Messenger No. 17 (June 1979)
Mapping of galaxies at high radio frequencies.
AA(the Max Planck Institute for Radioastronomy in Bonn, FRG,)
Professional astronomers are sometimes asked the question of whether observations with radio telescopes are better than the "old-fashioned" optical observations? The answer is of course that they are equally valid: to understand the objects in the Universe, we must observe them over the widest possible spectral range. For this purpose, short-wavelength observations are now carried out from spacecraft, and in the other end of the spectrum we rely upon the ingenuity of the radio astronomers with their giant antennas. In this review, Dr. Richard Wielebinski of the Max Planck Institute for Radioastronomy in Bonn, FRG, gives examples of the important interaction between optical and radio observations for the study of nearby galaxies.
delta Crucis is variable!
Elst, E. W.
AA(the Royal Observatory at Uccle, Belgium)
During a recent visit to La Silla, Dr. Eric W. EIst of the Royal Observatory at Uccle, Belgium, discovered that one of the stars in the Southern Cross is variable. So are many other stars, but the present case is particularly interesting because the maximum amplitude in the lightcurve is only 0':'0061 The discovery is a powerful demonstration of the quality of the La Silla site and a tribute to the Bochum 61 cm telescope and its photometer.
Cluster hunt in the southern Milky Way.
Lodén, L. O.
AA(the Stockholm Observatory, Sweden,)
Most of the known stellar clusters in the Milky Way have been found because they contain conspicuous groupings ot relatively bright stars. Nobody .doubts, however, that there are many other clusters, in particular very loose ones, which are not known at present. But how to discover them and to prove that they are real physical entities? In this article, Dr. Lars Olof Loden from the Stockholm Observatory, Sweden, summarizes one aspect of a large investigation that has been underway for nearly two decades: finding new clusters in areas that are densely packed with stars.
Discovery of new Wolf-Rayet stars in the Magellanic Cloud.
Breysacher, J.; Azzopardi, M.
AA(ESO) AB(Observatoire de Toulouse,Franee)
As a result of a thorough seareh with the ESO GPO astrograph, the number of known Wolf-Rayet stars in the Small Magellanie Cloud has just been doubled (from 4 to 8). Drs. Jaeques Breysaeher (ESO) and Mare Azzopardi (Observatoire de Toulouse, Franee) also diseovered 17 new WR stars in the Large Magellanie Cloud. Slit speetra of these stars have been obtained with the 3.6 m teleseope and there is an indieation of a signifieant differenee between the WR stars in the Clouds and those in our own galaxy.
Azzopardi, M. and Breysacher, J.: 1979a, Astron. Astrophys. (in press).
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The 100th anniversary of the birth of Bernhard Schmidt.
The inventor of the so-calied "coma-free telescope" was born a hundred years ago, on March 30, 1879, as the son of a poor fisherman on the island of Nargen in the Baltic Sea near Reval in Estonia. Already as a child he experimented scientifically, and he lost his right arm, due to an explosion in his primitive laboratory.
0.5 arcsecond images with the Danish 1.5 m telescope on La Silla.
Andersen, J.; Niss, B.
AA(the Copenhagen Observatory,Denmark) AB(the Copenhagen Observatory,Denmark)
The 2.4 m Space Telescope will achieve (J'1 resolution in 1984. But what is the best possible angular resolution from a ground-based observatory? Recently, fantastic long-exposure plates were obtained with the Danish 1.5 m telescope at La Silla, proving at the same time the excellent performance of this new telescope and the quality of the ESO site. Drs. Johannes Andersen and Birger Niss from the Copenhagen Observatory, Denmark, tell the exciting story.
The problem of star formation - and what ten nights of sub-millimetre observations with the VLT could contribute to its solution.
Mezger, P. G.
AA(the Max Planck Institute for Radioastronomy in Bonn)
Astronomical observations are regularly carried out over the whole electromagnetic spectrum, from y-rays to low-frequency radio waves. There are few unexplored "holes", but one of these-in the neighbourhood of 1 mm-is exactly where we expect most of the radiation from stars during their early stages of formation. The VL T would be ideally suited for ground-based observations in the sub-millimetre range, because of its large surface and good angular resolution. Dr. Peter Mezger of the Max Planck Institute for Radioastronomy in Bonn explains how the VL T can make a very important contribution to the study of stellar formation.
European astronomers discuss the use of the Space Telescope.
With the publication of the Proceedings of the ESA/ESO Workshop on "Astronomical Uses of the Space Telescope", held in Geneva on February 12-14, 1979, it is now possible to better judge the interest of the European astronomical community in the Space Telescope. The Proceedings of course only represent the "official" part of the meeting. There were also lively discussions among the 186 participants and it is impossible to write them all down!
HD 101947 - the first very-long-period classical Cepheid in our galaxy?
Eichendorf, W.; Reipurth, B.
AA(the Astronomical Institute in Bochum,FRG) AB(the Copenhagen Observatory, Denmark)
The ESO observatory on La Silla is notjust a place where you go to observe-it is also an important meeting place for European astronomers. Many papers with co-authors from different institutes have resulted from encounters over a cup of tea and a "completo ". This was also the beginning of the long collaboration between Drs. Walter Eichendorf from the Astronomical Institute in Bochum, FRG, and BO Reipurth from the Copenhagen Observatory, Denmark. Over a period of several months, they continued to observe a star that later turned out to be unique among the Cepheids in our galaxy.
