Messenger No. 39 (March 1985)
New infrared photometer and f/35 chopping secondary at the 3.6 M telescope
Moorwood, A.; van Dijsseldonk, A.
AA(European Southern Observatory, Garching, West Germany), AB(European Southern Observatory, Garching, West Germany)
The design and operation of the f/35 chopping secondary mirror and IR detector system installed on the 3.6-m telescope at ESO in November 1984 are reported and illustrated with diagrams and photographs. The 33-cm-diameter chopping mirror is driven by magnetic actuators to provide either square-wave chopping or a linear sky sweep (with rise time 5 ms and end-position stability 0.5 percent of amplitude up to 2 arcmin of sky) and is equipped with an opposition-driven compensator plate to suppress vibrations. The photometer comprises both InSb and bolometer detectors and a TV-camera acquisition and guidance system and offers 1-sigma limiting-magnitude improvements of 0.2-0.8 mag (using a 7.5-arcsec aperture for 30 min) over the previous f/8 system. A similar photometer is being built for use on the 2.2-m telescope.
AS 338 in Outburst, or how i Found my "PET Symbiotic"
Until some months ago, I used to envy those of my colleagues who were always talking and writing with tremendous enthusiasm about their favourite object. My recent observations of the symbiotic star AS 338 enable me now to tell an exciting story as weil.
Tentative Time-table of Council Sessions and Committee Meetings in 1985
A near infrared survey of the southern Galactic plane
AA(Meudon, Observatoire, Meudon, Hauts-de-Seine, France)
Preliminary results of a near-IR survey of the southern Galactic plane, conducted at 2.2 microns using an N2-cooled InSb detector at the Cassegrain focus of the 60-cm telescope at Sao Paulo, with followup JHKLM photometry using the standard IR photometer on the 1-m telescope at ESO, are reported and illustrated with graphs. A total of over 1500 objects has been detected in the region between Car and Sco; 338 were selected for followup photometry; and about two thirds of those have not been identified with cataloged stars and comprise mainly late-type dust-shell variables and giants/supergiants. The need for a deep complete ground-based near-IR survey is indicated.
Epehtein, N., Matsuura O. T., Lepine, J. R. D., Braz, M.A, Pieazzio, E.,
Marques Dos Santos, P., Boseolo, P., Le Bertre, T., Roussel, A.,
Turon, P.: 1985, Astron. Astrophys. Suppl. Ser., submitted.
Grasdalen, G. L., Gehrz, R. D., HackweIl, J.A., Castelaz, M., Gullixson,
C.: 1983, Astrophys. J. Suppl. Ser., 53,413.
Kleinmann, S. G., Payne-Gaposehkin, C., 1979: Earth and Extraterr.
Sei., 3, 161.
Neugebauer, G., Leighton, R.B., 1969: Two Mieron Sky Survey,
Nguyen-Q-Rieu, Epchtein, N., Le Bertre, 1.,1983: The Messenger No.
Price, S. D., Walker, R. G., 1976, The AFGL Four Color Infrared Sky
List of Preprints Published at ESO Scientific Group
Coordinated multiband observations of stellar flares
Rodono, M.; Foing, B. H.; Linsky, J. L.; Butler, J. C.; Haisch, B. M.; Gary, D. E.; Gibson, D. M.
AA(Catania, Universita, Catania, Italy), AB(European Southern Observatory, La Silla, Chile), AC(Joint Institute for Laboratory Astrophysics, Boulder, CO), AD(Armagh Observatory, Armagh, Northern Ireland), AE(Lockheed Research Laboratories, Palo Alto, CA), AF(California Institute of Technology, Pasadena, CA), AG(New Mexico Institute of Mining and Technology, Socorro, NM)
The March 28, 1984 flare of AD Leo is characterized on the basis of observations obtained over the spectral range from 200 nm to 20 cm using the IUE, the VLA, and four ESO telescopes as part of a coordinated multiband international campaign. The data are presented graphically and discussed, with consideration of faint negative K-band events observed simultaneously with the optical flare; an H-alpha precursor with longer energy-release relaxation than in the U continuum; and remarkably enhanced UV continuum, Mg II doublet, and 260-nm Fe II blend during the last secondary optical peak.
Byrne, P. B. and Radom), M., (eds.) 1983, Activity in Red Owarf Stars,
lAU Coll. 71, Reidel, Dordrecht.
Haisch et al., 1983, Astrophysical Journal 267, 280.
