunn, A. G.
  18. MNRAS, 1999, 304, 611
    Eclipsing Behaviour of the Radio Emission in the Algol-type Binary V505 Sagittarii,
    Gunn A. G., Brady P. A., Migenes V., Spencer R. E., Doyle J. G.
  19. SSA, 1999, ASP 158, 178
    On the Determination of Spot Parameter in Active Late-type Stats,
    Zboril M., Byrne P. B., Amado P. J., Gunn A. G.,
    in Solar and Stellar Activity: Similarities and Differences, C. J. Butler & J. G. Doyle (eds), Proceedings of a Meeting held in Armagh, N. Ireland, 2-4 September 1998, ASP Conference Series Volume 158, p.178.
Popular Articles
  1. Clocks, September 1993, 16(4), 50
    Armagh's Longcase Regulators,
    Gunn A. G.
  2. IAJ, 1996, 23, 198
    Astronomical Clock's at Armagh Observatory,
    Gunn A. G.
  3. The Daily Telegraph, 5th February 1997, 44052, 14
    The Telescope That's Bigger Than Earth,
    Gunn A. G.
  4. Astronomy & Space, August 1997, 42
    Return to Mars,
    Gunn A. G.
  5. Astronomy Now, October 1997, 11(10), 6
    Satellite Observes Twisted Quasar Jet,
    Gunn A. G.,, Garrington S. T.
  6. Astronomy Now, November 1997, 11(11), 52
    Armagh Astronomy,
    Gunn A. G.
  7. Astronomy Now, January 1998, 12(1), 70
    But You're An Astronomer!,
    Gunn A. G.
  8. Astronomy Now, February 1998, 12(2), 6
    Bursts from a Milky Way black hole,
    Gunn A. G.
  9. Astronomy Now, May 1998, 12(5), 5
    A Bull's Eye for MERLIN and the Hubble,
    Gunn A. G.
  10. Astronomy & Space, July 1998, 24
    The World's Largest Radio Telescopes,
    Gunn A. G.
  11. The Independent on Sunday Review, 13th September 1998, 449, 52
    Ear's To The Skies,
    Gunn A. G.
Small Items
  1. New Scientist, In Brief, 30 October 1992, 136, 11
    Astronomy Theme,
    Gunn A. G.
  2. ATNF Newsletter, 1996, 29, 11
    Intra-binary Emission in V505 Sgr,
    Gunn A. G., Doyle J. G.

General Background

I am a keen musician and take my influence and enjoyment from many sources. I have been a freelance tutor of the classical guitar for many years, teaching in many styles of guitar playing including Spanish, jazz, blues, folk and rock. I also write my own compositions for guitar and use these as examples in my teaching. Whenever possible I try to attend recitals and musical concerts of all forms of music.

I have spent some time working in the entertainments business and at one time was a Stage Crew Manager for an entertainments venue. My duties involved the organisation of a team of technicians who constructed and ran various equipment for rock concerts and other events, hospitality of guests, and the help with backstage arrangements. I also took part in the organisation of conferences and the arrangement of security staff and was seconded to external venues. I gained experience of organisational responsibilities and learnt how to communicate my needs to people firmly but politely. I also acted as president and treasurer of a music appreciation society and have been employed as a disc jockey. I believe all these experiences have strengthened my inter-personal skills.

I am an avid reader of both factual and fictional publications. I enjoy exploring books on history, travel, science and philosophy, religion and mythology, medicine, and language and I am fascinated by the subjects of palaeontology and anthropology. I take much of my reading enjoyment from imaginative fiction but also like novels set in an historical context. I am particular interested in Victorian and Edwardian ghost stories.

In addition to reading I spend much of my spare time writing on scientific, philosophical and cultural topics. I write many short stories and poems and have several novels in the pipeline. I am currently in the process of writing a series of popular astronomy essays, used in my teaching of a local astronomy course, which I hope will be published in some small-press magazine and may eventually form the basis of an elementary astronomy textbook. Also, the notes and examples which I use to tutor classical guitar will become a self-learn book and reference source for guitar players.

I have enjoyed what time I have been able to devote to my involvement with the Irish Astronomical Journal. Through my duties as {\it Assistant Editor} I have gained a good capacity for organisational and communicative skills. My involvement has given me a keen insight into the running of a scientific publication and given me excellent proof-reading and editorial skills.

For exercise I enjoy regular swims, play badminton and take long hill walks whenever possible.

