2018A&A...619A..73L


C.D.S. - SIMBAD4 rel 1.7 - 2019.11.19CET05:19:14

2018A&A...619A..73L - Astronomy and Astrophysics, volume 619A, 73-73 (2018/11-1)

The Solar Twin Planet Search. The age-chromospheric activity relation.

LORENZO-OLIVEIRA D., FREITAS F.C., MELENDEZ J., BEDELL M., RAMIREZ I., BEAN J.L., ASPLUND M., SPINA L., DREIZLER S., ALVES-BRITO A. and CASAGRANDE L.

Abstract (from CDS):


Context. It is well known that the magnetic activity of solar-type stars decreases with age, but it is widely debated in the literature whether there is a smooth decline or if there is an early sharp drop until 1-2 Gyr that is followed by a relatively inactive constant phase.
Aims. We revisited the activity-age relation using time-series observations of a large sample of solar twins whose precise isochronal ages and other important physical parameters have been determined.
Methods. We measured the CaII H and K activity indices using ~=9000 HARPS spectra of 82 solar twins. In addition, the average solar activity was calculated through asteroids and Moon reflection spectra using the same instrumentation. Thus, we transformed our activity indices into the S Mount Wilson scale (SMW), recalibrated the Mount Wilson absolute flux and photospheric correction equations as a function of Teff, and then computed an improved bolometric flux normalized activity index log R'HK (Teff) for the entire sample.
Results. New relations between activity and the age of solar twins were derived by assessing the chromospheric age-dating limits using log R'HK (Teff). We measured an average solar activity of SMW=0.1712±0.0017 during solar magnetic cycles 23-24 covered by HARPS observations, and we also inferred an average of SMW=0.1694±0.0025 for cycles 10-24, anchored on a sunspot number correlation of S index versus. We also found a simple relation between the average and the dispersion of the activity levels of solar twins. This enabled us to predict the stellar variability effects on the age-activity diagram, and consequently, to estimate the chromospheric age uncertainties that are due to the same phenomena. The age-activity relation is still statistically significant up to ages around 6-7Gyr, in agreement with previous works using open clusters and field stars with precise ages.
Conclusions. Our research confirms that CaII H & K lines remain a useful chromospheric evolution tracer until stars reach ages of at least 6-7Gyr. We found evidence that for the most homogenous set of old stars, the chromospheric activity indices seem to continue to decrease after the solar age toward the end of the main sequence. Our results indicate that a significant part of the scatter observed in the age-activity relation of solar twins can be attributed to stellar cycle modulations effects. The Sun seems to have a normal activity level and variability for its age.

Abstract Copyright: © ESO 2018

Journal keyword(s): stars: solar-type - stars: evolution - stars: fundamental parameters - magnetic fields

VizieR on-line data: <Available at CDS (J/A+A/619/A73): table1.dat table2.dat>

Simbad objects: 36

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Number of rows : 36

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NGC 188 OpC 00 48 26 +85 15.3           ~ 796 0
2 HD 8291 PM* 01 22 18.7218217766 +03 30 47.255876676       8.3   G5V 35 0
3 HD 12264 PM* 02 00 05.3380960261 -13 32 46.000032697   8.64 7.98     G5V 47 0
4 HD 13357 ** 02 10 52.07912 +13 40 59.7887   8.35 7.65     G5IV 57 0
5 HD 14397 PM* 02 18 02.3350420032 -50 49 07.515951785   9.16 8.52     G3V 14 0
6 HD 19467 PM* 03 07 18.5750358835 -13 45 42.419198459   7.65 7.00 7.79 8.82 G3V 116 0
7 HD 20782 PM* 03 20 03.5777409770 -28 51 14.660409684   8.03 7.38     G1.5V 153 1
8 HD 25874 PM* 04 02 26.9852805917 -61 21 25.130544995   7.41 6.73     G2V 58 0
9 HD 26990 ** 04 16 16.5221579662 +07 09 33.777352427   8.14 7.51     G0V: 62 0
10 Cl Melotte 25 OpC 04 26 54.00 +15 52 00.0           ~ 2586 0
11 HD 42807 RS* 06 13 12.5027477683 +10 37 37.713412362   7.12   6.0   G5V 199 0
12 HD 45021 PM* 06 19 14.9364802274 -68 49 53.002288014   9.83 9.15     G5V 26 0
13 HD 71334 PM* 08 25 49.5157058164 -29 55 50.130492534   8.49 7.82     G2.5V 102 0
14 NGC 2682 OpC 08 51 18 +11 48.0           ~ 1990 0
15 HD 78429 PM* 09 06 38.8310540540 -43 29 31.117055567   7.93 7.33     G2V 96 0
16 HD 96116 * 11 04 13.6517787336 -57 45 54.473448673   9.34 8.69     G3V 47 0
17 HD 97037 PM* 11 10 13.3434298435 -07 23 21.845579922   7.42 6.81     G1V 79 0
18 HD 110537 PM* 12 42 59.3251300046 -04 02 57.596129000   8.51 7.83     G6/8V 64 0
19 HD 114174 ** 13 08 51.0231461021 +05 12 26.064930541   7.47   6.3   G3IV+D 136 0
20 HD 115031 PM* 13 15 20.5130831711 -55 20 29.725322411   8.98 8.34     G2/3V 39 0
21 HD 117126 SB* 13 28 18.7098973401 -00 50 24.697923338   8.08 7.44     G3/5V 76 0
22 HD 120690 SB* 13 51 20.3417568044 -24 23 25.843045584   7.133 6.43     G5Va 126 0
23 HD 129814 PM* 14 44 11.6934169422 +18 27 43.623343989       7.1   G5V 56 0
24 HD 131923 PM* 14 58 08.8006370909 -48 51 46.636950055   7.06 6.35     G4V 97 0
25 * psi Ser PM* 15 44 01.8189306784 +02 30 54.600773948       5.4   G2.5V 178 0
26 HD 145825 PM* 16 14 11.9123896278 -31 39 49.208930807   7.21 6.54     G3V 75 0
27 * 18 Sco PM* 16 15 37.2703721200 -08 22 09.981989277   6.15 5.50     G2Va 470 0
28 HD 150248 PM* 16 41 49.7946763722 -45 22 07.509805896   7.66 7.03     G3V+? 71 0
29 HD 153631 SB* 17 01 10.7539977843 -13 34 01.703128971   7.74 7.14     G0V 78 0
30 HD 163441 PM* 17 55 45.3496931214 +11 48 14.262712631   9.10 8.44     G5 38 0
31 * 16 Cyg ** 19 41 49.09 +50 31 31.6           ~ 112 0
32 HD 200565 PM* 21 04 05.6856103507 +03 58 50.286941779   9.05   8.0   G5V 56 0
33 V* NT Aqr BY* 22 06 05.3019536483 -05 21 29.385255187   8.26 7.58     G5V 75 0
34 HD 219057 * 23 13 09.8158069697 -30 26 59.297041339   10.222 9.625     G3V 34 0
35 HD 220507 PM* 23 24 42.1153597454 -52 42 06.761247344   8.28 7.58     G5V 76 0
36 HD 222582 PM* 23 41 51.5299950324 -05 59 08.731514665   8.34 7.69     G5V 194 2

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2019.11.19-05:19:14

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