AR Lacertae Research Articles

Two-colour photoelectric investigation of AR Lacertae

The RS CVn-type eclipsing binary AR Lac has been observed in two colours,B andV, in 1978 and 1979. Several times of minima have been obtained during the observations and the new light elements have been calculated. The orbital period of the system was found to be decreasing with an amount of 14.6 s century−1. The light curves of the system obtained inB andV show a significant wave-like distortion outside eclipses. The amplitudes of the wave-like distortion inB andV are about 0 . 09 and 0 . 10 in 1978, and, 0 . 12 and 0 . 13 in 1979, respectively. The minima of the wave-like distortion have shifted with an amount of 0 . 40 in one year, thus indicating the migration period of the wave-like distortion is about 2.5 yr. A noticeable variation of light during the totality of primary minimum has also been observed. This variation can be attributed to the distortion wave which has been moving towards decreasing phases.

Calcium H and K emission in AR Lacertae

Calcium H and K emission in AR Lacertae

Observations with the VLA of the radio binary star AR Lacertae

view Abstract Citations (22) References (10) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Observations with the VLA of the radio binary star AR Lacertae. Owen, F. N. ; Spangler, S. R. Abstract Radio observations of AR Lac during three optical eclipses are reported. The observations were made at 4585 MHz with the Very Large Array (VLA) telescope. No clearly defined minimum was found during any of the three eclipses observed. Thus, the radio emission of AR Lac does not originate from a very compact source located at the center of mass of the system. If the radio source is roughly spherical, uniform, and between the two stars, this result suggests that the brightness temperature is no more than about 4 billion K. If the radio source is self-absorbed, as is suggested by the characteristic radio spectrum of AR Lac, then the Lorentz factor of the radiating electrons is less than 4. Publication: The Astrophysical Journal Pub Date: October 1977 DOI: 10.1086/182534 Bibcode: 1977ApJ...217L..41O Keywords: Binary Stars; Radio Stars; Radio Telescopes; Variable Stars; Late Stars; Microwave Emission; Very Large Array (Vla); Astronomy full text sources ADS | data products SIMBAD (1)

On the period variations in AR Lacertae

view Abstract Citations (23) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the period variations in AR Lacertae. Hall, D. S. ; Richardson, T. R. ; Chambliss, C. R. Abstract Examination of 18 light curves, obtained between 1926 and 1974, shows that there is a wave-like distortion outside eclipse which migrates towards decreasing orbital phase at a rate which varies between 10 or 15 yrlcycle and 50 or 60 yrlcycle. The wave amplitude (max to min, in the blue) varies between about 0". 1 and 0".04. Examination of the 0 - C curve between 1900 and 1972 shows that two obvious period decreases (1932 and 1966) and one obvious increase (1957) occurred when the minimum of the wave was at O .2S and O .7 5, respectively. This same correlation has been established or suspected in RS CVn, SS Cam, RT Lac, CG Cyg, and V47 1 Tau. Extrapolation of the migration curve would indicate that AR Lac experienced a second period increase around 1974+3. Publication: The Astronomical Journal Pub Date: December 1976 DOI: 10.1086/111996 Bibcode: 1976AJ.....81.1138H Keywords: Eclipsing Binary Stars; Light Curve; Stellar Spectrophotometry; Variable Stars; H Alpha Line; Orbital Elements; Stellar Motions; Astronomy full text sources ADS | data products SIMBAD (7)

Radio Stars AR Lacertae and Cygnus X-2

We report observations of radio emission from two stars: AR Lacertae, an Algol-type eclipsing and spectroscopic binary with a period of 1.98 d; and the peculiar blue star suggested1 as the optical counterpart of the X-ray source Cygnus X-2. AR Lac is one of about thirty close binaries with known period anomalies2 that were searched for radio emission between February 19 and 28, 1973, with the NRAO interferometer operating at 2,695 and 8,085 MHz; and Cyg X-2 was one of about fifteen X-ray sources being examined for radio emission between March 9 and 15, 1973.