Research Interests

  • [1] Eclipse Imaging of Active Binaries

    One of the objectives of my PhD thesis research was to investigate the existence of coronal structures around active binary systems known as RS CVn stars. RS CVn stars are characterized by the existence of Ca II H & K emission lines and by a sinusoidal modulaton of brightness in late-type systems (Hall 1976). Their characteristics have been widely attributed to surface activity in the form of cool star-spots with an overlying active chromosphere. Even with the plethora of recent observations of these systems we are still far from understanding the basics of flare production and coronal structure or the effects of binarity. Recently evidence has been accumulating for the existence of large, cool structures in the outer atmospheres of these stars, similar in characteristics to solar coronal mass ejections or prominences (e.g. Scaltriti et al. 1993). The high flare frequencies of such stars coupled with these co-rotating coronal features suggests that high rates of mass-loss may be effecting both the stellar evolution and the local interstellar medium.

    Questions which were addressed this research included a) are such transient large-scale structures a common feature for RS CVn systems? b) is magnetic activity, through mass-loss, a key parameter in determining the evolution of such systems? c) what is the contribution of mass to the interstellar medium?, and d) what are the physical properties and evolutionary timescales of cool structures in stellar atmospheres?

    The approach taken in my thesis research was to select a small sample of RS CVn systems which undergo total or partial eclipses. These systems are powerful tools for investigating coronal and chromospheric properties of active stars since a) it is sometimes possible to completely isolate the component spectra in the usually double-lined RS CVn spectrum, and b) the occultation of a cool companion's outer atmosphere reveals plasma structures out to many stellar radii. In systems with greatly differing spectral types the blue continuum of the hotter star shines through the corona of the cooler star around primary eclipse revealing opaque structures in the Ca II resonance lines. Systems with similar components are usually of later type so observations of the Halpha, Na I D1/D2 and He I D3 lines can be used. By using a series of high-resolution spectra across both primary and secondary eclipses it is possible to ``image'' the coronae of these active stars and place some constraints on the size, positions, timescales and physical properties of the cool structures (see Hall & Ramsey 1992).

    Data were collected on several high-resolution spectrographs including the UES (William Herschel Telescope) and the UCLES (Anglo-Australian Telescope). The modelling of a time series of spectra involves determining the contribution of each component to the binary spectrum and comparing the lines of interest to a suitable non-active synthetic spectrum. This method yields an estimate of the excess absorption or emission due to extra-photospheric structures. Analysis of the motion of these excess features and the application of simple radiative transfer techniques allows a model of the coronal condensations to be formulated.

    I was also involved in several related fields of research during the course of my thesis work. Firstly in order to follow the progress of RS CVn eclipses it was necessary to perform follow-up observations and confirm or refute the published orbital ephemerides of the sample of RS CVn stars. This work involved the development of a cross-correlation technique for measuring binary radial velocities from low-resolution spectra. I have also extended the concept of eclipse imaging into the radio domain where I have attempted to observe the variability that would be expected from large radio coronae around active eclipsing binaries. I have also become interested in the rotation-activity correlation in late-type evolved binaries and have begun formulating a theoretical relationship between activity level and rotation based on models of the stellar interior (see Sections 3 & 4).

  • [2] Extended Material Around Active Binaries

    I hope to continue my research into the environments of active close binaries in the future. Much remains to be done in this burgeoning field. The techniques of spectral subraction (see Barden 1985) and eclipse imaging have been invaluable in recent years and proved the existence of coronal structures around late-type active binaries. Such systems consist of a wide variety of stars from cool M-dwarfs to A-type main-sequence, subgiant and giant stars. It is therefore possible to extend my work on magnetic activity over a broad range of spectral types and stellar masses. The effects of binarity on the production of activity has not yet been investigated thoroughly even for individual systems.

    Many RS CVn systems are known to exhibit dramatic changes in orbital period which are possibly due to mass-loss or energetic mass-transfer events. Evidence for these phenomena is already widely accepted. Low-resolution spectroscopy and photometric studies are essential for a proper investigation of the orbital properties of many RS CVn systems. Once this is achieved and the relative positions of the eclipsing components of RS CVns are well-known, high-resolution spectroscopy of activity sensitive lines will reveal the coronal signatures of a broad range of RS CVn systems. I hope that by widening the sample of systems I have studied at optical wavelengths and perhaps by performing observations in the UV and IR regions a fuller understanding of RS CVn environments and their interaction with the local ISM will be forthcoming. I intend to continue both my low-resolution work to confirm binary ephemerides and my high-resolution investigation of their environments.

  • [3] The Radio Emitting Environments of Active Binaries

    During my thesis research I was also able to apply my knowledge of radio interferometric techniques to the study of the coronal environments of active binary stars. Despite considerable observing effort over recent years we are still far from understanding the detailed behaviour of active stars in the radio domain. It is believed that radio emission occurs via gyro-synchrotron radiation from mildly relativistic electrons in the high-temperature regions of coronal magnetic loops. The details of how and where radio emission arises is still a mystery (see Drake et al. 1992).

