1997A&AS..123..353M


C.D.S. - SIMBAD4 rel 1.7 - 2021.06.21CEST15:32:44

1997A&AS..123..353M - Astron. Astrophys., Suppl. Ser., 123, 353-402 (1997/June-1)

The mean magnetic field modulus of Ap stars.

MATHYS G., HUBRIG S., LANDSTREET J.D., LANZ T. and MANFROID J.

Abstract (from CDS):

We present new measurements of the mean magnetic field modulus of a sample of Ap stars with spectral lines resolved into magnetically split components. We report the discovery of 16 new stars having this property. This brings the total number of such stars known to 42. We have performed more than 750 measurements of the mean field modulus of 40 of these 42 stars, between May 1988 and August 1995. The best of them have an estimated accuracy of 25-30G. The availability of such a large number of measurements allows us to discuss for the first time the distribution of the field modulus intensities. A most intriguing result is the apparent existence of a sharp cutoff at the low end of this distribution, since no star with a field modulus (averaged over the rotation period) smaller than 2.8kG has been found in this study. For more than one third of the studied stars, enough field determinations well distributed throughout the stellar rotation cycle have been achieved to allow us to characterize at least to some extent the variations of the field modulus. These variations are often significantly anharmonic, and it is not unusual for their extrema not to coincide in phase with the extrema of the longitudinal field (for the few stars for which enough data exist about the latter). This, together with considerations on the distribution of the relative amplitude of variation of the studied stars, supports the recently emerging evidence for markedly non-dipolar geometry and fine structure of the magnetic fields of most Ap stars. New or improved determinations of the rotation periods of 9 Ap stars have been achieved from the analysis of the variations of their mean magnetic field modulus. Tentative values of the period have been derived for 5 additional stars, and lower limits have been established for 10 stars. The shortest definite rotation period of an Ap star with magnetically resolved lines is 3.4d, while those stars that rotate slowest appear to have periods in excess of 70 or 75 years. As a result of this study, the number of known Ap stars with rotation periods longer than 30 days is almost doubled. We briefly rediscuss the slow-rotation tail of the period distribution of Ap stars. This study also yielded the discovery of radial velocity variations in 8 stars. There seems to be a deficiency of binaries with short orbital periods among Ap stars with magnetically resolved lines.

Abstract Copyright:

Journal keyword(s): stars: chemically peculiar - stars: magnetic fields - stars: rotation

VizieR on-line data: <Available at CDS (J/A+AS/123/353): table2a table2b table3 table4>