Rodono et al., 1983, Comm. 27, lAU, Inf. Bull. Var. Stars, No. 2322,
Rodono et al., 1984, Coordinated IUE and Ground Based Observations
ofActive Stars, 4th European IUE Conterence, ESA SP - 218,
Visiting Astronomers (April 1 - October 1, 1985)
Serendipitous Discovery of a High Redshift Quasar
Within the framework of our survey of carbon stars (C stars) in dwarf spheroidal galaxies (Azzopardi and Westerlund, 1984, The Messenger 36, 12), the Carina galaxy was observed on November 2, 1983 at La Silla. A very good quality 2-hourexposure plate was obtained at the prime focus of the 3.6 m telescope, using the triplet corrector, the Hoag Grism R35 and a GG435 filter (see Breysacher and Lequeux, 1983, The Messenger 33,21). The GG435 filter, in combination with the IIIa-J emulsion in order to reduce the instrumental spectral domain to the useful range 4350-5300 A, allows one to reduce the crowding. The plate was searched systematically using a binocular microscope with small magnification. This allowed us to identify 6 out of the 7 C stars listed by Mould et al. (1982, Astrophysical Journal 254, 500) plus 4 new candidates and one dubious (Azzopardi, Lequeux and Westerlund, 1984, ESO preprint No. 345).
Circumstellar shells in the Large Magellanic Cloud
AA(Koenigstuhl, Landessternwarte, Heidelberg, West Germany)
The detection of a ring nebula around the LMC S Dor variable R 127 in observations with a CCD detector and 2-nm-wide H-alpha filter on the 1.5-m telescope at ESO in January 1984 is reported. The problems involved in detecting nebulae in the LMC are reviewed, and images and graphs are provided.
Chu, Y.-H., Lasker, S. M.: 1980, Publ. Astron. Soc. Pacific 92, 730.
Davidson, K., Dufour, R.J., Walborn, N. R., Gull, T. R.: 1984, lAU Symp.
No. 105, Reidel, eds. A. Maeder and A. Renzini, p. 261.
Lund, G., Ferlet, R.: 1984, The Messenger, No. 36, 2.
Stahl, 0., Wolf, S., Klare, G., Cassatella, A., Krautter, J., Persi, P.,
Ferrari-Toniolo, M.: 1983, Astronomy and Astrophysics 127, 49.
Thackeray, A. D.: 1950, Monthly Notices of the Royal Astronomical
Society 110, 524.
Walborn, N. R.: 1982, Astrophysical Journal 256, 452.
Wolf, S., Stahl, 0.: The Messenger, No. 33, 11.
A Possible Nonlinearity in IDS / Image Dissector Scanner / Data
Most of the users of the Image Dissector Scanners mounted on the Boiler & Chivens Cassegrain spectrographs on La Silla will be aware of the high count rate nonlinearity of the IDS. The typical figure for this saturation effect is a 10 per cent loss at count rates in excess of some 2,000 detected events per channel per second. For a linear dispersion of 1.7 Aper channel (171 Aper mm grating) this corresponds to a 10 mag star at the 3.6 m and an 8 mag star at the 1.5 m telescopes. In the following I will report on another nonlinearity effect present at very low light levels, i.e. for count rates below 100 counts per second and channel, and discuss some of the possible sources and implications.
The local stellar environment (LSE) - The B emission-line stars
AA(Paris, Observatoire, Paris, France)
The LSE of Be stars is characterized in a review of theoretical models and visual and FUV observations, summarizing the reports of Underhill and Doazan (1982) and Thomas (1984). Topics examined include the variable cool LSE proposed on the basis of visible observations only, the variable hot rapidly expanding LSE seen in the FUV, the roles of variable mass flux and/or variable nonradiative energy flux in the variability of Be stars, a tentative empirical decelerated-outflow model accounting for the visible and FUV features, and ongoing observational studies (using IUE, Exosat, and several ESO instruments) of the nonthermal properties of the stellar subatmosphere. Typical C IV line profiles for the Be stars HD 200120 and HD 138749 are shown.
The multi-faceted active galaxy PKS 0521 - 36
Danziger, I. J.; Shaver, P. A.; Moorwood, A. F. M.; Fosbury, R. A. E.; Goss, W. M.; Ekers, R. D.
AA(European Southern Observatory, Garching, West Germany), AB(European Southern Observatory, Garching, West Germany), AC(European Southern Observatory, Garching, West Germany), AD(European Southern Observatory, Garching, West Germany), AE(Groningen, Rijksuniversiteit, Groningen, Netherlands), AF(National Radio Astronomy Observatory, Socorro, NM)
The southern active elliptical galaxy PKS 0521 - 36 is characterized in a review of observational investigations. Consideration is given to the 20-kpc-long jet-like structure pointing northwest from the galaxy, the low-ionization-state filamentary structure to the east and southeast, the three nonstellar components identified in the nucleus, the radio structure and its correlation to the optical features, and the X-ray emission. A total H-beta emission of 9 x 10 to the 39th erg/s and an accumulating mass flow of 500 solar mass/yr are estimated.
