J/other/AstBu/76.163 Ori OB1 CP stars magnetic fields. V. (Romanyuk+, 2021) ================================================================================ Magnetic Fields of CP Stars in the Orion OB1 Association. V. Stars of Subgroups (c) and (d). Romanyuk I.I., Semenko E.A., Moiseeva A.V., Yakunin I.A., Kudryavtsev D.O. =2021AstBu..76..163R (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Magnetic fields ; Spectroscopy ; Stars, Ap; Stars, Bp ; Stars, peculiar ; Stars, standard Keywords: magnetic field - stars: chemically peculiar Abstract: The paper presents the results of magnetic field measurements of 27 chemically peculiar stars in subgroups (c) and (d) of the Orion OB1 association. In total, more than 140 circularly polarized spectra were obtained and measured in the period from 2013 to 2020. An analysis of the results showed that 13 out of 24 CP stars in subgroup (c) have a magnetic field. At the same time, no field of a significant strength was found in any of the three CP stars in subgroup (d). We found that the occurrence of magnetic stars in subgroup (c), whose average age is approximately 5Myr, lies in the middle between the occurrence of magnetic stars in subgroups (a) with an age of 10 Myr and (b), whose age is about 2Myr. Our results indicate a sharp decrease in the occurrence of magnetic CP stars and a simultaneous decrease in their magnetic field with age. The data obtained with the example of the Orion OB1 association generally support the theory of the fossil origin of the magnetic field of chemically peculiar stars; however, the process of the field formation itself can have a number of features manifesting observationally. Description: We present magnetic field measurements for 27 chemically peculiar (CP) stars of subgroup (c,d) in the Orion OB1 association. Data was obtained at the Main Stellar Spectrograph of the Russian 6-m telescope. We got 151 zeeman spectra for 27 stars. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file stars.dat 36 27 List of studied stars orib1c.dat 61 151 Magnetic field measurements for 27 chemically peculiar stars -------------------------------------------------------------------------------- See also: J/other/AstBu/74.55 : Ori OB1 CP stars magnetic fields. III. (Romanyuk+, 2019) J/other/AstBu/76.163 : Ori OB1 CP stars magnetic fields. V. (Romanyuk+, 2021) Byte-by-byte Description of file: stars.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 9 A9 --- Name HD designation 12- 13 I2 h RAh Right ascension (J2000) 15- 16 I2 min RAm Right ascension (J2000) 18- 21 F4.1 s RAs Right ascension (J2000) 23 A1 --- DE- Declination sign (J2000) 24- 25 I2 deg DEd Declination (J2000) 27- 28 I2 arcmin DEm Declination (J2000) 30- 33 F4.1 arcsec DEs Declination (J2000) 35- 36 I2 --- Nobs Number of observations in orib1c.dat file -------------------------------------------------------------------------------- Byte-by-byte Description of file: orib1c.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 9 A9 --- Name HD designation 12- 19 F8.3 --- MJD MJD (Modified Heliocentric Julian Date) 24- 26 I3 --- S/N ? Signal-to-noise ratio 30- 34 I5 gauss Be(z) Longitudinal magnetic field, measured by the standard Babcock method 37- 41 I5 gauss e_Be(z) rms uncertainty on Be(z) 44- 48 I5 gauss Be(r) ? Longitudinal magnetic field, measured by the regression method 51- 54 I4 gauss e_Be(r) ? rms uncertainty on Be(r) 56- 61 I6 gauss Be(h) ? Longitudinal magnetic field, measured by the core of the hydrogen H{beta} line -------------------------------------------------------------------------------- Acknowledgements: Anastasiya Moiseeva, agreana(at)mail.ru References: Romanyuk et al., Paper I 2016AstBu..71..436R Romanyuk et al., Paper II 2017AstBu..72..165R Romanyuk et al., Paper III 2019AstBu..74...55R, Cat. J/other/AstBu/74.55 Romanyuk et al., Paper IV 2021AstBu..76...39R, Cat. J/other/AstBu/76.39 ================================================================================ (End) Iosif Romanyuk [Astrophysical Bull.], Patricia Vannier [CDS] 05-Aug-2021