SCIENCE IN THE LIBERAL ARTS CURRICULUM - A PERSONAL VIEWYoung, A.
doi: 10.1086/131273pmid: N/A
A discussion concerning the character and importance of the epistemological structure of science notes that contemporary textbooks and traditional courses used in the scientific component of the liberal arts curriculum do not communicate that structure. A course, designated 'The Structure of Scientific Thought', is suggested as a vehicle for communicating to nonscientists the fundamental aspects of scientific inquiry, and the shortcommings of traditional textbooks and courses are illustrated by contrast to its contents. Attention is given to such aspects of the structure of science as empiricism, conceptualization, the relationships among science, truth and reality, theoretical hierarchies, the distinction between explanation and understanding, and the centrality of abstraction and mathematical formalism in science.
MAIN-SEQUENCE PHOTOMETRY FOR THREE GALACTIC GLOBULAR CLUSTERS.Harris, W. E.; Hesser, J. E.; Atwood, B.
doi: 10.1086/131274pmid: N/A
With the SIT Vidicon camera operated in direct mode at the CTIO 4-m telescope, V,(B-V) color-magnitude data have been obtained for the globular clusters 47 Tuc (NGC 104,C0021-723), NGC 288(C0050-268), and NGC 1904(C0522-245). These data in general cover the V magnitude range from 16 to 22, and accurately define the main sequence turnoff positions for all three clusters. By comparison of our data with the recent theoretical isochrones of VandenBerg (1983), it is found that the main sequence loci of the three clusters can be succesfully matched by ages in the range of 16 + or - 3 billion years, if heavy-element abundances which are similar to spectroscopically derived estimates are adopted.
SIT VIDICON PHOTOMETRY FOR FOUR OLD MAGELLANIC CLOUD CLUSTERS.Harris, W. E.; Hesser, J. E.; Atwood, B.
doi: 10.1086/131275pmid: N/A
SIT Vidicon photometry in B and V from the CTIO 4-m telescope is presented for NGC 1466, NGC 2203, NGC 2210, and NGC 2257 in the Large Magellanic Cloud. The deepest data are for NGC 2257, where the main sequence turnoff is reached at V = 22.4, confirming Stryker's (1983) inference from photographic data that the cluster has an age comparable to those of the Galactic globular clusters. NGC 2203 is found to be an intermediate-age cluster with a C-M diagram similar to that of NGC 7789 in the Galaxy. For NGC 1466 and NGC 2210 the present data are compatible with previous studies that have found these to be genuinely old clusters in the Galactic globular cluster sense.
THE FINITE WIDTH OF THE OMEGA CENTAURI MAIN SEQUENCE.Rodgers, A. W.; Harding, P.
doi: 10.1086/131276pmid: N/A
The present photon counting area photometry of Omega Centauri's faint subgiant solor-luminosity array, turnoff, and main sequence are of sufficient precision to indicate an intrinsic width to the main sequence in (B-V) which can be ascribed to chemical inhomogeneity among the stars. The error estimation procedures are detailed, and these data are used to complement a distance modulus determination of the cluster, together with an enhancement of the He abundance between the main sequence and horizontal branching envelopes.
A NOTE ON THE OXYGEN GRADIENT IN NGC 628.Talent, D. L.
doi: 10.1086/131277pmid: N/A
The Kitt Peak 2.1-m telescope and Intensified Image Dissector Scanner have been used to gather spectrophotometric data in the 3600-5200 A spectral region for five H II regions in the spiral galaxy NGC 628. The Pagel et al (1979) technique was then applied to determine the relative number abundances of O to H in each of the H II regions. An examination of the abundance values obtained as a function of the radial coordinate yields an O gradient of -0.05 + or - 0.03 dex/kpc.
ACTIVE BE STARS.Barker, P. K.
doi: 10.1086/131280pmid: N/A
Intensifier director scanner H-alpha profiles are presented of the bright northern Be stars, which have recently developed significant emission line variability. These stars are candidates for intensive spectroscopic, photometric, and polarimetric observations during the current season.
THE DOUBLE-LINED SPECTROSCOPIC BINARY IOTA PEGASI.Fekel, F. C.; Tomkin, J.
doi: 10.1086/131281pmid: N/A
Low-noise Reticon observations of ι Peg at 6430 Å reveal weak, well-defined lines of the secondary. The authors have determined the secondary velocity curve for the first time and have redetermined the primary velocity curve. The orbit is circular with KA = 48.1±0.2 km s-1 and KB = 77.9±0.3 km s-1 and corresponding minimum masses of 1.31±0.02 Msun; and 0.81±0.01 Msun; for components A and B, respectively. The spectral type of the secondary is estimated to be G8 V. The 6707 Å Li I line is measured in both the primary and secondary. The line is unusually strong in the secondary indicating that the system is very young.
DIFFERENTIAL PHOTOMETRY AND ABSOLUTE SPECTROPHOTOMETRY OF CH CYGNI.Kaler, J. B.; Hickey, J. P.; Kenyon, S. J.
doi: 10.1086/131282pmid: N/A
The symbiotic variable CH Cyg has been observed with four-color, H-beta, and other narrow band photometry during a brightening phase between June and November 1981, plus one night each in 1982 and 1983. Both differential photometry and the absolute energy distributions derived from the filters are presented, and an absolutely calibrated Reticon spectrogram taken near maximum brightness in 1982 provides continuum and integrated line fluxes. The data are consistent, with a binary-star hypothesis in which the variation is caused largely by the activity of the hot component. As the star brightened by 0.76 mag at y between June 11 and November 6, 1981, it became somewhat bluer, with a decrease in the (b-y) color index of 0.30 mag. Color changes shortward of b were much smaller. The small flickering variations discovered earlier are readily apparent. The H-beta emission-line fluxes extracted from the wide and narrow-band H-beta filters, as well as from the Reticon spectrum, correlate linearly with the fluxes at u, clearly demonstrating that the emitting mechanism for the line is controlled by the hot component alone. The data from 1982 are closely consistent with those from 1981.