Angel, J. R. P., Stockman, H. S., 1980. Ann. Rev. Astron. Astrophys.
Balick, B., Heckman, T. M., 1982. Ann. Rev. Astron. Astrophys. 20,
Bolton, J. G., Clarke, M. E., Ekers, R. 0., 1965. Aust. J. Phys. 18, 62?
van Breugel, W., 1981. Optical Jets in Galaxies, Proc. 01 Second ESOI
ESA Workshop, p. 63.
Danziger, I.J., Fosbury, R.A E., Goss, W. M., Ekers, R. 0.,1979. Mon.
Not. R. Astr. SOG. 188, 415.
Danziger, I.J., Bergeron, J., Fosbury, R.A.E., Maraschi, L., Tanzi,
E.G., Treves, A., 1983. Mon. Not. R. Astr. SOG. 203, 565.
Danziger, I.J., Fosbury, R. A. E., Goss, W. M., Bland, J., Boksenberg,
A, 1984. Mon. Not. R. Astr. SOG. 208,589.
Eggen, O. J., 1970. Astrophys. J. 159, L95.
Fabian, AC., Nulsen, P. E.J., 1977. Mon. Not. R. Astr. SOG. 180,479.
Fosbury, R. A E., 1982, ExtragalaGtiG Radio SourGes, lAU Symposium
Fosbury, R.A E., Tadhunter, C. N., Bland, J., Danziger, I.J., 1984.
Mon. Not. R. Astr. SOG. 208, 955.
Mills, B. V., Slee, O. B., Hili, E. R., 1960. Aust. J. Phys. 13, 676.
Nicholson, W., Penston, M.J., Murray, C.A, de Vegt, C., 1984. Mon.
Not. R. Astr. SOG. 208,911.
Schwartz, D.A, Ku, W. H. M., 1983. Astrophys. J. 266, 459.
Searle, L., Bolton, J. G., 1968. Astrophys. J. 154, L101.
Sol, H., 1983. Astrophysical Jets, Proceedings 01 Torino Workshop
Oct. 1982. D. Reidel. p. 135.
Ulrich, M.-H., 1981. Astron. Astrophys. 103, L1.
Westerlund, B. E., Stokes, N. R., 1966. Astrophys. J. 145, 354.
Observations of high redshift MG II and Fe II absorption lines in QSO spectra
Boisse, P.; Bergeron, J.
AA(Ecole Normale Superieure, Paris, France), AB(CNRS, Institut d'Astrophysique, Paris, France)
When the first absorption system was discovered in the spectrum of 3C191 by Burbidge et al. (1966) it was immediately realized that the analysis of aso spectra could bring a lot of information on the large-scale content of the universe. The path length to high redshift asos is so large that the line of sight towards such objects is likely to intersect galaxies and intergalactic clouds which will leave their signature in the spectrum. Although many questions remain yet unsolved today, some conclusions emerge from the increasing amount of data. It seems now weil established that among all systems, those containing sharp metal-rich absorption lines can be associated with intervening galactic haloes. Arguments are mainly of a statistical nature and come from a detailed study of the redshift distribution of the systems. This function appears to be compatible with absorption by randomly distributed clouds and, moreover, the systems tend to cluster in the same manner as galaxies (Young et al. 1982).
Bergeron, J., Boisse, P.: 1984, Astron. Astrophys. 133, 374.
Boisse, P., Bergeron, J.: 1985, Astron. Astrophys., to be published.
Burbidge, E. M., Lynds, C. R., Burbidge, G. R.: 1966,Astrophys. J. 144,
Robertson, J. G., Shaver, P.A., Carswell, R. F.: 1983, XXIV Colloque
International de Liege, ed. J.-P. Swings, p. 602.
Sargent, W. L. W., Young, P. J., Boksenberg, A., Tytler, D.: 1980,
Astrophys. J. Suppl. 42, 41.
Savage, B. D., de Boer, K. S.: 1981, Astrophys. J. 243, 460.
Tytler, D., Boksenberg, A., Sargent, W. L. W., Young, P., Kunth, D.:
1984, prepri nt.
Young, P. J., Sargent, W. L. W., Boksenberg, A.: 1982, Astrophys. J.
Suppl. 48, 455.
