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Produced by the NASA Center for Aerospace Information (CASI) n 0 nt: NASA NGR 05-007-489 j 1 i 3 1 i 1 Investigation of the Shell Stars o And and 0 Per, and of the Eclipsing Binary S Lyr {{i 31 j i Final Technical Report for the period May 1, 1974 through December 31, 1975 1 i a-? 3' 5^^,` Principal Investigator: Miroslav PlavMAR 1976 Department of Astronomy (',,^'!^NASA SCI FACILIR University of California INPUT BRANCF: Los Angeles, CA 90024 (NASA-CF-146432) INVESTIGATION THE SHELL N76-20039 STARS OMICRON AND AND THETA PER, AND CF THE ECLIPSING BINARY BETA LYR Final Technical Report, 1 May 1974 - 31 Dec. 1975 Unclas (California Univ.) 19 p HC $3.50 CSCL 03A G3,f89 20633 -I- I. Introduction This Final Report summarizes the status of the work on the project at the time of the expiration of the grant, i.e. December 31, 1975• The grant covered the period May 1, 1974 through December 31, 1975 (including the extension period without additional funds, May 1, 1975 through December 31, 1975). The original idea of the project was based on the assumption that in all three stars to be investigated, there is a reasonable chance to detect lines of the secondary component in the far UV. The chance was particularly strong in 5 Lyrae where recent work has shown rather co,.vincingly that the invisible component is the more massive star the system; therefore it was reasonable to look for a hot compact object with detectable lines in the far UV. 0 Persei is almost certainly a binary star, as shown most convincingly by Hynek, who suggested that both components are B stars. Hynek's model has recently been developed by Hendry (1975), who made a case for a B3V secondary. This, too, gave reasonable hopes for detecting the secondary lines in the Copernicus spectra. The duplicity of o Andromedae remains highly cohtroversial. One can argue for it from the general hypothesis tnat many Be stars and shell stars are generated by mass transfer in binary systems (Plavec, 1975 anc_ references therein; O A and Harmanec, 1975; Polidan and Peters, 1975; Plavec, Polidan, and Peters, 1973). Or one can accept the rather controversial photometric observations by Schm dt (1959) who suggested that the star is an eclipsing binary, with coi.._+onents approximately B6.5 V and B 7.5 V, but the combined spectrum is often veiled by a common outer envelope, in which the shell lines arise. The hope to detest and identify the secondary components dictated the strategy even in the proposed budget. A considerable part of the grant was to be used on ccmputer, running the evolutionary codes for binary star evolution, as well as programs computing the mass streams between the components. However, no secondary lines were detected in any of the three components. Instead, all three stars showed rather complicated spectra, which require a very detailed spectroscopic analysis. The far UV spectrum of 0 Lyrae is clearly peculiar, with a multitude of emission lines not observed in any other star so far scanned with Copernicus. This made chis star at once the most interesting and also, in a sense, easier to study. The other two stars display a spectrum rich in absorption lines, some of them being fairly broad (as expected for photospheric lines of rapidly rotating objects), some sharp. The latter, clearly non-photospheric lines, posed a special problem, since at the beginning of the project it was not clear which line is interstellar and which is circumstellar. In other words, the degree of peculiarity of the spectra of d Persei and o Andromedae could not be established until surveys of normal stars and of interstellar lirn.^s were available. L {4' 1 l t -2- The work on S Lyrae will be reviewed rather briefly in this Final Report. Two papers have already been published in which the working team presents the results of observations with Copernicus, their discussion and interpretation. These papers are listed at the end of this Report. I believe that the work on 6 Lyrae has been among the best results so far obtained with Copernicus, and that it has also contributed significantly to the current broad discussion on the presence of black holes in binary systems. My work on S Lyrae was terminated in November, 1974, and since then I have concentrated on 0 Persei and o Andromedae. Already the work on $ Lyrae signaled that the initially planned approach, envisaging a rather heavy use of sophisticated computer codes, must be revised. The first steps in the evaluation of the raw observational data: measurement of the spectral lines, isolation of weak lines from noise, identification of lines in available (but incomplete) multiple' tables, measurements of equivalent widths, radial velocit; , restoration of selected line profiles, etc., requires much less extensive computer usage and much more of detailed and careful "manual" work. As a consequence, in order to make further progress on the project, considerable savings had to be made in the budget on computer funds and other items (travel, publication costs), and more money was needed for the ass-stance of a graduate student. The phase of basic reduction of the acquired data is now essentially concluded. The reports on 0 Persei (section III of the present report) and on o Andromedae (section IV) are preliminary, since it will take me several more months to complete publishable articles. Until now, we have generated extensive lists of (1) lines of probably present elements and ions with laboratory wavelengths, taken from the multiplet lists by Moore and by Kelly and Palumbo (632 lines); (Z) interstellar atomic and molecular lines from the list by Morton (1975) and the Princeton list of molecular hydrogen lines (a total of 533 lines); (3) lines observed and identified in the spectrum of +1 C Ma by Underhill (1974) (460 lines); (4) lines found in the course of this project in the UV spectrum scans of 0 Per, o And, a Gru, a Sco and 3-4 other comparison spectra (896 lines listed until now; the work has not yet been completed). Ba,ei on the intercomparison of these lists, a complete list of line identifi- cations is being prepared (and is well advanced) separately for the hot star 0 Persei (spectral type about B0.5 IV) and for the ccoler o Andromedae (about B6 V). A considerable effort was made to find and identify circum- stellar lines in the spectra of both stars. Such identification.q could not be considered reliable before the availability of Morton's list of interstellar lines; in certain cases, ambiguity remains even now. A very aEcisive step forward was the re-observation of o And in August 1975. It revealed substantial changes in many of the sharp and moderately sharp lines, thereby identify7ng them as circumstellar. For ¢ Persei, two runs were made already in 1973, but because of 5 some misunderstandings, separate corrected sets of data were not -3- available to me until February 1976. Duplicate observations of 0 Per at two different orbital phases are less helpful for segregating circumstellar and interstellar lines, however, since the circumstellar shell lines in this star seem to vary very little with phase. Also, an important part of the auxiliary work on data reduction has been the meaourement of equivalent widths of a large number of lines. The research assistant has also worked under my guidance on comprehensive computer codes which enable us to calculate absorption and emission line profiles produced by extended atmospheres, using the principles developed by Marlborough and by Sobolev. This part of the work is also being pr-pared for publication in the near future. The underlying geometrical models of extended atmospheres differ from the f-pe of envelopes considered by either Marlborough or Sobolev, and are `.,he direct outcomes of my theoretical work on mass transfer in binary stars (see, for example, Plavec, 1973, or Plavec, Ulrich and Polidan, 1974). When the basic reduction of the data on 6 Per and o And is finished, an attempt will be made to study these stars in the light of the above-mentioned theoretical models of circumstellar disks generated by mass transfer. Thus, in this respect the work reported here is related to my studies of mass transfer and duplicity of Be stars and shell stars, as presented also at the I.A.U. S: posium No. 71 on Be Stara and Shell Stars at Bass River, in September 1975 (to be published by Reidel, edited by A. Slettebak). The two Preliminary Reports that follow have been made available to, and used by, T. P. Snow in his review paper "A Review of Ultraviolet Astronomical Research with the Copernicus satellite," 1976 (submitted to Earth and Extraterrestrial Sciences). -4- II, Final Report on 0 Lyrae In order to study 0 Lyrae, I organized an ad hoc working group of several outstanding investigators interested in the project: Dr.