Simbad objects: 42

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Number of rows : 42

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 HD 965 * 00 14 04.0647520206 -00 02 00.101552192   8.94 8.57     ApSrEuCr 60 0
2 V* GR And a2* 00 28 28.5693545697 +32 26 15.879131266   6.99 6.91     A5VpSiSrCr 136 0
3 V* GY And a2* 01 38 31.8241484792 +45 23 58.950612500   6.343 6.380     A2:VpSiSrCrEu 245 0
4 HD 12288 a2* 02 03 30.5093779864 +69 34 56.260586887   7.83 7.74     A0pCrSi 98 0
5 V* V436 And a2* 02 21 02.6743167927 +42 56 38.233069101   7.24 7.27     B8pSr 58 0
6 HD 18078 a2* 02 56 32.0100802361 +56 10 41.427097237   8.50 8.27     ~ 82 0
7 HD 29578 * 04 36 30.7854569859 -54 37 16.079302113   8.82 8.51     ApSrEuCr 33 0
8 HD 47103 * 06 37 44.0719873586 +19 56 55.156680574   9.38 9.16     A 26 0
9 HD 50169 Em* 06 51 59.2282603066 -01 38 40.393959773   9.01 8.98     ApEuSrCr 90 0
10 * E Pup SB* 07 12 15.8091084326 -40 29 55.731520120   5.38 5.31     A1/2V:+ApSrEu 96 0
11 V* V827 Mon a2* 07 29 35.4522068599 -09 15 33.315319853   8.40 7.94     A6IIIpSr 63 0
12 HD 61468 * 07 38 22.5736029044 -27 52 07.623393473   9.86 9.83     ApEuCr(Sr) 22 0
13 * 53 Cam a2* 08 01 42.4313674994 +60 19 27.801603076   6.177 6.008     A3VpSrSiCrEu 386 0
14 HD 70331 * 08 19 17.3404884012 -48 04 09.935295721   8.79 8.85     B7/8II/III(pSi) 29 0
15 HD 75445 PM* 08 48 42.9335149812 -39 14 01.937632656   7.40 7.12     ApSrEu(Cr) 52 0
16 V* KU Hya a2* 09 22 50.8563427 -09 50 19.659199 6.86 6.75 6.53     ApEuCrSr 162 0
17 HD 93507 * 10 45 50.6285959632 -68 07 49.572337077   8.47 8.44     ApSiCrpec 38 0
18 V* KQ Vel a2* 10 55 01.0018015910 -42 15 04.062281118 5.78 6.03 6.11     Ap(SiCr) 124 0
19 V* AX CVn a2* 12 39 16.8607725899 +35 57 07.052954412   6.466 6.385     A0pSrCrEuKsn 164 0
20 HD 116114 PM* 13 21 46.3077068552 -18 44 31.541856988   7.34 7.02     F0VpSrCrEu 124 0
21 * 67 Mus SB* 13 25 50.3011564140 -70 37 38.091162600   5.626 5.651     ApHg(Mn) 117 0
22 V* LZ Hya a2* 13 41 19.8265550879 -28 46 59.792972629   10.41 9.92 9.63 9.659 ApSrEu(Cr) 43 0
23 V* FF Vir a2* 14 25 55.8784653958 +00 59 33.756463958 7.07 7.09 7.07     ApEuSrCr 165 0
24 V* HI Lib a2* 15 09 02.4050629548 -13 59 58.672652036   7.84 7.46     F2VpSrCrEu 122 0
25 * bet CrB a2* 15 27 49.7315305 +29 06 20.522375 4.08 3.97 3.68 3.50 3.45 F2VpSrCrEuSi 662 0
26 * 33 Lib a2* 15 29 34.7422042672 -17 26 27.375775287 7.22 7.07 6.69     F0VspEuGdSr 240 0
27 V* V373 Ser a2* 15 52 35.0678771388 -01 01 52.823842084   8.16 7.97     B9V 45 0
28 HD 144897 * 16 09 51.1809188214 -41 09 27.773840123   8.81 8.59     ApEuCr 47 0
29 V* V835 Ara a2* 16 44 11.4497196140 -48 39 18.115076026   10.40 9.91     A/F(pEu) 30 0
30 V* V970 Sco a2* 17 39 41.2403913936 -32 17 57.534800537   9.38 9.34     ~ 55 0
31 HD 165474 * 18 05 42.8402665933 +12 00 12.186136690   7.685 7.402     ~ 92 0
32 V* V694 CrA a2* 18 12 25.8347315452 -37 45 09.274292137   8.34 7.92     ApSrCrEu 108 0
33 HD 177765 * 19 07 09.7792915616 -26 19 54.507708452   9.60 9.15     ApSrEuCr 32 0
34 V* V3961 Sgr a2* 19 51 50.6105485243 -39 52 27.724256879 5.05 5.27 5.33     ApCr(Si) 174 0
35 V* V1291 Aql a2* 19 53 18.7357390150 -03 06 52.065320660   5.837 5.619     F0VpSrCrEu 263 0
36 V* V1372 Cyg a2* 20 13 36.3256530372 +53 39 33.549163874   7.334 7.333     A4p 123 0
37 HD 335238 * 20 50 43.6656489359 +29 48 12.040418354   9.30 9.26     A2 35 0
38 V* V2200 Cyg a2* 21 01 14.3202600937 +43 43 18.404151174   7.60 7.68     B9p 120 0
39 * gam Equ a2* 21 10 20.5001160337 +10 07 53.682085548 5.03 4.94 4.68 4.43 4.32 A9VpSrCrEu 522 0
40 V* BD Ind a2* 21 56 56.7032076410 -61 50 46.256627503   7.42 7.19     ApSrEuCr 54 0
41 V* GL Lac a2* 22 44 07.5047921489 +55 35 21.208257555   8.85 8.81     A0p 269 0
42 HD 216018 * 22 49 26.5144850245 -11 20 57.253626267   7.97 7.62     A(3)+F(m) 36 0

    Equat.    Gal    SGal    Ecl

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2021.06.21-15:32:44

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