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5081. Photometry of chemically peculiar stars
ID:
ivo://CDS.VizieR/J/A+AS/128/245
Title:
Photometry of chemically peculiar stars
Short Name:
J/A+AS/128/245
Date:
21 Oct 2021
Publisher:
CDS
Description:
Differential Stroemgren uvby photometric observations from the Four College Automated Photoelectric Telescope are presented for four Chemically Peculiar stars of the upper main sequence: the HgMn star binary AR Aurigae and the magnetic stars 3 Hydrae, 49 Cancri, and BX Bootis. AR Aurigae shows little variability except during the primary and secondary eclipses. The 11.305 day period of Maitzen et al. for 3 Hya is confirmed. A new period of 7.0501 days is found for 49 Cancri while a slightly refined period of 2.88756 days is derived for BX Boo.
5082. Photometry of chemically peculiar stars
ID:
ivo://CDS.VizieR/J/PASP/109/9
Title:
Photometry of chemically peculiar stars
Short Name:
J/PASP/109/9
Date:
21 Oct 2021
Publisher:
CDS
Description:
Differential Stromgren uvby photometric observations from the Four College Automated Photoelectric Telescope of four magnetic Chemically Peculiar stars are used to refine rotational periods and to define the shapes of the light curves. HR 1643 (P=2.73475d) shows large phase variability in all four magnitudes. Theta Aur (P=3.6188d) exhibits large amplitude variations with two components contributing to the minima. For 49 Cam (P=4.28679d), we probably are observing both polar regions and much of the surface. The values for HR 3724 (P=33.984d) confirm Wolff's result that the main variability is in v.
5083. Photometry of CU Vir
ID:
ivo://CDS.VizieR/J/A+A/625/A34
Title:
Photometry of CU Vir
Short Name:
J/A+A/625/A34
Date:
21 Oct 2021
Publisher:
CDS
Description:
CU Vir has been the first main sequence star that showed regular radio pulses that persist for decades, resembling the radio lighthouse of pulsars and interpreted as auroral radio emission similar to that found in planets. The star belongs to a rare group of magnetic chemically peculiar stars with variable rotational period. We study the ultraviolet (UV) spectrum of CU Vir obtained using STIS spectrograph onboard the Hubble Space Telescope (HST) to search for the source of radio emission and to test the model of the rotational period evolution. We used our own far-UV and visual photometric observations supplemented with the archival data to improve the parameters of the quasisinusoidal long-term variations of the rotational period. We predict the flux variations of CU Vir from surface abundance maps and compare these variations with UV flux distribution. We searched for wind, auroral, and interstellar lines in the spectra. The UV and visual light curves display the same long-term period variations supporting their common origin. New updated abundance maps provide better agreement with the observed flux distribution. The upper limit of the wind mass-loss rate is about 10^-12^M_{sun}_/yr. We do not find any auroral lines. We find rotationally modulated variability of interstellar lines, which is most likely of instrumental origin. Our analysis supports the flux redistribution from far-UV to near-UV and visual domains originating in surface abundance spots as the main cause of the flux variability in chemically peculiar stars. Therefore, UV and optical variations are related and the structures leading to these variations are rigidly confined to the stellar surface. The radio emission of CU Vir is most likely powered by a very weak presumably purely metallic wind, which leaves no imprint in spectra.
5084. Photometry of DBS 77-78-102-160-161 regions
ID:
ivo://CDS.VizieR/J/A+A/588/A63
Title:
Photometry of DBS 77-78-102-160-161 regions
Short Name:
J/A+A/588/A63
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report a study of the global properties of some embedded clusters placed in the fourth quadrant of the MilkyWay to clarify some issues related with their location into de Galaxy and their stellar formation processes. We performed BVI photometric observations in the region of DBS 77, 78, 102, 160, and 161 clusters and infrared spectroscopy in DBS 77 region. They were complemented with JHK data from VVV survey combined with 2MASS catalogue, and used mid-infrared information from GLIMPSE catalogue. We also searched for HI data from SGPS and PMN radio surveys, and previous spectroscopic stellar classification. The spectroscopic and photometric information allowed us to estimate the spectral classification of the brightest stars of each studied region. On the other hand, we used the radio data to investigate the interstellar material parameters and the continuum sources probably associated with the respective stellar components. We estimated the basic physical parameters of the clusters (reddening, distance, age, and initial mass function). We searched for HII regions located near to the studied clusters and we analyzed the possible link between them. In the particular case of DBS 160-161 clusters, we identified the HI bubble B332.5-0.1-42 located around them. We found that the mechanical energy injected to the interstellar medium by the more massive stars of this couple of clusters was enough to generate the bubble.
5085. Photometry of DE CVn
ID:
ivo://CDS.VizieR/J/A+A/466/1031
Title:
Photometry of DE CVn
Short Name:
J/A+A/466/1031
Date:
21 Oct 2021
Publisher:
CDS
Description:
Close white dwarf-red dwarf binaries must have gone through a common-envelope phase during their evolution. DE CVn is a detached white dwarf-red dwarf binary with a relatively short (~8.7h) orbital period. Its brightness and the presence of eclipses makes this system ideal for a more detailed study. From a study of photometric and spectroscopic observations of DE CVn we derive the system parameters that we discuss in the framework of common-envelope evolution.
