- ID:
- ivo://CDS.VizieR/J/PASP/97/753
- Title:
- BVR CCD photometry on NGC 1777
- Short Name:
- J/PASP/97/753
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photographic (B and V) and CCD (B, V, and R) photometry of stars in the remote LMC cluster NGC 1777, and integrated UBV photometry of the inner part of the cluster. A comparison of the results from the two techniques reveals large (~0.20m) systematic differences which we attribute to the difficulty of faint photometry. The photographic calibration depended on images produced by a Racine wedge, while the CCD calibration was accomplished in a manner analogous to photoelectric photometry. The stellar photometry provides a C-M diagram to V=21.5 which includes an evolved main sequence and a well-populated giant branch. A variety of methods, including comparisons of the observations to two sets of isochrones, allows us to estimate the cluster age as 0.9+/-0.2x10^9^ years. However we are only able to estimate the metallicity ([Fe/H]) crudely as -0.7+/-0.5. The C-M diagrams of the field in three regions near NGC 1777 indicate the presence of stars in the age range 1x10^9^ to >=3x10^9^ years, although we are unable to discern whether a mixture of two or more distinct populations or a continuous distribution of field-star ages is responsible for this spread.
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- ID:
- ivo://CDS.VizieR/J/ApJ/811/32
- Title:
- BVRcIcJHK and X-ray LCs of the U Sco nova
- Short Name:
- J/ApJ/811/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The recurrent nova U Scorpii most recently erupted in 2010. Our collaboration observed the eruption in bands ranging from the Swift XRT and UVOT w2 (193nm) to K-band (2200nm), with a few serendipitous observations stretching down to WISE W2 (4600nm). Considering the time and wavelength coverage, this is the most comprehensively observed nova eruption to date. We present here the resulting multi-wavelength light curve covering the two months of the eruption as well as a few months into quiescence. For the first time, a U Sco eruption has been followed all the way back to quiescence, leading to the discovery of new features in the light curve, including a second, as-yet-unexplained, plateau in the optical and near-infrared. Using this light curve we show that U Sco nearly fits the broken power law decline predicted by Hachisu & Kato (2006ApJS..167...59H), with decline indices of -1.71+/-0.02 and -3.36+/-0.14. With our unprecedented multi-wavelength coverage, we construct daily spectral energy distributions and then calculate the total radiated energy of the eruption, E_rad_=6.99^+0.83^_-0.57_x10^44^erg. From that, we estimate the total amount of mass ejected by the eruption to be m_ej_=2.10^+0.24^_-0.17_x10^-6^M_{sun}_. We compare this to the total amount of mass accreted by U Sco before the eruption, to determine whether the white dwarf undergoes a net mass loss or gain, but find that the values for the amount of mass accreted are not precise enough to make a useful comparison.
- ID:
- ivo://CDS.VizieR/J/AJ/157/207
- Title:
- BVR_c_I_c_ light curve observations for VZ Lib
- Short Name:
- J/AJ/157/207
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- VZ Lib is a southern triple-lined system. By analyzing all available times of light minima, orbital period changes are revisited in detail. We discovered that the observed-calculated (O-C) curve shows a long-term period decrease at a rate of dP/dt=-2.25x10^-7^ days/yr, revealing a mass transfer from the more massive component to the less massive one. A cyclic variation covering more than three cycles was discovered, which was analyzed for the light-travel-time effect via the presence of the tertiary companion. The cyclic variation has a short period of 2.96 (+/-0.04) yr and a small semiamplitude of 0.0039 (+/-0.0004) days. The mass of the third body was determined to be M_3_sini_3_=0.52 (+/-0.07) M_{sun}_ and an orbital semimajor axis shorter than 1.93 (+/-0.31) au was obtained. Orbital properties of this close-in companion should provide valuable information on the formation of close binaries and stellar dynamical interaction. New complete BVR_c_I_c_ light curves of VZ Lib were obtained and modeled with the Wilson-Devinney code. The light curves show a small but significant O'Connell effect that was not detectable in 1981 and 2007 but in 2004, so we derived a new photometric solution with assuming spot and a third light in the system. It is found that the light-curve subtype changed from A-type to W-type, which was possibly caused by a dark spot on the massive component. Our photometric solutions are in agreement with the spectroscopic results given by previous authors.
- ID:
- ivo://CDS.VizieR/J/AJ/160/175
- Title:
- 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.
- ID:
- ivo://CDS.VizieR/J/other/NewA/31.65
- Title:
- BVRcIc light curves of LU Lac
- Short Name:
- J/other/NewA/31.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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.
- ID:
- ivo://CDS.VizieR/J/A+AS/117/475
- Title:
- BVRcIc photometry of 10 blazars
- Short Name:
- J/A+AS/117/475
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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>.
- ID:
- ivo://CDS.VizieR/J/MNRAS/385/361
- Title:
- BVRcIc photometry of NGC 821 globular clusters
- Short Name:
- J/MNRAS/385/361
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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.
- ID:
- ivo://CDS.VizieR/J/MNRAS/387/344
- Title:
- BVRcIC photometry of V2615 Oph
- Short Name:
- J/MNRAS/387/344
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/570/A100
- Title:
- BVRc light curves of 5 CoRoT RR Lyrae stars
- Short Name:
- J/A+A/570/A100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/652/458
- Title:
- BVRH{alpha} photometry of candidates Be stars
- Short Name:
- J/ApJ/652/458
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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.
