BVRcIc light curve of eclisping binary V1023 Persei
Short Name:
J/AJ/160/175
Date:
09 Dec 2021
Publisher:
CDS
Description:
V1023 Per is a polar spotted, but well-detached dwarf binary, very likely a Pre-WUMa eclipsing binary. It was observed on 11 nights in 2015 October, November, and December at Dark Sky Observatory in North Carolina with the 0.81m reflector of Appalachian State University. The period behavior is complex and may be increasing with a cubic or quadratic ephemeris. Its odd light curves are of high amplitude but have no totality and reach maximum light just before and following the secondary eclipse, indicating that it has polar spots similar to UV Leo. The 28yr orbital period study calls the attention of observers to further monitor this binary to understand the complex nature of the period evolution. Its presently fixed polar spot does indicate that it must have a strong magnetic field and that it is synchronously rotating. The BVRcIc simultaneous 2016 Wilson-Devinney program (W-D) solution gives fillouts of 68% and 75% for the primary and secondary components, respectively. The polar position of the spot, its radius (24{deg}), and T-fact (0.75) indicate that a strong magnetic field is present. The small {Delta}T in the components (~289K) show that the stars are similar in spectral type despite them being well detached. The inclination is high, ~85.19{deg}{+/-}0.04{deg}, but there is not a total eclipse due to the high mass ratio (~0.739{+/-}0.001). Due to the low galactic position (longitude=150.390{deg}, latitude=-1.023{deg}), its reddening is addressed. The primary components temperature is estimated to be 5250{+/-}250K.
LU Lac is a neglected W UMa binary star in photometric investigations. In this paper, we present BVRI CCD photometric light curves obtained on one night in 2012. The first photometric solutions of this system are computed by using the Wilson-Devinney code. It is shown that LU Lac is a marginal contact W-type system with a degree of contact factor of f=8.9%, a mass ratio of q=2.085 and a high inclination of i=82.20{deg}. From the first analyses of orbital period changes, we found the period variation of the system includes an oscillation (A3=0.0125-days and T3=51.92-years). The cyclic change may be attributed to the light-travel time effect through the presence of a third body.
We report the BVR_c_I_c_ data for 10 blazars observed in the first phase of a long-term photometric monitoring program of about 30 objects. The observations were carried out with a 0.40-m automatic imaging telescope, recently developed by our group at the Perugia University Observatory. During our period of observation 1215+303 and 1424+240 were at their highest values of magnitude, while 0754+100 and 0829+043 displayed large amplitude flares. We further report optical data of Mrk 501 during the same period in which TeV {gamma}-rays were detected by the Whipple Observatory. For a description of the (RI)c photometric system, see e.g. the General Catalog of Photometry Data <GCPD/54>.
We performed a photometric study of globular clusters around the isolated elliptical galaxy NGC 821. B, V and R-band photometry come from the Mini-Mosaic imager on the 3.5-m Wisconsin Indiana Yale NOAO (WIYN) telescope. Observations were conducted between November 30 - December 2, 2005. Average seeing conditions were ~0.7". Two Hubble Space Telescope (HST) Wide-Field Planetary Camera 2 (WFPC2) fields were analysed in the V and I-bands. Objects in this catalogue are the globular cluster candidates according to the selection criteria detailed in the journal article. Astrometric solution is from USNO-B stars. Note the center of NGC 821 on this system is located at 02:08:21.118 +10:59:42.21. Photometry has been corrected for Galactic extinction and we used a distance modulus of m-M=31.75 in our analysis.
The moderately fast Nova Oph 2007 reached maximum brightness on 2007 March 28 at V=8.52, B-V=+1.12, V-Rc=+0.76, V-Ic=+1.59 and Rc-Ic=+0.83 , after fast initial rise and a pre-maximum halt lasting a week. Decline times were t^V^_2_=26.5, t^B^_2_=30, t^V^_3_=48.5 and t^B^_3_=56.5d. The distance to the nova is d=3.7+/-0.2kpc , the height above the Galactic plane is z=215pc, the reddening is E(B-V)=0.90 and the absolute magnitude at maximum is M^max^_V_=-7.2 and M^max^_B_=-7.0. The spectrum four days before maximum resembled a F6 supergiant, in an agreement with broad-band colours. It later developed into that of a standard 'FeII'-class nova. Nine days past maximum, the expansion velocity estiIIted from the width of H{alpha} emission component was ~730km/s, and the displacement from it of the principal and diffuse-enhanced absorption systems was ~650 and 1380km/s, respectively. Dust probably formed and disappeared during the period from 82 to 100d past maximum, causing (at peak dust concentration) an extinction of {Delta}B=1.8mag and an extra {Delta}E(B-V)=0.44 reddening.
High-precision, space-based photometric missions like CoRoT and Kepler have revealed new and surprising phenomena in classical variable stars. Such discoveries were the period doubling in RR Lyrae stars and the frequent occurrence of additional periodicities some of which can be explained by radial overtone modes, but others are discordant with the radial eigenfrequency spectrum. We search for signs of period doubling in CoRoT RR Lyrae stars. The occurrence of this dynamical effect in modulated RR Lyrae stars might help us to gain more information about the mysterious Blazhko effect. The temporal variability of the additional frequencies in representatives of all subtypes of RR Lyrae stars is also investigated.
We present B, V, R, and H{alpha} photometry of eight clusters in the Small Magellanic Cloud, five in the Large Magellanic Cloud, and three Galactic clusters and use two-color diagrams (2-CDs) to identify candidate Be star populations in these clusters. We find evidence that the Be phenomenon is enhanced in low-metallicity environments, based on the observed fractional early-type candidate Be star content of clusters of age 10-25Myr.
We present B,V,R,Halpha CCD photometry and astrometry of Be stars in NGC 1818, its small neighbouring cluster NGC 1818B, and the surrounding field down to V = 18 mag. Our Be star identifiers conform to IAU specifications. For a description of the UBVRI and Halpha systems, see e.g. <GCPD/08> and <GCPD/55>
BVRI and spectroscopic light curves of S5 0716+714
Short Name:
J/ApJ/888/30
Date:
21 Oct 2021
Publisher:
CDS
Description:
In order to study short timescale optical variability of {gamma}-ray blazar S5 0716+714, quasi-simultaneous spectroscopic and multiband photometric observations were performed from 2018 November to 2019 March with the 2.4m optical telescope located at Lijiang Observatory of Yunnan Observatories. The observed spectra are well fitted with a power law F_{lambda}_=A{lambda}^-{alpha}^ (spectral index {alpha}>0). Correlations found between {dot}{alpha}, {dot}A, {dot}A/A, {dot}F_{lambda}_, and {dot}F_{lambda}_/F_{lambda}_ are consistent with the trend of bluer-when-brighter (BWB). It is the same case for colors, magnitudes, color variation rates, and magnitude variation rates of photometric observations. The variations of {alpha} lead those of F_{lambda}_. Also, the color variations lead magnitude variations. The observational data are mostly distributed in the I(+,+) and III(-,-) quadrants of the coordinate system. Both spectroscopic and photometric observations show BWB behaviors in S5 0716+714. The observed BWB may be explained by the shock-jet model, and its appearance may depend on the relative position of the observational frequency ranges with respect to the synchrotron peak frequencies, e.g., at the left of the peak frequencies. Fractional variability amplitudes are F_var_~40% for both spectroscopic and photometric observations. Variations of {alpha} indicate variations of relativistic electron distribution producing the optical spectra.
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