5086. Photometry of 6 deep-contact W UMa
ID:
ivo://CDS.VizieR/J/other/RMxAA/53.235
Title:
Photometry of 6 deep-contact W UMa
Short Name:
J/other/RMxAA/53
Date:
21 Oct 2021
Publisher:
CDS
Description:
Photometric observations in Sloan g' and i' bands of W UMa binaries V0637 Peg, V0473 Cam, CSS J153314.8+560527, CSS J075258.0+382035, V0416 Gem and NSVS 6859986 are presented. Their periods are in the range of 0.26-0.43d. The light curve solutions revealed that the components of each target are almost equal in temperature. The stellar components are of G and K spectral types and undergo total eclipses. All targets have deep-contact configurations with fillout factor f>=0.5. NSVS 6859986 has one o f the biggest value determined until now, f=0.84. We studied the empirical dependencies of fillout factor on the stellar parameters (temperature, period, mass ratio, relative component radii, and luminosity ratio) for a sample of around thirty stars. They are consistent with the theoretical predictions but there are deviations from the common trends.
5087. Photometry of Dorado Group Dwarf Galaxies
ID:
ivo://CDS.VizieR/J/AJ/121/148
Title:
Photometry of Dorado Group Dwarf Galaxies
Short Name:
J/AJ/121/148
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present V and I CCD photometry of suspected low surface brightness dwarf galaxies detected in a survey covering ~2.4 deg^2^ around the central region of the Dorado group of galaxies. The low surface brightness galaxies were chosen based on their sizes and magnitudes at the limiting isophote of 26V{mu}. The selected galaxies have magnitudes brighter than V~20 (MV~-11 for an assumed distance to the group of 17.2 Mpc), with central surface brightnesses {mu}_0_>22.5 Vmag.arcsec^-2^, scale lengths h>2", and diameters >=14" at the limiting isophote. Using these criteria, we identified 69 dwarf galaxy candidates. Four of them are large very low surface brightness galaxies that were detected on a smoothed image, after masking high surface brightness objects. Monte Carlo simulations performed to estimate completeness, photometric uncertainties and to evaluate our ability to detect extended low surface brightness galaxies show that the completeness fraction is, on average, >80% for dwarf galaxies with -17<MV<-10.5 and 22.5<{mu}_0_<25.5 Vmag.arcsec^-2^, for the range of sizes considered by us (D>=14"). The V-I colors of the dwarf candidates vary from -0.3 to 2.3 with a peak on V-I=0.98, suggesting a range of different stellar populations in these galaxies. The projected surface density of the dwarf galaxies shows a concentration toward the group center similar in extent to that found around five X-ray groups and the elliptical galaxy NGC 1132 studied by Mulchaey & Zabludoff (1999ApJ...514..133M), suggesting that the dwarf galaxies in Dorado are probably physically associated with the overall potential well of the group.
5088. Photometry of EXors from Asiago plates
ID:
ivo://CDS.VizieR/J/A+A/602/A99
Title:
Photometry of EXors from Asiago plates
Short Name:
J/A+A/602/A99
Date:
21 Oct 2021
Publisher:
CDS
Description:
EXor objects are young variables that show episodic variations of brightness commonly associated to enhanced accretion outbursts. With the aim of investigating the long-term photometric behaviour of a few EXor sources, we present here data from the archival plates of the Asiago Observatory, showing the Orion field where the three EXors V1118, V1143, and NY are located. A total of 484 plates were investigated, providing a total of more than 1000 magnitudes for the three stars, which cover a period of about 35yrs between 1959 to 1993. We then compared our data with literature data. Apart from a newly discovered flare-up of V1118, we identify the same outbursts already known, but we provide two added values: (i) a long-term sampling of the quiescence phase; and (ii) repeated multi-colour observations (BVRI bands). The former allows us to give a reliable characterisation of the quiescence, which represents a unique reference for studies that will analyze future outbursts and the physical changes induced by these events. The latter is useful for confirming whether the intermittent increases of brightness are accretion-driven (as in the case of V1118), or extinction-driven (as in the case of V1143). Accordingly, doubts arise about the V1143 classification as a pure EXor object. Finally, although our plates do not separate NY Ori and the star very close to it, they indicate that this EXor did not undergo any major outbursts during our 40yrs of monitoring.
5089. Photometry of FG Sge at the ejection state
ID:
ivo://CDS.VizieR/J/PAZh/35/592
Title:
Photometry of FG Sge at the ejection state
Short Name:
J/PAZh/35/592
Date:
21 Oct 2021
Publisher:
CDS
Description:
New photometric observations of the variable star FG Sge, a rapidly evolving planetary nebula nucleus, were performed in 2003-2008. On 230 nights, we obtained 86 UBV and 155 BVRI (or Rc, Ic) magnitude estimates. The maximum amplitude of the V-band light variations was >8mag. Six deep minima and four high maxima were observed.
5090. Photometry of FK Com for 1993-2001
ID:
ivo://CDS.VizieR/J/A+A/374/1049
Title:
Photometry of FK Com for 1993-2001
Short Name:
J/A+A/374/1049
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report 8 years of previously unpublished photometric observations of FK Com. The observations have been carried out between 1993 and 2001 with six different telescopes: 60 cm at Mt. Maidanak (Tashkent, Uzbekistan), Phoenix 10, Wolfgang and Amadeus located in Arizona, USA, and 20cm and 60 cm KVA on La Palma, Spain. Observations contain measurements at the following bands: Johnson U, B, V and R, Bessel R, Cousins I and Stromgren b and y. The observations are differential photometry in respect to the primary comparison star HD 117567. NOTE: Table 1 in the paper contains some small misprints in the Julian dates. Also for Wolfgang and Amadeus the number of observations given in Table1 at each band is slightly less than actually given in Table2c and Table2d. This is caused by accidentally using a limiting error of 0.01 in magnitudes when creating Table 1. In Table 2 the limiting error for Wolfgang and Amadeus is 0.02 mag, as mentioned in the paper itself. In Table2a-e 99.0000 means that no observations were available at that time at that band or that the error in the magnitude was larger than 0.02.