- ID:
- ivo://CDS.VizieR/J/A+A/466/181
- Title:
- BVI photometry of Whiting 1
- Short Name:
- J/A+A/466/181
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recently Carraro (2005ApJ...621L..61C) drew attention to the remarkable star cluster Whiting 1, showing that it lies at about 40kpc from the Sun and is therefore unquestionably a member of the Galactic halo (l=-60.6{deg}). Its Color Magnitude Diagram (CMD) indicated that Whiting 1 is very young (~5Gyrs) for a globular cluster. It is highly likely that Whiting 1 is originated in a dwarf galaxy that has since been disrupted by the Milky Way. The main purpose of the present study is to better constrain the properties of Whiting 1, and assess whether it belongs to a stellar stream from the Sagittarius Dwarf Spheroidal Galaxy (Sgr dSph). Deep CCD photometry in the BVI pass-band obtained with the VLT is used to improve the quality of the CMD, and provide more solid estimates of the cluster distance and age, while high resolution spectra of three evolved stars obtained at Magellan is used to derive the cluster kinematics and analyze its possible membership to the Sgr dSph. We demonstrate that - independently on the Halo model employed - Whiting 1 is part of the trailing stream of the Sgr dSph. We derive a new age estimate of 6.5^+1.0^_-0.5_Gyr, and a smaller heliocentric distance of 29.4^+1.8^_-2.0_kpc. The number of globular clusters confirmed to be members of Sgr dSph is now 6. Among these clusters, Whiting 1 is particularly interesting, being the youngest and one of the most metal rich. The existence of Whiting 1 shows how the Sgr dSph was able to form star clusters for a period at least of 6Gyr.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/360/529
- Title:
- BVI photometry of 4 young open clusters
- Short Name:
- J/A+A/360/529
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD observations in the B, V, and I passbands obtained for stars in the fields of the open clusters Pismis 22, NGC 6178, NGC 6216, and Ruprecht 130, projected not far from the Galactic centre (|l|<30{deg}, |b|<2{deg}). The sample consists of about 790 stars reaching down to V~18-19mag. From the analysis of the colour magnitude diagrams, we confirmed the physical reality of the clusters and derived their reddening, distance and age. In addition, we obtained flux-calibrated integrated spectra in the range 3500-9200{AA} for the cluster sample. The equivalent widths of the Balmer lines provided us with age estimates, while the comparison with template spectra allowed us to derive both foreground reddening and age. The photometric and spectroscopic results reveal that the four studied objects are young open clusters with ages ranging between 35 and 50Myr. The clusters, located between 1.0kpc and 4.3kpc from the Sun, are affected by different amounts of interstellar visual absorption (0.6=~A_v_=~6.0).
- ID:
- ivo://CDS.VizieR/J/MNRAS/375/1220
- Title:
- BVI photometry of young stars in 10 clusters
- Short Name:
- J/MNRAS/375/1220
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have selected pre-main-sequence (PMS) stars in 12 groups of notional ages ranging from 1 to 35Myr, using heterogeneous membership criteria. Using these members we have constructed empirical isochrones in V, V-I colour-magnitude diagrams. This allows us to identify clearly the gap between the radiative main sequence and the convective PMS (the RC gap). We follow the evolution of this gap with age and show that it can be a useful age indicator for groups less than =15 Myr old. We also observe a reduction in absolute spreads about the sequences with age. Finally, the empirical isochrones allow us to place the groups in order of age, independently of theory. The youngest groups can be collated into three sets of similar ages. The youngest set is the ONC, NGC 6530 and IC 5146 (nominally 1Myr); next Cep OB3b, NGC 2362, Ori and NGC 2264 (nominally 3Myr); and finally Ori and IC 348 (nominally 45Myr). This suggests Cep OB3b is younger than previously thought, and IC 348 older. For IC 348 the stellar rotation rate distribution and fraction of stars with discs imply a younger age than we derive. We suggest this is because of the absence of O-stars in this cluster, whose winds and/or ionizing radiation may be an important factor in the removal of discs in other clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/138/680
- Title:
- BVI TX Cnc light curves
- Short Name:
- J/AJ/138/680
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present B-, V-, and I-band CCD photometry of the W UMa-type binary system TX Cnc, which is a member star of the Praesepe open cluster. Based on the observations, new ephemeris and a revised photometric solution of the binary system were derived.
- ID:
- ivo://CDS.VizieR/J/PAZh/35/44
- Title:
- BV light curves of 33 ASAS-3 Cepheids
- Short Name:
- J/PAZh/35/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cepheids, the principal distance indicators, point to the existence of two inner Galactic spiral arms in the immediate solar neighborhood (within 5kpc). However, the available Cepheids are clearly insufficient for a detailed study of the structure of these arms. Fortunately, southern-sky monitoring (the ASAS project) has led to the discovery of many new variable stars, more than one thousand of which have been identified as possible Cepheids. To improve the classification and to construct reliable light curves for new Cepheids, we have begun their regular photometric observations. Here, we present the first results: 1192 photoelectric BVIc observations were performed for 33 classicalCepheidswith the 76-cm telescope of the South-African Astronomical Observatory (SAAO, the South-African Republic) from December 2006 to January 2008.We provide tables of observations and V light and B-V and V-Ic color curves. The new observations together with ASAS-3 data have been used to improve the elements of the light variations.
- 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/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.