Nova MUSCAE 1983: Coordinated observations from X-rays to the infrared regime
Krautter, J.; Beuermann, K.; Oegelman, H.
AA(Koenigstuhl, Landessternwarte, Heidelberg, West Germany), AB(Berlin, Technische Universitaet, Berlin, West Germany), AC(Max-Planck-Institut fuer extraterrestriesche Physik, Garching, West Germany)
Observations of Nova Mus 1983 obtained since its discovery in January 1983 are summarized, with an emphasis on visual and IR photometry and spectroscopy performed at ESO. The data are presented graphically and characterized in detail. Nova Mus 1983 is classified as a fast nova with t3 = 40 d, Vmax = 7.0 mag, M(V) = -7.75, and distance 4.8 kpc. By 1984 the spectrum was dominated by strong nebular emission lines, including the forbidden coronal lines of Fe X at 607.4 nm and Fe XIV at 530.3 nm. The possible mechanisms responsible for the soft X-ray emission detected (at approximately constant count rates) by Exosat in April, July, and December 1984 are discussed.
On the problem of the luminous emission line stars
AA(Istituto di Astrofisica Spaziale, Frascati, Italy)
Superluminous emission-line stars in the Galaxy and Magellanic Clouds are characterized in a review of recent ESO optical and IUE UV observations. The data are presented graphically, and consideration is given to the emission lines most frequently observed, the high-resolution H-alpha profiles, the sharp variability of the S Dor variables, the smaller transient phenomena of P Cyg and Eta Car, and the role of circumstellar dust.
Andriesse, C.D., Dann, S.o., Viatti, R.: 1978, Mon. Not. R. Astr. Soc.
Bensammar, S., Guadenzi, S., Johnson, H.M., The, P.S., ZUiderwijk,
E.J., Viotti, R.: 1981, Effects of Mass Lass on Stellar Evolution, C.
Chiosi and R. Stalio eds., D. Reidel, Dordrecht, 67.
Bensammar, S., Friedjung, M., Muratorio, G., Viatti, R.: 1983, Astron.
Caputo, F., Viatti, R.: 1970, Astron. Astrophys. 7, 266.
de Jager, C.: 1980, The Brightest Stars, D. Reidel, Dordrecht.
Glass, I. S.: 1984, Mon. Not. R. Astr. Soc. 209, 759.
Gilmozzi, R., Viotti, R., Wolf, 0., Zickgraf, F.-J.: 1985, in prep.
Lamers, H.J., Korevaar, P., Cassatella, A.: 1984, Fourth European IUE
Conference, ESA SP-218, 315.
Mayall, MW.: 1969, J.R. Astr. Soc. Canada 63, 221.
Melnick, J., Ruiz, M.T., Maza, J.: 1982, Astron. Astrophys. 111, 375.
Muratorio, G., Friedjung, M., Viatti, R.: 1984, Proc. Fourth European
IUE Conference, Rome, 15-18 May 1984, ESA SP-218, p. 309.
Shore, S.N., Sanduleak, N.: 1984, Astrophys. J. Suppl. Series 55, 1.
Stahl, 0., Leitherer, C., Wolf, S., Zickgraf, F.-J.: 1984, Astron. Astrophys.
Stahl, 0., Wolf, S., de Groot, M., Leitherer, C.: 1985, Astron. Astrophys.
Suppl., in press.
Viotti, R.: 1969, xv Liege Colloquium Les Transitions Interdites dans
les Spectres des Astres, Universite de Liege, Val. 54, 333.
Viotti, R.; 1976, Astrophys. J. 204, 293.
Viotti, R., Altamore, A., Sarylak, M., Cassatella, A., Gilmozzi, R., Rossi,
C.: 1984, NASA IUE Conference.
Wolf, S., Stahl, 0.: 1982, Astron. Astrophys. 112, 111.
Wolf, S., Stahl, 0.: 1983, The Messenger, No. 33, 11.
Zanella, R., Wolf, S., Stahl, 0.: 1984, Astron. Astrophys. 137,79.
Rotation and activity of T Tauri stars
Bouvier, J.; Bertout, C.
AA(CNRS, Institut d'Astrophysique, Paris, France), AB(CNRS, Institut d'Astrophysique, Paris, France)
Techniques for determining the rotational velocities of faint stars are reviewed, and preliminary results from observations of 12 T Tau stars (six in the region of Rho Oph) obtained using the Coravel instrument (Benz and Mayor, 1980) on the 1.5-m Danish telescope at ESO during June 1984 are combined with published data on eight other T Tau stars (as well as selected RS CVn systems, dKe-dMe stars, and main-sequence G and K stars) and analyzed. Cross-correlation methods are shown to be more applicable to T Tau stars than those based on Fourier analysis. A log-log plot of the v sin i values determined by this technique versus published X-ray luminosities reveals that X-ray luminosity scales approximately with the square of the rotational velocity, consistent with dynamo models of surface activity in these objects.
