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2021. Photometry and spectroscopy of NGC 6520
ID:
ivo://CDS.VizieR/J/AJ/147/7
Title:
Photometry and spectroscopy of NGC 6520
Short Name:
J/AJ/147/7
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use CCD and photoelectric photometry with Stromgren filters along with medium resolution spectra to investigate NGC 6520, an open cluster very nearly in the direction of the galactic center. We find an age of 60Myr, a distance of 2kpc, and an average reddening E(b-y)=0.295, which increases toward the south. The average heliocentric radial velocity of the B stars is -29km/s, while the velocity of the nearby Barnard 86 is about 0 (heliocentric; -11km/s compared to the LSR). This velocity difference amounts to about 1.8kpc since the cluster formed, implying that it is extremely doubtful NGC6520 is related to Barnard 86.
2022. Photometry and spectroscopy of RN LMC 1968
ID:
ivo://CDS.VizieR/J/MNRAS/491/655
Title:
Photometry and spectroscopy of RN LMC 1968
Short Name:
J/MNRAS/491/655
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a comprehensive review of all observations of the eclipsing recurrent Nova LMC 1968 in the Large Magellanic Cloud which was previously observed in eruption in 1968, 1990, 2002, 2010, and most recently in 2016. We derive a probable recurrence time of 6.2+/-1.2yr and provide the ephemerides of the eclipse. In the ultraviolet-optical-IR photometry the light curve shows high variability right from the first observation around 2 d after eruption. Therefore no colour changes can be substantiated. Outburst spectra from 2016 and 1990 are very similar and are dominated by H and He lines longward of 2000{AA}. Interstellar reddening is found to be E(B-V)=0.07+/-0.01. The super soft X-ray luminosity is lower than the Eddington luminosity and the X-ray spectra suggest the mass of the white dwarf (WD) is larger than 1.3M_{sun}_. Eclipses in the light curve suggest that the system is at high orbital inclination. On day 4 after the eruption a recombination wave was observed in FeII ultraviolet absorption lines. Narrow-line components are seen after day 6 and explained as being due to reionization of ejecta from a previous eruption. The UV spectrum varies with orbital phase, in particular a component of the HeII 1640{AA} emission line, which leads us to propose that early-on the inner WD Roche lobe might be filled with a bound opaque medium prior to the re-formation of an accretion disc. Both this medium and the ejecta can cause the delay in the appearance of the soft X-ray source.
2023. Photometry and spectroscopy of stars in Cz 30
ID:
ivo://CDS.VizieR/J/AJ/150/200
Title:
Photometry and spectroscopy of stars in Cz 30
Short Name:
J/AJ/150/200
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new photometric and spectroscopic data of the old open cluster Czernik 30. Wide field BVI photometry allows us to correct for the high field contamination by statistical subtraction to produce a color-magnitude diagram (CMD) that clearly reveals the cluster sequence. From spectra of stars in the cluster field obtained with the Hydra spectrograph on the Wisconsin-Indiana-Yale-NOAO 3.5m telescope we determine a mean cluster velocity of +79.9+/-1.5km/s and provide membership information that helps further define the cluster giant branch and red clump. Stellar abundances for the brighter giants in the cluster indicate a mean metallicity of [Fe/H]=-0.2+/-0.15. Fitting theoretical isochrones to the CMD we determine the following properties of Czernik 30: age=2.8+/-0.3Gyr, (m-M)_v_=14.8+/-0.1, E(B-V)=0.24+/-0.06, and E(V-I)=0.36+/-0.04. Czernik 30 is an old, sub-solar metallicity cluster located at a Galactocentric radius of R_gc_~13.3kpc. Given its age and position just beyond the transition to a flat abundance gradient seen in the open cluster population, Czernik 30 provides an interesting target for future observations.
