Absolute Spectrophotometry of Wolf-Rayet Stars: Are the Colors the Same?

1982 ◽  
Vol 99 ◽  
pp. 121-125
Author(s):  
Philip Massey
Keyword(s):  
Broad Band ◽  
Emission Lines ◽  
Photoelectric Photometry ◽  
Interference Filters ◽  
One Step

Until now, all that we've known about the magnitudes and colors of Wolf-Rayet stars has been based on photoelectric photometry made with 50–150 A wide interference filters, selected to exclude as far as possible the stronger emission lines (Westerlund 1966; Smith 1968, Lundstrom and Stenholm 1979). This was clearly an improvement on the pioneering efforts of Pyper (1966), who obtained broad band photometry and attempted to correct for the presence of emission; nevertheless, with modern detectors it is possible to go one step further.

Photoelectric photometry of eclipsing binary V375 cassiopeiae

1986 ◽  
Vol 10 (4) ◽  
pp. 265-271 ◽  
Author(s):  
Zhang Rong-Xian ◽  
Zhang Ji-tong ◽  
Li Qi-sheng ◽  
Zhai Di-sheng
Keyword(s):  
Photoelectric Photometry ◽  
Eclipsing Binary

scholarly journals Concerning the Temperatures of Central Stars of Planetary Nebulae

1983 ◽  
Vol 103 ◽  
pp. 534-535
Author(s):  
L. Kohoutek ◽  
W. Martin
Keyword(s):  
Effective Temperature ◽  
Planetary Nebulae ◽  
Photoelectric Photometry ◽  
Effective Temperatures ◽  
Central Stars

Recently Pottasch (1981, Astron. Astrophys. 94, L13) published extremely high effective temperatures of some central stars of planetary nebulae (> 200 000 K). Our study of planetary nebulae based on photoelectric photometry does not confirm his results. A histogram of Tz(HI) and Tz(HeII) shows smooth distribution of Tz with the maximum of about 48 000°K (HI) and 90 000°K (HeII), respectively; the effective temperature of none of the 62 planetary nuclei exceeds 120 000°K.

scholarly journals Variations in the color of jupiter

1971 ◽  
Vol 40 ◽  
pp. 349-352
Author(s):  
Neil B. Hopkins ◽  
William M. Irvine
Keyword(s):  
Time Scales ◽  
Opposite Effect ◽  
Central Meridian ◽  
Photoelectric Photometry ◽  
Narrow Bands ◽  
Jovian Atmosphere

Observations of Jupiter by multicolor photoelectric photometry in 10 narrow bands between 3150 Å and 1.06 μ and in UBV showed a brightening for shorter wavelengths in 1965 relative to 1963. An opposite effect occurred for the band at 7300 Å. These results are consistent with observed activity in the Jovian atmosphere. No obvious correlation could be found between brightness fluctuations and longitude of the central meridian, indicating that the activity was uniform in longitude or occurred on time scales short compared to a month.

On the Measurement of Atmospheric Extinction by Rufener’s Method

1979 ◽  
Vol 3 (5) ◽  
pp. 326-327
Author(s):  
Z. KviZ
Keyword(s):  
Adverse Effect ◽  
Photometric System ◽  
Photoelectric Photometry ◽  
Atmospheric Extinction ◽  
Air Mass

The coefficient of atmospheric extinction may change during the night and in fact it often does. This has an adverse effect on the determination of atmospheric extinction by simple Bouguer plot of magnitude against air mass. This effect was studied by Rufener (1964), who introduced for the purpose of accurate photoelectric photometry in the Geneva photometric system the method of two ‘extinction stars’. His method consists of the measurement of two stars of the same colour — one starting at high air mass 2 - 3, the M-star (for French montante = rising) and the second starting simultaneously in the meridian at low air mass, the D—star (for descending).

scholarly journals Evidence for Mass Segregation in NGC 5466

1988 ◽  
Vol 126 ◽  
pp. 677-678
Author(s):  
James M. Nemec ◽  
Hugh C. Harris
Keyword(s):  
Globular Cluster ◽  
Binary Systems ◽  
Low Frequency ◽  
Close Binary ◽  
Photoelectric Photometry ◽  
Significance Level ◽  
Blue Stragglers ◽  
Mass Segregation ◽  
The Masses ◽  
Subgiant Stars

