2018A&A...619A...6O


C.D.S. - SIMBAD4 rel 1.7 - 2020.11.25CET07:25:33

2018A&A...619A...6O - Astronomy and Astrophysics, volume 619A, 6-6 (2018/11-1)

Estimating activity cycles with probabilistic methods. II. The Mount Wilson Ca H&K data.

OLSPERT N., LEHTINEN J.J., KAPYLA M.J., PELT J. and GRIGORIEVSKIY A.

Abstract (from CDS):


Context. Debate over the existence of branches in the stellar activity-rotation diagrams continues. Application of modern time series analysis tools to study the mean cycle periods in chromospheric activity index is lacking.
Aims. We develop such models, based on Gaussian processes (GPs), for one-dimensional time series and apply it to the extended Mount Wilson Ca H&K sample. Our main aim is to study how the previously commonly used assumption of strict harmonicity of the stellar cycles as well as handling of the linear trends affect the results.
Methods. We introduce three methods of different complexity, starting with Bayesian harmonic regression model, followed by GP regression models with periodic and quasi-periodic covariance functions. We also incorporate a linear trend as one of the components. We construct rotation to magnetic cycle period ratio-activity (RCRA) diagrams and apply a Gaussian mixture model to learn the optimal number of clusters explaining the data.
Results. We confirm the existence of two populations in the RCRA diagram; this finding is robust with all three methods used. We find only one significant trend in the inactive population, namely that the cycle periods get shorter with increasing rotation, leading to a positive slope in the RCRA diagram. This is in contrast with earlier studies, that postulate the existence of trends of different types in both of the populations. Our data is consistent with only two activity branches (inactive, transitional) instead of three (inactive, active, transitional) such that the active branch merges together with the transitional one. The retrieved stellar cycles are uniformly distributed over the RHK' activity index, indicating that the operation of stellar large-scale dynamos carries smoothly over the Vaughan-Preston gap. At around the solar activity index, however, indications of a disruption in the cyclic dynamo action are seen.
Conclusions. Our study shows that stellar cycle estimates from time series the length of which is short in comparison to the searched cycle itself depend significantly on the model applied. Such model-dependent aspects include the improper treatment of linear trends, while the assumption of strict harmonicity can result in the appearance of double cyclicities that seem more likely to be explained by the quasi-periodicity of the cycles. In the case of quasi-periodic GP models, which we regard the most physically motivated ones, only 15 stars were found with statistically significant cycles against red noise model. The periodicities found have to, therefore, be regarded as suggestive.

