- ID:
- ivo://CDS.VizieR/J/A+AS/125/65
- Title:
- uvby photometry of 4 CP stars
- Short Name:
- J/A+AS/125/65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Differential Stroemgren uvby photometric observations from the Four College Automated Photoelectric Telescope are presented for four magnetic chemically peculiar stars. Comparison with uvby photometry of Pedersen & Thomsen for HD 37776 yields an improved period of 1.538675 days. New periods of 15.0305 days and 18.065 days are found for the sharp-lined stars HR 2258 and HR 6958, respectively, rather than one of their aliases. For HR 6958 each color shows a slightly different time of maximum. Comparison of the four color photometry of 108 Aqr taken during the fall of 1995 which well covers the period shows the presence of a secondary minimum near primary maximum in u, v, and b. Comparison with published photometry indicates indicates that subtle changes in the shapes of the light curves have occurred suggesting that this star might be precessing.
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- ID:
- ivo://CDS.VizieR/J/A+A/390/1023
- Title:
- uvby photometry of 4 CP stars
- Short Name:
- J/A+A/390/1023
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Differential Stroemgren uvby observations from the Four College Automated Photoelectric Telescope (FCAPT) are presented for the CP stars HR 149 and HR 7911 and the mCP stars HD 32966 and HD 171782. The Hg-Mn star HR 149 is found to be constant while HR 7911 with a period of 5.9617 days probably has a component which is a magnetic CP star. Improved periods were derived for HD 32966 and HD 171782 of 3.0927 and 4.4674 days, respectively. The former is a rather large amplitude mCP star. Both have at least one light curve different in shape from the others observed.
- ID:
- ivo://CDS.VizieR/J/A+AS/106/333
- Title:
- uvby photometry of four CP stars
- Short Name:
- J/A+AS/106/333
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Differential Stroemgren uvby photometric observations from the Four College Automated Photoelectric Telescope of four chemical peculiar stars is presented and analyzed. The peculiar Hg-Mn star {alpha} And is found not to be a photometric variable within the errors of measurement contrary to some published studies. Observations of the magnetic CP star HD 184905 were used to refine the zero epoch and the period which was found to be 1.85435 days. Our photometry and that of Morrison & Wolff are generally quite similar. We find evidence for two sub-minima within the broad minimum in both u and y. The cool magnetic CP star HR 8216 is non-variable in agreement with previous studies that suggested it was constant or a very long period variable. The CP star HR 8434 has a period of 1.43242 days and shows a generally in phase variation of u, v, b, and y. The light curves have two nearly equally maximum and a sharp minimum. The largest amplitude is for u, 0.085 mag.
- ID:
- ivo://CDS.VizieR/J/A+A/429/317
- Title:
- uvby photometry of 1 HgMn and 3 mCP stars
- Short Name:
- J/A+A/429/317
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Differential Stroemgren uvby observations from the Four College Automated Photoelectric Telescope are presented for the magnetic CP (mCP) stars HR 2258, MW Vul, and HR 9017 and the HgMn star 46 (rho) Aqr.
- ID:
- ivo://CDS.VizieR/J/A+AS/123/445
- Title:
- uvby photometry of metallic & Hg-Mn stars
- Short Name:
- J/A+AS/123/445
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Differential Stroemgren uvby photometric observations from the 0.75-m Four College Automated Photoelectric Telescope were obtained for three metallic-line and three Mercury-Manganese stars. None were found to be variable. These sharp-lined stars may not be the best tests for class variability as their polar axes are pointed towards the earth. Each presents essentially the same visible hemisphere as it rotates.
- ID:
- ivo://CDS.VizieR/J/A+AS/133/197
- Title:
- uvby Photometry of 33 Tau, HD 50169 and HR 7786
- Short Name:
- J/A+AS/133/197
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Differential Stroemgren uvby photometric observations from the Four College Automated Photoelectric Telescope are presented for the ellipsoidal variable 33 Tauri, and the magnetic Chemically Peculiar stars HD 50169 and HR 7786. We confirm that Hube's period of 2.975272 days for 33 Tau is correct. HD 50169 is a constant MCP star. HR 7786 is a large amplitude class member confirming Winzer's discovery, but its period is 8.5297 days. Its comparison star, HR 7721, a spectroscopic binary B7 V star, is variable with an amplitude of order 0.1mag, but of indeterminant period. In addition Hipparcos photometry of the comparison and check stars for early type stars whose photometry is being obtained with the FCAPT is reviewed to ascertain the stability of these stars.