Sulfur dioxide and carbon disulfide in the Venus clouds.
Hua, C. T.; Courtès, G.; Doan, N. H.
AA(Laboratoire d'Astronomie Spatiale, Marseille) AB(Laboratoire d'Astronomie Spatiale, Marseille) AC(Observatoire de Lyon)
Exciting results were obtained trom the Pioneer Venus spacecraft as it reached our mysterious neighbour planet in late 1978. In contrast to our own lite-supporting, oxygen-rich atmosphere, that on Venus is dense, hot and poisonous. Spectroscopic observations near the atmospheric cut-ott at 3000 Awere recently made at La Silla by Drs. C. T. Hua and G. Courtes (Laboratoire d'Astronomie Spatiale, Marseille), together with Dr. N. H. Doan (Observatoire de Lyon), showing tor the tirst time that there may be carbon disultide in the Venus clouds, adding a compelling malodorous reason tor not going therel
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Hua, G. T. Gourtes, G., Doan, N. H., 1979, C. R. Acad. Sci., Paris, B 46, in press (19 March).
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First photographs of Andromeda and galactic clusters at 1950 Å.
Golay, M.; Huguenin, D.; Deharveng, M.
AA(Geneva Observatory) AB(Geneva Observatory) AC(LAS, Marseille)
The photographs shown in this note were taken on Oetober 30, 1978, with a eamera built by the Spaee Astronomy Laboratory of Marseille (LAS) and launehed in the stratospherie gondola of Geneva Observatory.
Cassegrain echelle spectrograph (CASPEC).
Le Luyer, M.; Melnick, J.; Richter, W.
AA(ESO Geneva) AB(ESO Geneva) AC(ESO Geneva)
The CASPEC figures prominently among the future, highly advanced auxiliary instruments for the ESO 3.6 m telescope. It will allow high-dispersion, spectroscopic observations of comparativeIy faint objects to be made in a reasonab/e amount of observing time. When it enters into operation in late 1980, it will become possible to analyse distant stars and nebulae in great detail. The CASPEC project is directed by Maurice le Luyer, Jorge Melnick and Wolfgang Richter from ESO Geneva.
Relative radial velocities of stars determined from GPO spectrograms.
AA(the Hoher List Observatory)
One of the first telescopes to be installed on La Silla was the GPO 40 cm astrograph. Although it is one of the "smallest" instruments at the ESO observatory, it is by no means less productive than the larger ones! On the contrary, the impressive results that have recently been obtained by Dr. Frank Gieseking of the Hoher List Observatory, near Bonn, proves the tremendous potential of this instrument. Thanks to the good accuracy of the measured radial velocities, large-scale investigations of stellar motions can now be carried out.
Assembly of the Coudé Echelle Spectrograph (CES).
AA(ESO Optics Section, Geneva)
The coude echelle spectrometer has al ready been described in the MessengerNo.11 of December 1977. It is a very high resolution spectrograph with a resolving power up to 100,000 fed by either the 3.6 m or the Coude Auxiliary Telescope (CAT). Henceforth it will be complemented by the CASPEC which will provide a resolving power of 20 to 60,000 (cf. page 27).
Television detector system development at ESO.
Crane, P.; Nees, W.
The traditional picture of an astronomer with a long beard, gazing through his telescope and solving the riddles of the Universe, is no longer true. First of all, the beard would all too easily get mixed up with the computer terminal keys and be adefinite danger near rapidly spinning magnetic tapes. And nowadays few astronomers really look through the telescopes; the important task of detecting light from (faint) objects is more accurately and efficiently done by e/ectronic detectors.Dr. Phillip Grane and electronics engineer Walter Nees at ESO in Geneva are developing such a detectorandexplain how it works and what it can do.
Collaboration on the use of the 4 cm and 9 cm McMullan electronographic cameras at the Danish 1.5 m telescope.
Gyldenkerne, K.; Nielsen, R. F.; McMullan, D.
AA(Copenhagen University) AB(Copenhagen University) AC(Royal Greenwich)
Two electronographic cameras have now been operating at the Oanish 1.5 m telescope on La Silla during several months. They assure an efficient use of this fine telescope and many exciting photos have already been obtained. Ors.K. Gyldenkerne and R. Florentin Nielsen of the Copenhagen University Observatory and Dr. 0. McMullan of the Royal Greenwich Observatory explain how these cameras work and inform about some of the far-reaching observing programmes that have been initiated.
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Discovery of a new eclipsing dwarf nova: OY Carinae.
The weather at the beginning of the night April 29/30, 1979 was not excellent on La Silla: Most clouds were gone, but many of them were just waiting near the horizon and threatened to come back. After twilight I pointed the ESO 1 m telescope to the southern dwarf nova OY Gar, which is a faint variable star of about 16~. The first photoelectric measu rement, however, revealed 14~'8, a bit brighter than normal, and it seemed to brighten up rapidly. Of course, this is not unusual for a dwarf nova: OY Gar just was beginning one of its eruptions. lieft the telescope on the star monitoring it continuously in 3-second time intervals.