The Mean Light Curve of a Cepheid (L)

BE UMa is a close binary star, not transferring mass, with an extremely hot primary star irradiating the inner face of the cool secondary star. The light curve shows a large-amplitude, sinusoidal variation with a period of 2.29 d, and an eclipse that is centered on the minimum of the variation [1], [3]. According to [1], the eclipse is partial, not total. However, it has been argued [2] that the eclipse was really flat bottomed and thus total. This has important repercussions for the deduced model of the system. To resolve this issue we obtained simultaneous UBVR photometry of BE UMa using the Stiening 4-channel, high-speed photometer on the 82-inch telescope at McDonald Observatory. The mean light curves are shown in Fig. 1. The eclipse in all colours is round bottomed and partial. The different depths are caused by the different contribution from the red secondary star in each bandpass.

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IUE Spectra of The by Dra/Flare Star AU Mic

International Astronomical Union Colloquium ◽

10.1017/s0252921100096172 ◽

1983 ◽

Vol 71 ◽

pp. 249-250

Author(s):

C.J. Butler ◽

A.D. Andrews ◽

J.G. Doyle ◽

P.B. Byrne ◽

J.L. Linsky ◽

...

Keyword(s):

Light Curve ◽

Emission Line ◽

Flare Star ◽

Emission Lines ◽

Spectral Variation ◽

Strong Emission ◽

Line Intensities ◽

The Mean ◽

Phase Interval

A coordinated series of ground-based optical and IUE observations of BY Dra variables was undertaken to follow the spectral variation of these stars over one cycle. In the first series 20 LWR and 19 SWP trailed spectra were taken of AU Mic over a three day period 4-6 August 1980 .In Figure 1 we show the mean integrated fluxes for the strong emission lines in the SWP spectra of AU Mic over the observed phase interval of 0.14 to 0.8 together with an approximate V light curve determined by the FES on IUE. From comparison of the emission line intensities and FES magnitudes in Figure 1 several points emerge.

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New near-infrared JHKs light-curve templates for RR Lyrae variables

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834893 ◽

2019 ◽

Vol 625 ◽

pp. A1 ◽

Cited By ~ 3

Author(s):

V. F. Braga ◽

P. B. Stetson ◽

G. Bono ◽

M. Dall’Ora ◽

I. Ferraro ◽

...

Keyword(s):

Light Curve ◽

Near Infrared ◽

Large Magellanic Cloud ◽

Light Curves ◽

Anchor Point ◽

Phase Point ◽

Pulsation Period ◽

Rr Lyrae ◽

The Mean ◽

The Difference

We provide homogeneous optical (UBVRI) and near-infrared (NIR, JHK) time series photometry for 254 cluster (ω Cen, M 4) and field RR Lyrae (RRL) variables. We ended up with more than 551 000 measurements, of which only 9% are literature data. For 94 fundamental (RRab) and 51 first overtones (RRc) we provide a complete optical/NIR characterization (mean magnitudes, luminosity amplitudes, epoch of the anchor point). The NIR light curves of these variables were adopted to provide new light-curve templates for both RRc and RRab variables. The templates for the J and the H bands are newly introduced, together with the use of the pulsation period to discriminate among the different RRab templates. To overcome subtle uncertainties in the fit of secondary features of the light curves we provide two independent sets of analytical functions (Fourier and periodic Gaussian series). The new templates were validated by using 26 ω Cen and Bulge RRLs. We find that the difference between the measured mean magnitude along the light curve and the mean magnitude estimated by using the template on a single randomly extracted phase point is better than 0.01 mag (σ = 0.04 mag). We also validated the template on variables for which at least three phase points were available, but without information on the phase of the anchor point. We find that the accuracy of the mean magnitudes is also ∼0.01 mag (σ = 0.04 mag). The new templates were applied to the Large Magellanic Cloud (LMC) globular cluster Reticulum and by using literature data and predicted PLZ relations we find true distance moduli μ = 18.47 ± 0.10 (rand.) ± 0.03 (syst.) mag (J) and 18.49 ± 0.09 ± 0.05 mag (K). We also used literature optical and mid-infrared data and we found a mean μ of 18.47 ± 0.02 ± 0.06 mag, suggesting that Reticulum is ∼1 kpc closer than the LMC.

