Near infrared light variations of CP stars

Catalano, F. A.; Leone, F.; Kroll, R.

doi:10.1051/aas:1998423

Cited by 16 publications

(13 citation statements)

References 22 publications

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“…In addition, they found no photometric variability with an amplitude larger than 0.05 mag for their sample of stars. However, later on, variability in the NIR (JHK) with the same period, spectrum, and magnetic field variations as the optical light was detected, for example, for several stars of the SiSrCrEu subgroup (Catalano et al 1998). The amplitudes range from 0.04 to 0.002 mag.…”

Section: Introductionmentioning

confidence: 90%

Chemically peculiar stars as seen with 2MASS

Herdin¹,

Paunzen

Netopil

2015

A&A

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Context. The chemically peculiar (CP) stars of the upper main sequence are well suited for investigating the impact of magnetic fields and diffusion on the surface layers of slowly rotating stars. They can even be traced in the Magellanic Clouds and are important to the understanding of the stellar formation and evolution. Aims. A systematic investigation of the near-infrared (NIR), 2MASS JHK s , photometry for the group of CP stars has never been performed. Nowadays, there is a great deal of data available in the NIR that reach very large distances. It is therefore very important for CP stars to be unambiguously detected in the NIR region and for these detections to be used to derive astrophysical parameters (age and mass) by applying isochrone fitting. Furthermore, we investigated whether the CP stars behave in a different way to normal-type stars in the various photometric diagrams. Methods. For our analysis, we carefully compiled a sample of CP and apparently normal (non-peculiar) type stars. Only stars for which high-quality (i.e. with low error levels), astrometric, and photometric data are available were chosen. In total, 639 normal and 622 CP stars were selected and further analysed. All stars were dereddened and calibrated in terms of the effective temperature and absolute magnitude (luminosity). Finally, isochrone fitting was applied. Results. No differences in the astrophysical parameters derived from 2MASS and Johnson UBV photometry were found. Furthermore, no statistical significant deviations from the normal type stars within several colour-colour and colour-magnitude diagrams were discovered. Therefore, it is not possible to detect new CP stars with the help of the photometric 2MASS colours only. A new effective temperature calibration, valid for all CP stars, using the (V − K S ) 0 colour was derived.

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Section: Introductionmentioning

confidence: 90%

Chemically peculiar stars as seen with 2MASS

Herdin¹,

Paunzen

Netopil

2015

A&A

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“…Thus, light maxima show the phase of the H eff extrema and light minima have the null field phases. Much simpler are the near infrared light curves determined by Catalano et al (1998) whose sinusoidal variation is almost in phase with H eff (Fig. 3).…”

Section: Sex = Hd 90044 = Hr 4082 = Hip 50885mentioning

confidence: 97%

“…Adelman (1997) and Hipparcos light curve of 25 Sex. Near infrared light curves are from Catalano et al (1998). Solid lines represent a leastsquare fitting of data with Eq.…”

Section: (Triangles) Crosses Represent the Ten Colourmentioning

confidence: 99%

Spectropolarimetric measurements of the mean longitudinal magnetic field of chemically peculiar stars

Leone

Catanzaro

2001

A&A

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Abstract. For a sample of chemically peculiar stars, we report time-resolved measurements of the effective magnetic field which were obtained with the spectropolarimetry operating at the Catania Astrophysical Observatory. These observations are combined with data from the literature for better pointing out that periodic magnetic variability which characterises this class of stars. Periods given in the literature have been checked and, if possible, redetermined, not only by means of the magnetic measurements but referring also to the Hipparcos photometry. The variability of the effective magnetic field of the already known magnetic star 25 Sex is pointed out for the first time. As to the suspected magnetic chemically peculiar star EP UMa, our measurements confirm that this is really a magnetic star and we indicate a possible variability period. The accuracy of the variability period for CS Vir and FF Vir is improved. The suggestion that light variability is due to the re-distribution of ultraviolet flux towards the visible wavelengths in metal rich regions, which are not homogeneously distributed on the stellar surface, appears not always and straightly valid. Local line-blocking is certainly important in the case of CS Vir and a direct influence of the magnetic field on the infrared photometric variability cannot be ruled out for 25 Sex.

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“…The validity of this period has been recently confirmed by Adelman (1997) and by near IR bands J, H, and K observations by Catalano, Leone & Kroll (1998). It was also confirmed by magnetic data carried out by Bohlender et al (1993) and Leone & Catanzaro (2001).…”

Section: Hd 90044 (= Hr 4082 = Hip 50885 = 25 Sex)mentioning

confidence: 54%

Variability of the HeIλ5876 Å line in early type chemically peculiar stars. II

Catanzaro¹,

Leone

2003

Astron Nachr

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Abstract. To try to understand the behavior of helium variability in Chemically Peculiar stars, we continued our on-going observational campaign started by Catanzaro, Leone & Catalano (1999). In this paper we present a new set of time resolved spectroscopic observations of the HeI5876Å line for a sample of 10 stars in the spectral range B3 -A2 and characterized by different overabundances. This line does not show variability in two stars: HD 77350 and HD 175156. It shows instead an equivalent width variation in phase with the Hipparcos light curve for two stars: HD 79158 and HD 196502. Antiphase variations have been found in 4 stars of our sample, namely: HD 35502, HD 124224, HD 129174 and HD 142990. Nothing we can say about HD 115735 because of the constancy of Hipparcos photometric data, while no phase relation has been observed for HD 90044.In the text we discuss the case of HD 175156, according to photometric calibration and our spectroscopic observations we rule out the membership of this star to the main sequence chemically peculiar stars. We confirm the results obtained in the previous paper for which phase relations between light, spectral and magnetic variations are not dependent on stellar spectral type or peculiarity subclass.

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Near infrared light variations of CP stars

Abstract: Abstract. Twelve magnetic Chemically Peculiar (CP2) stars of the SiSrCrEu subgroup mostly brighter than the 7.5 visual magnitude have been investigated in the infrared at 1.25, 1.6 and 2.2 µ.

Cited by 16 publications

References 22 publications

Chemically peculiar stars as seen with 2MASS

Chemically peculiar stars as seen with 2MASS

Spectropolarimetric measurements of the mean longitudinal magnetic field of chemically peculiar stars

Variability of the HeIλ5876 Å line in early type chemically peculiar stars. II

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