- ID:
- ivo://CDS.VizieR/J/PAZh/25/209
- Title:
- Variability of peculiar star HD 108
- Short Name:
- J/PAZh/25/209
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of fifteen-year-long observations of optical spectra and BVR photoelectric photometry of the runaway star HD 108 are presented.
- ID:
- ivo://CDS.VizieR/J/MNRAS/442/3604
- Title:
- Variability of the PGa star HD 19400
- Short Name:
- J/MNRAS/442/3604
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of this study is to carry out an abundance determination, to search for spectral variability and for the presence of a weak magnetic field in the typical PGa star HD19400. High-resolution, high signal-to-noise HARPS spectropolarimetric observations of HD19400 were obtained at three different epochs in 2011 and 2013. For the first time, we present abundances of various elements determined using an ATLAS12 model, including the abundances of a number of elements not analysed by previous studies, such as NeI, GaII, and XeII. Several lines of As II are also present in the spectra of HD19400. To study the variability, we compared the behaviour of the line profiles of various elements. We report on the first detection of anomalous shapes of line profiles belonging to Mn, and Hg, and the variability of the line profiles belonging to the elements Hg, P, Mn, Fe, and Ga. We suggest that the variability of the line profiles of these elements is caused by their non-uniform surface distribution, similar to the presence of chemical spots detected in HgMn stars. The search for the presence of a magnetic field was carried out using the moment technique and the SVD method. Our measurements of the magnetic field with the moment technique using 22 MnII lines indicate the potential existence of a weak variable longitudinal magnetic field on the first epoch. The SVD method applied to the MnII lines indicates B_z_=-76+/-25G on the first epoch, and at the same epoch the SVD analysis of the observations using the Fe II lines shows B_z_=-91+/-35G. The calculated false alarm probability values, 0.008 and 0.003, respectively, are above the value 10^-3^, indicating no detection.
- ID:
- ivo://CDS.VizieR/J/A+AS/118/231
- Title:
- Velocities & rotation of CP stars
- Short Name:
- J/A+AS/118/231
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of a systematic project we have determined radial velocities and projected rotational velocities for a sample of 186 chemically peculiar stars which have been observed by the Hipparcos' satellite. The purpose is to provide necessary data to study the space velocities of peculiar stars.
- ID:
- ivo://CDS.VizieR/J/A+A/532/A138
- Title:
- V838 Mon spectrum in 2009
- Short Name:
- J/A+A/532/A138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- V838 Mon erupted at the beginning of 2002. In the course of the outburst the object evolved to low effective temperatures and declined as a very late M-type supergiant. Among various scenarios proposed to explain the nature of the outburst, the most promising is a stellar merger event. We aim at studying the structure and evolution of the object in the decline from the 2002 eruption. We obtained spectroscopic observations of V838 Mon in January-March 2009 with UVES/VLT. The results are analysed and compared with similar observations obtained in October 2005 with HIRES/Keck. The most striking difference between 2009 and 2005 is a complete absence of the B3 V component and of the [FeII] emission lines in 2009. The present spectrum displays only the spectrum of the 2002 eruption remnant. It resembles that of an ~M6 giant, although the molecular bands in V838 Mon are deeper than those in standard stellar spectra of a similar spectral class. Several atomic lines, which displayed P-Cyg profiles in 2005, are now dominated by pure absorptions. Some of these lines, however, show a narrow emission component, which, as we argue, measures the radial velocity of V838 Mon. The resulting heliocentric velocity is 71km/s, which very well agrees with the velocity obtained from SiO maser observations. The atomic lines and the molecular bands show very complex kinematics. In some atomic lines and high-excitation molecular bands we observe matter infalling in the object atmosphere. The infall components were already observed in 2005, but were less pronounced and present in fewer lines than in 2009. We argue that the most negative radial velocity components seen in the resonance atomic lines and in the low-excitation molecular bands were formed in the ejecta of the 2002 eruption. The B3V companion most probably became engulfed in an opaque dusty matter of the 2002 V838 Mon ejecta.