Forty-eight blue straggler stars have been discovered in NGC 5466, the only Galactic globular cluster known to contain an anomalous Cepheid of the sort found in dwarf galaxies. The stars were identified in color-magnitude diagrams constructed from photometry of deep photographic plates taken with the Canada-France-Hawaii 3.6 m telescope (calibrated with new UBV photoelectric photometry), and from point spread function photometry of CCD frames taken with the Palomar 5 m telescope. The stars typically have magnitudes <V> ~ 19.m1 and colors <B-V> ~ 0.m2. Forty-two of the 48 stars are situated inside of R=2.5 arcmin (see Fig.1), the projected radius containing half the cluster luminosity, and only six stars are found between 2.5 and 9 arcmin. A one-sided, two-sample Kolmogorov-Smirnov test (using the CCD data) establishes at the 98% significance level that the blue stragglers are more centrally concentrated than the subgiant stars of the same magnitude. By fitting multi-component King models to the projected radial distributions (Fig.2), the mean mass of the blue stragglers is shown to be ~1.5 to two times larger than the masses of the stars that contributed the light from which the core and tidal radii were derived (i.e. M (Blue Str.)=1.3±0.3 M⊙). Because the central relaxation time for NGC 5466 is much less than the cluster age, the different radial distributions are attributed to mass segregation. A similar mass segregation is also observed in the globular cluster NGC 5053, where Nemec and Cohen (1986, in preparation) have recently identified ~30 blue stragglers. The low stellar density and small escape velocity of NGC 5466 make a recent epoch of star formation (during which the blue stragglers might have formed as massive single stars) seem unlikely. Instead, the blue stragglers probably are either close binary systems that have transferred mass, or are coalesced stars. The very low frequency of stellar collisions expected in the center of NGC 5466 suggests that the blue stragglers are primordial binary systems. The simultaneous presence in NGC 5466 of the blue stragglers and the anomalous Cepheid V19, and their relative numbers, supports the hypothesis that there is an evolutionary connection between the two types of stars. By fitting theoretical isochrones to the photographic c-m diagram, NGC 5466 is estimated to have an age of 18±3 Gyr.

scholarly journals Third General Catalogue of MK Spectral Classifications

1977 ◽  
Vol 35 ◽  
pp. 285-286 ◽  
Author(s):  
William Buscombe
Keyword(s):  
Research Articles ◽  
Photoelectric Photometry ◽  
General Catalogue

For the convenience of astronomers who need information concerning certain stars but prefer not to search through hundreds of research articles in the hope of finding it, a file of MK spectral types and UBV photoelectric photometry is maintained at Dearborn Observatory. A generous donor made possible the publication in 1974 of a listing of approximately 17,000 IBM cards of data compiled by Pamela M. Kennedy and William Buscombe during 1963-1973.

scholarly journals Photometry of the δ Scuti Star DG Leo: Preliminary Results

2004 ◽  
Vol 191 ◽  
pp. 73-74 ◽  
Author(s):  
P. Lampens ◽  
R. Garrido ◽  
L. Parrao ◽  
J.H. Peña ◽  
T. Arentoft ◽  
...  
Keyword(s):  
Orbital Period ◽  
Noise Level ◽  
Amplitude Spectrum ◽  
Slow Variation ◽  
Photoelectric Photometry ◽  
Period Analysis ◽  
Preliminary Results ◽  
Spectroscopic Binary ◽  
Scuti Star ◽  
Triple Star

AbstractNew uvby photoelectric photometry has been acquired for the triple star DG Leo at two different observatories equipped with analogous instrumentation. A preliminary period analysis indicates the presence of at least 3 close δ Scuti frequencies (10-12 c/d, 3-6 mmag) and a slow variation. This slow variation fits quite well with half the orbital period of the spectroscopic binary; the noise level in the amplitude spectrum is only 3–4 mmag (after prewhitening).

Photoelectric photometry of the open cluster Tr-1

1977 ◽  
Vol 48 (1) ◽  
pp. 225-230 ◽  
Author(s):  
U. C. Joshi ◽  
Ram Sagar
Keyword(s):  
Open Cluster ◽  
Photoelectric Photometry
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