Abstract Copyright: © ESO 2018

Journal keyword(s): stars: activity - methods: statistical

Simbad objects: 78

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Number of rows : 78

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 * 85 Peg SB* 00 02 10.3411392575 +27 04 54.476788744 6.47 6.42 5.75 5.16 4.73 G5VbFe-2 527 0
2 * 9 Cet BY* 00 22 51.7883318927 -12 12 33.972374893 7.29 7.05 6.39     G2.5V 454 0
3 HD 2454 PM* 00 28 20.0441170647 +10 11 23.308682092   6.47   5.8   F5VSr 163 0
4 * 14 Cet PM* 00 35 32.8335385951 -00 30 20.198144650   6.368 5.936     F5V 119 0
5 * 54 Psc PM* 00 39 21.8055114029 +21 15 01.716052732 7.29 6.71 5.88 5.21 4.82 K0.5V 532 1
6 HD 4628 PM* 00 48 22.9763438736 +05 16 50.209562003 7.22 6.64 5.74 4.99 4.52 K2.5V 452 0
7 * chi And SB* 01 39 20.9882801730 +44 23 10.199584793   5.886 5.008     G8III 79 0
8 * 107 Psc PM* 01 42 29.7634932653 +20 16 06.660242064 6.57 6.08 5.24 4.55 4.12 K1V 510 0
9 HD 10780 BY* 01 47 44.8336250528 +63 51 09.007331430 6.84 6.44 5.63 4.99 4.60 K0V 318 0
10 HD 16160 PM* 02 36 04.9023844802 +06 53 12.431588708   6.81   5.2   K3V 488 1
11 HD 16673 SB* 02 40 12.4221262303 -09 27 10.336039665   6.294 5.790     F8VFe-0.4 218 0
12 * rho Ari PM* 02 56 26.1717266513 +18 01 23.665188613   6.06   5.3   F6V 148 0
13 * kap01 Cet BY* 03 19 21.6963205 +03 22 12.715139 5.71 5.52 4.85 4.27 3.91 G5V 827 0
14 * eps Eri BY* 03 32 55.8449634 -09 27 29.731165 5.19 4.61 3.73 3.00 2.54 K2V 1720 1
15 * omi02 Eri Er* 04 15 16.3197260 -07 39 10.338087 5.69 5.25 4.43 3.74 3.29 K0V 748 0
16 HD 26913 BY* 04 15 25.7871510436 +06 11 58.749263209 7.790 7.580 6.920 6.554 6.195 G8V 200 0
17 HD 26923 Ro* 04 15 28.8004956278 +06 11 12.699896698 6.910 6.860   5.9   G0IV 188 0
18 HD 27022 * 04 20 40.3249776693 +65 08 25.591905111 6.55 6.08 5.27 4.63 4.20 G4III 147 0
19 * 3 Cam SB* 04 39 54.6799466629 +53 04 46.317734033   6.158 5.073     G9III 92 0
20 * 63 Eri SB* 04 59 50.4609687587 -10 15 47.820334404   6.180 5.390     G4IV-V+DA 99 1
21 HD 32147 PM* 05 00 48.9991346145 -05 45 13.220341956 8.27 7.27 6.21 5.36 4.87 K3+V 418 1
22 HD 33608 PM* 05 11 19.1762022726 -02 29 26.814981908   6.346 5.892     F5V 121 0
23 HD 37394 BY* 05 41 20.3357283721 +53 28 51.810629854 7.58 7.07 6.23 5.54 5.11 K1 299 0
24 * 57 Gem PM* 07 23 28.5112255926 +25 03 01.913058212   5.933 5.022     G8III 89 0
25 * ups Gem PM* 07 35 55.3506173748 +26 53 44.711452380 7.54 5.60 4.06 2.82 1.91 M0III 193 0
26 * 19 Pup ** 08 11 16.3058502 -12 55 37.195175 6.44 5.68 4.72 3.99 3.51 G8.5IIIb 76 0
27 * 5 LMi PM* 08 50 32.2225492041 +33 17 06.200101841   6.738 6.210     F7Vs 145 0
28 HD 76151 PM* 08 54 17.9469808897 -05 26 04.046487788 6.89 6.67 6.00     G2V 479 0
29 * 61 Cnc Ro* 08 57 58.6675878979 +30 14 01.771959638   6.692 6.239     F4V 67 0
30 HD 78366 PM* 09 08 51.0705427688 +33 52 55.988119240   6.53   5.6   G0IV-V 219 0
31 HD 81809 SB* 09 27 46.77993 -06 04 16.2822   6.02 5.40     G1.5IV-V 277 0
32 V* LQ Hya BY* 09 32 25.5684079124 -11 11 04.687410738 9.316 8.761 7.891 7.288 6.815 K1Vp 405 0
33 HD 82443 BY* 09 32 43.7594363452 +26 59 18.708212270   7.78   6.6   G9V(k) 222 1
34 * 10 LMi RS* 09 34 13.3814384371 +36 23 51.216307794   5.47 4.60     G7.5IIIb 143 0
35 * 11 LMi RS* 09 35 39.5018053382 +35 48 36.484070234 6.560 6.110 5.340 4.79 4.42 G8Va 347 0
36 * ups01 Hya * 09 51 28.6938376 -14 50 47.771030 5.68 5.03 4.11 3.42 2.95 G7III 145 0
37 HD 88373 * 10 11 16.7876347101 -09 24 07.144903372   9.18 8.67     F5V 8 0
38 HD 88737 PM* 10 14 29.7522465320 +21 10 04.975693602       5.7   F9V 119 0