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The Remarkable Eclipsing Binary TW Draconis

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307006539 ◽

2006 ◽

Vol 2 (S240) ◽

pp. 567-570

Author(s):

M. Zejda ◽

Z. Mikulášek ◽

M. Wolf ◽

P. Svoboda

Keyword(s):

Principal Component Analysis ◽

Light Curve ◽

Robust Regression ◽

Principal Component ◽

Velocity Curve ◽

Radial Velocity Curve ◽

Eclipsing Binary ◽

The Mean ◽

Photoelectric Measurements ◽

Short Time

AbstractWe analyzed a new photometry of this well-known Algol-like eclipsing binary together with old photoelectric measurements with the aim of better understanding of its orbital period changes and short-time light variations modulating the mean light curve. The analysis has been done by the new method based on the combination of the principal component analysis and robust regression. New spectroscopic observations and radial-velocity curve are also presented.

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IRAS LRS Spectral Class and Light Curve of M & S Miras

International Astronomical Union Colloquium ◽

10.1017/s0252921100063119 ◽

1989 ◽

Vol 106 ◽

pp. 292-292

Author(s):

M.S. Vardya

Keyword(s):

Light Curve ◽

Mean Amplitude ◽

Asymmetry Factor ◽

Necessary Condition ◽

Infrared Excess ◽

Strong Emission ◽

Spectral Class ◽

Increase With Increase ◽

The Mean ◽

Visual Light

A large sample of 177 Miras, comprising 164 M and 13 S stars, has been examined to determine the dependence of 9.7 μm silicate emission, as revealed by their IRAS LRS Spectral class, on the visual light curve asymmetry factor, f. It is found that the silicate feature occurs not only in M (Vardya et al. 1986; Onaká & de Jong 1987) but in S Miras also only for f ≤ 0.45. This, however, is only a necessary condition, as about one fifth of Miras with f ≤ 0.45 do not show the 9.7 μm emission. This non-detection shows dependence on other parameters like the mean visual light amplitude. Non-detection is highest in the region 0.43 < f ≤ 0.45, as well as when mean amplitude is ≤ 5m.0. Though strong emission features in M Miras may occur for any value of f, very weak features are absent for small values of f, and the strongest feature tends to appear for large values of f. Infrared excess tends to increase with increase in the strength of the silicate emission and with decrease in the value of f.

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The Mean Light Curve of a Cepheid (L)

Exercises in Astronomy ◽

10.1007/978-94-009-3769-7_54 ◽

1987 ◽

pp. 227-229

Author(s):

J. Kleczek

Keyword(s):

Light Curve ◽

The Mean

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Photometric results of the long-term monitoring of the active asteroid (596) Scheila

10.5194/epsc2020-1034 ◽

2020 ◽

Author(s):

Zhong-Yi Lin ◽

Chen-Yen Hsu

Keyword(s):

Light Curve ◽

Rotation Period ◽

Impact Event ◽

Mean Values ◽

Photometric Observations ◽

The Mean ◽

The Difference ◽

The Impact ◽

Term Monitoring

(596) Scheila was observed to have an active appearance as a result of impact event in late 2010. In additional the coma feature, the shape of light curve had been found the difference probably fresh material or surface properties changed around the impact site. In this study, we present the results of our monitoring observations obtained in 2014 and 2019-2020. The mean values of the color indices (B&#8722;V&#160;= (0.75 &#177; 0.08)m,&#160;V&#8722;R&#160;= (0.45 &#177; 0.04)m, and&#160;R&#8722;I&#160;= (0.44 &#177; 0.09)m) agree well with the values for asteroids of the D-types. The rotation period of the asteroid estimated from photometric observations in 2014 is 15.8 &#177; 0.1 h.&#160;The shape of the light curve is similar as that found after impact event. Furthermore, we did not find any rotational color variability in B-V, V-R and R-I diagrams, meaning the observed surface in this observing period of 2019-2020 is homogeneous.

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Analytic solutions to the maximum and average exoplanet transit depth for common stellar limb darkening laws

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834620 ◽

2019 ◽

Vol 623 ◽

pp. A137 ◽

Cited By ~ 7

Author(s):

René Heller

Keyword(s):