VARIATIONS IN THE LIGHT CURVE OF SV CAMELOPARDALIS

The eclipsing binary SV Camelopardalis was reobserved during the spring of 1962, and the light curve is compared here to that observed by Huffer and Nelson1 in 1951. The 1962 observations were made with the new 24-inch reflector at San Diego State College. This instrument is equipped with a photometer using a refrigerated 1P21 photomultiplier and standard Johnson-Morgan U, B, V filters.2 The photometer, built in the observatory shop by R. J. Roome and G. O. Jones, is of conventional design, and the associated electronic equipment is composed of standard commercially available units. The linearity of the amplifier was tested by using a potentiometer, and the linearity and color response of the entire system was tested by observing a number of stars in M 39. The results compare satisfactorily with those published by Johnson for this cluster.3 Figure 1 shows the light curve of SV Camelopardalis in 1951 with HD 44706 as a comparison star; Figure 2 shows it in 1962 when HD 43883 was used as a comparison star. This binary has an interesting history of variations in its light curve, beginning with the 1946 report by Wood.4 His 1939 photographic observations show a hump of about 0TM2 in the light curve just preceding primary minimum. Huffer and Nelson found the situation reversed;1 that is, in 1951 the maximum following primary minimum was about 0^05 higher than the other maximum. The 1962 curve once again shows the high maximum preceding the primary minimum, but the difference between maxima is in this case about 0TMl. The 1948-49 light curve published by DeWitt and Seyfert5 does not show this effect to any noticeable extent, but the 194950 observations of G. E. Kron and Mrs. Kron6 led them to classify SV Camelopardalis, along with AR Lacertae and RT Andromedae as a binary whose light-curve peculiarities may be interpreted in terms of surface spots. Hiltner's 1947 light curve7

NOTES ON STELLAR SPECTRA

Phi Persei. This star has a well-known helium-shell spectrum, with He i 3965 sharp, while those lines which have nonmetastable lower levels are usually broad and shallow. The H lines show absorption cores between broad emission wings. Several spectrograms, obtained on October 22, 1951, with the coude spectrograph of the Mount Wilson 100-inch telescope show that He i 3888 and He i 3188 (23S n3P°) also have strong absorption cores. But while the //-cores are distinctly unsymmetrical, or even double, being shaded shortward, the He cores are nearly symmetrical. Especially interesting is an exceedingly narrow, deep, absorption line which is centrally superposed over the normal absorption core of He i 3888. This feature has not been seen previously since it requires a dispersion of at least 10 A/mm. Its width is so small that it must come from an even higher layer than the rest of the He and H shell spectrum. Rotation, which at the normal shell level is sufficient to appreciably broaden the cores of many lines, is negligible at the height where the very narrow line originates. Moreover, turbulence at this high level is also negligible : it must be less than 2 or 3 km/sec, resembling in this respect the conditions within interstellar gas clouds. Since there is strong independent evidence that at more moderate heights, within extended stellar atmospheres, the turbulence at first increases with the height, we must now conclude that at still higher elevations it decreases. The H absorption cores are not very strong and can be seen as distinct, narrow lines only to H 14. Beyond this limit there are a few diffuse absorption features which probably result from the overlapping of broad underlying hydrogen lines. Even these disappear long before the Balmer limit is reached. AR Lacertae. The discovery of double absorption lines in the s Canis Ma joris stars, 12 Lacertae and o Scorpii, has led to

The Spectra and Orbits of AR Lacertae.

The Spectra and Orbits of AR Lacertae.

An Attempt to Detect Polarization in the Cα II Emission Lines of AR Lacertae.

An Attempt to Detect Polarization in the Cα II Emission Lines of AR Lacertae.

An infrared light-curve for the Woif-Rayet eclipsing variable HD 193576.

Observations of HD 193576 in the region of 7200 A were made in 1943 and 1946 with a photoelectric photometer. Either the eclipsing binary or the comparison star, HD 193514, is intrinsically variable from night to night with an extreme range of 0. I mag. A night-to-night analysis of observations made at 4500 A' also shows a variation with an extreme range of o.o6 mag. No check has as yet been made on the constancy of the comparison star, but the determination of intrinsic variation in another bright-line eclipsing variable, AR Lacertae, points to intrinsic variation in the binary. Observations of two eclipsing binaries without bright lines, ot CrB and YZ Cass, which do not show intrinsic variability also lend support to the assumption of variation in HD 193576 rather than its comparison star. Observations of primary minimum, both in the infrared and the blue, in 1946 show it to be occurring 0d02 later than in 1940 and 1942, whereas the 1943 observations indicate the midpoint was occurrff~g 0d01 earlier. A mean light- curve in the infrared has been obtained after complete corrections for phase shift and night- to-night light variations in primary minimum. The depth of primary minimum is 0.26 mag. and that of secondary minimum, 0.19 mag. These values refer to depth from the respective shoulders; the shoulders of secondary minimum seem to be about 0.02 mag. brighter than those of primary minimum. A comparison of the infrared and the blue curves for primary minimum, after the former is corrected to the same depth as the latter, reveals no significant difference in form or width. I.A~. J. ~7, 311, 1943. Lick Observatory, Mt. Ma milton, Ca 1sf.

AR Lacertae, variabile a eclisse

Astronomische NachrichtenVolume 237, Issue 14 p. 249-252 Miscellaneous AR Lacertae, variabile a eclisse Luigi Jacchia, Luigi Jacchia BolognaSearch for more papers by this author Luigi Jacchia, Luigi Jacchia BolognaSearch for more papers by this author First published: 1929 https://doi.org/10.1002/asna.19292371403Citations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume237, Issue141929Pages 249-252 RelatedInformation