2024. Photometry and velocities of 1SWASP J093010A and B
ID:
ivo://CDS.VizieR/J/AJ/147/104
Title:
Photometry and velocities of 1SWASP J093010A and B
Short Name:
J/AJ/147/104
Date:
21 Oct 2021
Publisher:
CDS
Description:
Among quadruples or higher multiplicity stars, only a few doubly eclipsing binary systems have been discovered. They are important targets for understanding the formation and evolution of multiple stellar systems because we can obtain accurate stellar parameters from photometric and spectroscopic studies. We present the observational results of this kind of rare object, 1SWASP J093010.78+533859.5, for which the doubly eclipsing feature had been detected previously from the SuperWASP photometric archive. Individual point-spread function photometry for two objects with a separation of about 1.9" was performed for the first time in this study. Our time-series photometric data confirms the finding of Lohr et al. that the bright object A is an Algol-type detached eclipsing binary and the fainter B is a W UMa-type contact eclipsing. Using high-resolution optical spectra, we obtained well-defined radial velocity variations of system A. Furthermore, stationary spectral lines were detected that must have originated from a further, previously unrecognized stellar component. It was confirmed by the third object contribution from the light-curve analysis. No spectral feature of system B was detected, probably due to motion blur by long exposure times. We obtained the binary parameters and the absolute dimensions of systems A and B from light-curve synthesis with and without radial velocities, respectively. The primary and secondary components of system A have a spectral type of K1 and K5 main sequences, respectively. Two components of system B have nearly the same type of K3 main sequence. Light variations for both binaries are satisfactorily modeled by using two-spot models with one starspot on each component. We estimated the distances to systems A and B individually. Two systems may have similar distances of about 70 pc and seem to be gravitationally bound with a separation of about 130 AU. In conclusion, we suggest that 1SWASP J093010.78+533859.5 is a quintuple stellar system with a hierarchical structure of a triple system A(ab)c and a binary system B(ab).
2025. Photometry catalogs for the Lockman Hole
ID:
ivo://CDS.VizieR/J/ApJS/198/1
Title:
Photometry catalogs for the Lockman Hole
Short Name:
J/ApJS/198/1
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present broadband photometry and photometric redshifts for 187611 sources located in ~0.5deg^2^ in the Lockman Hole area. The catalog includes 388 X-ray-detected sources identified with the very deep XMM-Newton observations available for an area of 0.2deg^2^. The source detection was performed on the Rc-, z'-, and B-band images and the available photometry is spanning from the far-ultraviolet to the mid-infrared, reaching in the best-case scenario 21 bands. Astrometry corrections and photometric cross-calibrations over the entire data set allowed the computation of accurate photometric redshifts. Special treatment is undertaken for the X-ray sources, the majority of which are active galactic nuclei (AGNs). For normal galaxies, comparing the photometric redshifts to the 253 available spectroscopic redshifts, we achieve an accuracy of {sigma}_{Delta}z/(1+z)_=0.036, with 12.6% outliers. For the X-ray-detected sources, compared to 115 spectroscopic redshifts, the accuracy is {sigma}_{Delta}z/(1+z)_=0.069, with 18.3% outliers, where the outliers are defined as sources with |z_phot_-z_spec_|>0.15x(1+z_spec_).
2026. Photometry identification of cool white dwarfs
ID:
ivo://CDS.VizieR/J/AJ/128/1825
Title:
Photometry identification of cool white dwarfs
Short Name:
J/AJ/128/1825
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the use of a narrowband DDO51 filter for photometric identification of cool white dwarfs. We report photometric observations of 30 known cool white dwarfs with temperatures ranging from 10,000K down to very cool temperatures (<=3500K). Follow-up spectroscopic observations of a sample of objects selected using this filter and our photometric observations show that DDO51 filter photometry can help select cool white dwarf candidates for follow-up multiobject spectroscopy by rejecting 65% of main-sequence stars with the same broadband colors as the cool white dwarfs. This technique is not selective enough to efficiently feed single-object spectrographs. We present the white dwarf cooling sequence using this filter. Our observations show that very cool white dwarfs form a sequence in the r-DDO versus r-z color-color diagram and demonstrate that significant improvements are needed in white dwarf model atmospheres.