    VLBI observations have had some success in deciphering the extent of radio magnetospheres around RS CVns. Some observations have shown the existance of structures on the scale of a few milli-arcseconds which corresponds to many stellar radii (Trigilio et al. 1993). This view is consistent with the optical evidence suggesting huge areas of coronal emission. A recent VLA study of the RS CVn system V471 Tauri (Patterson et al. 1993) showed a clear radio eclipse that suggested a region of mass-transfer between the two components. A comprehensive study of the eclipsing system ER Vulpeculae (Rucinski 1992), also with the VLA, showed no periodic behaviour of the radio emission with orbital period. Linsky & Gary (1983) also failed to see any conclusive modulation caused by eclipsing behaviour in YY Geminorum.

    With colleagues at the Australia Telescope National Facility I investigated whether eclipsing RS CVn sytems show evidence of radio modulation correlated with orbital phase. This is analogous to the technique of eclipse imaging in optical spectroscopy. All results to date have indicated that the radio coronae of RS CVns may easily envelope the entire binary system and therefore not display eclipsing behaviour. Furthermore regions of intra-binary radio emission were found in both an Algol and RS CVn star. This has important implications for the environments of such systems in general. I hope to pursue my research in the field of radio interferometry by searching for radio modulations and modeling the data obtained from multi-frequency observations.

  • [4] Rotation-Activity Correlations in Evolved Binaries

    During the course of my PhD studies I also became interested in the rotation-activity correlations reported for late-type active stars, including the RS CVn systems. A possible correlation between rotation and chromospheric activity was first pointed out by Kraft (1967). The hypothesis is that late-type stars have magnetic fields generated by a dynamo mechanism and that the field generation depends partly on the forces produced by rotation and partly on the depth of the stellar convection zone. It is believed, and at least partly proven, that stars of later spectral types (that is with deeper convection zones) display stonger dynamo behaviour, and therefore chromospheric activity, for a given rotation period. Coronal relations have been reported by Walter & Bowyer (1981) for RS CVn systems, and by Pallavicini et al. (1981) for mostly single stars. Chromospheric relations were presented by Noyes et al. (1984).

    The dynamo theory predicts that the rotation rate and the convection zone properties should determine the level of activity and it has been difficult to formulate a parameter which encompasses both. The most widely used parameter is the Rossby number which is defined as the ratio of rotational period to convective turnover time. The problem with this approach is that the Rossby number is heavily dependent on the convection model used. Most authors have previously assumed a convection turnover timescale based on an empirical fit to colour measurements of a small sample of main-sequence single stars. This approach will not give adequate results for the RS CVn binaries since these systems are slightly evolved and therefore have highly variable convective envelopes. Also the effects of binarity on the properties of the convection zone are unknown.

    I have attempted to address this problem by constructing stellar convection zone models over a range of stellar masses and evolving them off the main-sequence to simulate the population of RS CVn binaries. Comparison of the evolution of the convection zone in this part of the HR diagram to published activity diagnostics will help in determining an empirical relationship for these systems. In the future I hope to continue this work by investigating the effects of binarity on the stellar models.


  1. Barden, S. C., 1985, ApJ, 295, 162.
  2. Noyes, R. W., et al., 1984, ApJ, 279, 763.
  3. Drake, S. A., Simon, T., & Linsky, J. L., 1992, ApJS, 82, 311.
  4. Pallavicini, R., et al., 1981, ApJ, 248, 279.
  5. Hall, D. S., 1976, in Multiple Periodic Variable Stars, IAU Coll. 29, W. S. Fitch (ed), Reidel (Dordrecht).
  6. Patterson, J., et al., 1993, PASP, 105, 848.
  7. Rucinski, S. M., 1992, PASP, 104, 1177.
  8. Hall, J. C., & Ramsey, L. W., 1992, AJ, 104, 1942.
  9. Scaltriti, F., et al., 1993, MNRAS, 264, 5.
  10. Kraft, R. P., 1967, ApJ, 150, 551.
  11. Trigilio, C., et al., 1993, MNRAS, 260, 903.
  12. Linsky, J. L., & Gary, P. E., 1983, ApJ, 274, 776.
  13. Skumanich, A., 1972, ApJ, 171, 565.
  14. Stauffer, J. R., & Hartmann, L. W., 1987, ApJ, 318, 337.
  15. Stauffer, J. R., et al., 1985, ApJ, 289, 247.
  16. van den Heuvel, E. P. J., & Conti, P. S., 1971, Science, 171, 895.
  17. Walter, F. M., & Bowyer, S., 1981, ApJ, 245, 671.