39 * 40 Leo dS* 10 19 44.1668778 +19 28 15.294314   5.24   4.5   F6IV-V 249 0
40 * 88 Leo ** 11 31 44.9446108040 +14 21 52.213131158   6.77   5.9   F9.5V 174 0
41 * 61 UMa PM* 11 41 03.0159358291 +34 12 05.882438337 6.31 6.08 5.34 4.73 4.38 G8V 570 0
42 HD 103095 PM* 11 52 58.7683801554 +37 43 07.240082865 7.38 7.20 6.45 5.80 5.35 K1V_Fe-1.5 750 1
43 HD 111456 ** 12 48 39.4470003426 +60 19 11.037876361   6.299 5.831     F6V 193 1
44 * bet Com PM* 13 11 52.3937856 +27 52 41.453553 4.92 4.84 4.25 3.77 3.47 F9.5V 850 0
45 HD 115043 PM* 13 13 37.0081498408 +56 42 29.762950141   7.423 6.813     G1Va 240 0
46 * e Vir PM* 13 16 46.5161591991 +09 25 26.967205938   5.81   4.8   G0V 507 1
47 HD 115404 PM* 13 16 51.0517063595 +17 01 01.840304856   7.69 6.66     K2V 257 0
48 * tau Boo Ro* 13 47 15.74340 +17 27 24.8552 5.02 4.98 4.49 4.09 3.85 F7IV-V 890 1
49 * alf Boo RG* 14 15 39.67207 +19 10 56.6730 2.46 1.18 -0.05 -1.03 -1.68 K1.5IIIFe-0.5 2150 0
50 HD 126053 PM* 14 23 15.2847534665 +01 14 29.641784590 6.98 6.90 6.27 5.71 5.39 G1.5V 364 0
51 * ksi Boo A PM* 14 51 23.3876853015 +19 06 01.641924918   5.40 4.675     G7Ve 501 0
52 * 18 Sco PM* 16 15 37.2703721200 -08 22 09.981989277   6.15 5.50     G2Va 493 0
53 * 12 Oph BY* 16 36 21.4492997704 -02 19 28.512485729 7.00 6.55 5.77 5.13 4.74 K1V 453 0
54 HD 152391 Ro* 16 52 58.8025427362 -00 01 35.116299669   7.40 6.64     G8.5Vk: 339 0
55 V* V2213 Oph BY* 17 05 16.8186294192 +00 42 09.217571716   6.59   5.6   F8.5IV-V 318 0
56 * 36 Oph A PM* 17 15 20.7837627960 -26 36 06.120125290   5.93 5.08     K2V 248 0
57 * 36 Oph B PM* 17 15 20.9846233161 -26 36 10.159381821   5.88 5.03     K1V 227 0
58 V* V2215 Oph RS* 17 16 13.3627374963 -26 32 46.133091527   7.50 6.34   4.8 K5V 281 0
59 HD 157856 PM* 17 25 57.8752864191 -01 39 06.408239689   6.872 6.440     F5V 91 0
60 HD 160346 SB* 17 39 16.9163262 +03 33 18.875718   7.496 6.525 5.9   K3-V 271 0
61 * 84 Her PM* 17 43 21.5646072179 +24 19 40.157353689   6.394 5.729     G2IIIb 136 0
62 * 70 Oph A SB* 18 05 27.370543 +02 29 59.31669       3.6   K0V 207 0
63 * 70 Oph B PM* 18 05 27.4622283249 +02 29 56.223591080   7.26 6.07 5.6   K4V 103 0
64 HD 166620 PM* 18 09 37.4162810870 +38 27 27.995921559 7.86 7.27 6.40 5.63 5.14 K2V 395 0
65 HD 176051 SB* 18 57 01.60985 +32 54 04.5723 5.85 5.82   4.9   F9V+K1V 239 1
66 HD 182101 PM* 19 22 48.3509752008 +09 54 47.339080185   6.789 6.346     F6V 112 0
67 * sig Dra PM* 19 32 21.5902990 +69 39 40.234737 5.860 5.460 4.680 4.04 3.63 K0V 586 0
68 * omi Aql PM* 19 51 01.6437560393 +10 24 56.595177367   5.66   4.8   F8V 425 0
69 * bet Aql PM* 19 55 18.7925630 +06 24 24.342501 5.040 4.560 3.710 3.05 2.56 G8IV 516 0
70 HD 190007 BY* 20 02 47.0455912903 +03 19 34.264805769   8.60   6.8   K5V 203 0
71 * 15 Sge PM* 20 04 06.2209062328 +17 04 12.677429047   6.390 5.788 5.4   G0V 341 0
72 HD 194012 PM* 20 22 52.3693290617 +14 33 03.946961940   6.635 6.152     F7V 102 1
73 * 61 Cyg A BY* 21 06 53.9396100677 +38 44 57.897024357 7.50 6.39 5.21 4.19 3.54 K5V 952 0
74 * 61 Cyg B Er* 21 06 55.2640651855 +38 44 31.362140913 8.63 7.40 6.03 4.86 3.55 K7V 672 1
75 V* HN Peg BY* 21 44 31.3299733695 +14 46 18.982331039       6.16   G0V+ 455 0
76 * pi. Cep SB* 23 07 53.85377 +75 23 14.9951 5.67 5.21 4.41     G2III 171 0
77 * 94 Aqr B PM* 23 19 06.5608518922 -13 27 18.903718042         8.37 K2 70 1
78 * 94 Aqr SB* 23 19 06.7256972451 -13 27 31.614580771   5.95 5.18     G8.5IV 193 0

    Equat.    Gal    SGal    Ecl

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2020.11.25-07:25:33

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