Light Curve ◽

Impact Parameter ◽

Extrasolar Planets ◽

Analytic Solutions ◽

Radius Ratio ◽

Average Intensity ◽

The Mean ◽

Impact Parameters ◽

In Transit ◽

Limb Darkening

Context. The depth of an exoplanetary transit in the light curve of a distant star is commonly approximated as the squared planet-to-star radius ratio, (Rp/Rs)2. Stellar limb darkening, however, can result in significantly deeper transits. An analytic solution would be worthwhile to illustrate the principles of the problem and predict the actual transit signal required for the planning of transit observations with certain signal-to-noise requirements without the need of computer-based transit simulations. Aims. We calculate the overshoot of the mid-transit depth caused by stellar limb darkening compared to the (Rp/Rs)2 estimate for arbitrary transit impact parameters. In turn, this allows us to compute the true planet-to-star radius ratio from the transit depth for a given parameterization of a limb darkening law and for a known transit impact parameter. Methods. We compute the maximum emerging specific stellar intensity covered by the planet in transit and derive analytic solutions for the transit depth overshoot. Solutions are presented for the linear, quadratic, square-root, logarithmic, and nonlinear stellar limb darkening with arbitrary transit impact parameters. We also derive formulae to calculate the average intensity along the transit chord, which allows us to estimate the actual transit depth (and therefore Rp∕Rs) from the mean in-transit flux. Results. The transit depth overshoot of exoplanets compared to the (Rp/Rs)2 estimate increases from about 15% for main-sequence stars of spectral type A to roughly 20% for sun-like stars and some 30% for K and M stars. The error in our analytical solutions for Rp∕Rs from the small planet approximation is orders of magnitude smaller than the uncertainties arising from typical noise in real light curves and from the uncertain limb darkening. Conclusions. Our equations can be used to predict with high accuracy the expected transit depth of extrasolar planets. The actual planet radius can be calculated from the measured transit depth or from the mean in-transit flux if the stellar limb darkening can be properly parameterized and if the transit impact parameter is known. Light curve fitting is not required.

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Changes in the Period of the Eclipsing System AH Virginis

Publications of the Astronomical Society of Australia ◽

10.1017/s1323358000021305 ◽

1982 ◽

Vol 4 (4) ◽

pp. 411-413

Author(s):

H.D. Kennedy

Keyword(s):

Light Curve ◽

Secondary Minimum ◽

Constant Light ◽

Primary Minimum ◽

Minimum Light ◽

The Mean ◽

Photoelectric Observations ◽

Orbital Solution

Guthnick and Prager (1929) were the discoverers of the variability of AH Virginis. Prager (1929) produced a photographic light curve the same year. Lause (1934, 1935, 1937) observed the system visually and improved the period as deduced by Prager. Further visual work on the system was done by Zessewitsch (1944). The first photoelectric observations came from Huruhata and Nakamura (1951), followed in 1952 by Kitamura, Tanabe and Nakamura (1957).Lack of their data on ingress and egress at primary eclipse resulted in the mean curve showing a rounded bottom during minimum light. From this, an inclination of the system of 61° was derived by Kopal and Shapley (1956). Two years later, Kwee (1958) revealed primary minimum to be flat bottomed; the light remaining constant for some 40 minutes. This was confirmed by Binnendijk (1960), thus classifying AH Virginis as one of the few W UMa systems which display complete eclipses at an inclination likely to be closer to 90° then to 61°. Observations of the present study confirm constancy of light of 40 minutes duration during primary minimum. Assuming i = 90°, a new orbital solution was derived by Kitamura and Takahashi (1959) showing constant light for both minima. Binnendijk’s observation, however, showed a curved appearance at secondary minimum. The present observations indicate curved as well as flat secondary minima.

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The Peculiar Slow Nova X Serpentis

International Astronomical Union Colloquium ◽

10.1017/s0252921100068536 ◽

1990 ◽

Vol 122 ◽

pp. 165-166

Author(s):

H.W. Duerbeck ◽

W.C. Seitter

Keyword(s):

Light Curve ◽

Galactic Plane ◽

Absolute Magnitude ◽

Photometric Data ◽

Published Data ◽

Harvard College ◽

Regular Variable ◽

The Mean ◽

Harvard College Observatory ◽

Plate Collection

The very slow nova X Ser (t3 = 555d), situated at a large distance from the galactic plane (z ≈ 4kpc), reached maximum light at 9m in May 1903. It was discovered 5 years later on a Harvard plate (Leavitt 1908). No outburst spectrum is known. A photographic outburst light curve is given by Walker (1923); additional photometric data were published by Sakharov (1954) and Kinman et al. (1965). The light curve, shown in Fig. 1, presents 10-day means, based on all published data, and unpublished data taken from Emily Hughes Boyce’s notebook, Harvard College Observatory Plate Collection.Hughes Boyce (1942) discovered a 275d periodicity during minimum light. From the fragmentary light curve in Fig. 1, including three more recent ‘oscillation’ maxima, a period of 277 days is found. If one assumes that the nova reached Mpg = −6 at maximum, the typical value for a slow nova, the mean absolute magnitude at minimum, Mpg = +2, together with the observed amplitude of about 2m and a relatively long mean period, suggests a very late-type (typically M6e) semi-regular variable.

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