2027. Photometry in field of RX J004404.8+411820
ID:
ivo://CDS.VizieR/J/A+A/389/439
Title:
Photometry in field of RX J004404.8+411820
Short Name:
J/A+A/389/439
Date:
21 Oct 2021
Publisher:
CDS
Description:
We propose the first association of an optical counterpart with a luminous supersoft X-ray source in M31, RX J0044.0+4118, observed with ROSAT in July 1991. The PSPC position is at 1.644 angular distance from a candidate nova in outburst in September of 1990. This is interesting because the incidence of classical novae among supersoft X-ray sources is an open question. The proposed optical counterpart was measured at R~=17.7 in September of 1990, and it had faded to R>19.2 when it was observed again after 70 days. The light curve was too sparsely monitored for definite conclusions on the speed class of the nova. No other variable objects with V<23.5 were found in the ROSAT spatial error box. We evaluate that the probability that a classical or recurrent nova was in outburst in the ROSAT error box in the few years preceding the observation is very small, so the proposed identification is meaningful. We also show evidence that the associated supersoft X-ray source turned off in the third year after the outburst.
2028. Photometry in 6 galactic open star clusters
ID:
ivo://CDS.VizieR/J/PAZh/36/16
Title:
Photometry in 6 galactic open star clusters
Short Name:
J/PAZh/36/16
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of our BVRcIc CCD photometry for six Galactic open star clusters toward the Perseus spiral arm performed at the Special Astrophysical Observatory of the Russian Academy of Sciences.
2029. Photometry in globular clusters. I. NGC 1851
ID:
ivo://CDS.VizieR/J/AJ/148/27
Title:
Photometry in globular clusters. I. NGC 1851
Short Name:
J/AJ/148/27
Date:
21 Oct 2021
Publisher:
CDS
Description:
The analysis of multiple populations (MPs) in globular clusters (GCs) has become a forefront area of research in astronomy. Multiple red giant branches (RGBs), subgiant branches (SGBs), and even main sequences (MSs) have now been observed photometrically in many GCs, while broad abundance distributions of certain elements have been detected spectroscopically in most, if not all, GCs. UV photometry has been crucial in discovering and analyzing these MPs, but the Johnson U and the Stromgren and Sloan u filters that have generally been used are relatively inefficient and very sensitive to reddening and atmospheric extinction. In contrast, the Washington C filter is much broader and redder than these competing UV filters, making it far more efficient at detecting MPs and much less sensitive to reddening and extinction. Here, we investigate the use of the Washington system to uncover MPs using only a 1 m telescope. Our analysis of the well-studied GC NGC 1851 finds that the C filter is both very efficient and effective at detecting its previously discovered MPs in the RGB and SGB. Remarkably, we have also detected an intrinsically broad MS best characterized by two distinct but heavily overlapping populations that cannot be explained by binaries, field stars, or photometric errors. The MS distribution is in very good agreement with that seen on the RGB, with ~30% of the stars belonging to the second population. There is also evidence for two sequences in the red horizontal branch, but this appears to be unrelated to the MPs in this cluster. Neither of these latter phenomena have been observed previously in this cluster. The redder MS stars are also more centrally concentrated than the blue MS. This is the first time MPs in an MS have been discovered from the ground, and using only a 1 m telescope. The Washington system thus proves to be a very powerful tool for investigating MPs, and holds particular promise for extragalactic objects where photons are limited.
2030. Photometry in open cluster NGC 5822
ID:
ivo://CDS.VizieR/J/PASP/105/78
Title:
Photometry in open cluster NGC 5822
Short Name:
J/PASP/105/78
Date:
21 Oct 2021
Publisher:
CDS
Description:
The study presents photoelectric photometry of stars in NGC 5822 on the UBVR and DDO systems. The BV data are employed to calibrate a photographic survey of the cluster, while UBV and DDO data are used to constrain the cluster reddening and metallicity. Taken in conjunction with previous photometric analysis, it is found that the cluster has a reddening of 0.15+/-0.015(pe) as defined for the stars at the turnoff, and a metallicity relative to the sun of -0.15+/-0.05(pe).