Double emission and line absorption doubling in Mira stars: A new approach
Gillet, D.; Bouchet, P.; Ferlet, R.; Maurice, E.
AA(European Southern Observatory, Garching, West Germany), AB(European Southern Observatory, Garching, West Germany), AC(CNRS, Institut d'Astrophysique, Paris, France), AD(Marseille, Observatoire, Marseille, France)
Empirical models explaining the double H-alpha emission line and absorption-line doubling seen in the spectra of Mira variables are discussed on the basis of ESO coude echelle spectrometer observations of Omicron Cet (Gillet et al., 1983) and S Car (Gillet et al., 1985). Typical spectra are shown, and the strong absorption seen at the H-alpha wavelength in the blueshifted spectra is found to be apparent in nature, the result of geometric effects associated with the 70-80-km/s propagation of the shock front in the stellar atmosphere. The P-Cyg-type profiles of Ca II and Ti I and the profile of Fe I seen in the near IR just after maximum luminosity for S Car are found to originate near the photosphere and attributed to ballistic motions resulting from shock-wave propagation (rather than the presence of two components, as proposed by Wing, 1980).
Gillet, 0., Maurice, E., Baade, 0.: 1983, Astron. Astrophys. 128,384.
Gillet, 0., Maurice, E., Bauchet, P., Ferlet, R.: 1985, Astron. Astrophys.,
Hinkle, K. H., Scharlach, W. W. G., Hall, D. N.: 1984, Astrophys. J.
Suppl. 56, 1.
Lund, G., Ferlet, R.: 1984, The Messenger 36,2.
Jay, A.H.: 1947, Astrophys. J. 106,288.
Willsan, L.A.: 1976, Astrophys. J. 205, 172.
Wing, R. F.: 1980, Gurrent Problems in Stellar Pulsation Instabilities,
Eds. Fischei, 0., Lesh, J. R., Sparks, W. M., p. 533.
W Serpentis stars - A new class of interacting binaries
Strupat, W.; Drechsel, H.; Rahe, J.
AA(Remeis-Sternwarte, Bamberg, West Germany), AB(Remeis-Sternwarte, Bamberg, West Germany), AC(Remeis-Sternwarte, Bamberg, West Germany)
Spectroscopic and photometric observations of the interacting binary W Ser obtained at ESO in September 1984 with the IDS on the 1.52-m telescope and in the UVBRI system with the 1-m telescope, respectively, are reported. The data are presented graphically and characterized, with reference to the other objects placed in the W Ser classification by Plavec and Koch (1978). Features discussed include the unusual light curve, with a period increasing by 15 s/yr; UBVRI fluxes consistent with a 5-solar-radius F4III primary and a 3.5-solar-radius 3100-K 1-solar-luminosity M subgiant secondary; and an optical spectrum dominated by strong H Balmer, He I, and He II lines (with an inverse P Cyg profile for the 587.6-nm He I triplet). An evolutionary model is proposed in which W Ser has already passed through a rapid-mass-transfer stage (when the mass ratio reversed itself on a thermal Helmholtz-Kelvin time scale) and in which mass transfer from the formerly more massive component (in contact with its Roche lobe) continues.
Koch, R. H., Guinan, E. F.: 1978, IBVS 1483.
Lynds, C.R.: 1957, Ap.J. 126,81.
Plavec, M., Koch, R. H.: 1978, IBVS, 1482.
Visits to La Plata Observatory
La Plata Observatory will welcome visitors to ESO-La Silla that are willing to make a stop at Buenos Aires on their trip to Chile or on their way back. There is a nice guesthouse at the Observatory that can be used, for a couple of days or so, by astronomers interested in visiting the Observatory and delivering talks on their research work to the Argentine colleagues. No payments can, however, be made at present. La Plata is at 60 km from Buenos Aires. In the same area lie the Instituto de Astronomia y Fisica dei Espacio (IAFE), in Buenos Aires proper, and the Instituto Argentino de Radioastronomia (IAR). about 40 km from Buenos Aires on the way to La Plata. Those interested should contacl: Sr Decano Prof. Cesar A. Mondinalli, or Dr Alejandro Feinstein, Observatorio Astron6mico, Paseo dei Bosque, 1900 La Plata, Argentina. Telex: 31216 CESLA AR.