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


Query : 2018A&A...619A..73L

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 - 2022
#notes
1 NGC 188 OpC 00 47 12 +85 14.6           ~ 869 0
2 HD 8291 PM* 01 22 18.7201978824 +03 30 47.265398424   9.345 9.109 8.910   G5V 46 0
3 HD 12264 PM* 02 00 05.3379490800 -13 32 46.000535316   8.64 7.98     G5V 57 0
4 HD 13357A PM* 02 10 52.0805988576 +13 40 59.802335688   8.88 8.20 8.75   dG4 74 0
5 HD 14397 PM* 02 18 02.3348918448 -50 49 07.516941132   9.16 8.52     G3V 18 0
6 HD 19467 PM* 03 07 18.5750514360 -13 45 42.417982152   7.65 7.00 7.79 8.82 G3V 146 0
7 HD 20782 PM* 03 20 03.5777546706 -28 51 14.660358176   8.03 7.38     G1.5V 183 1
8 HD 25874 PM* 04 02 26.9793730553 -61 21 25.167093153   7.41 6.73     G2V 71 0
9 HD 26990 ** 04 16 16.5072970248 +07 09 33.968089296   8.14 7.51     G0V: 74 0
10 Cl Melotte 25 OpC 04 29 47 +16 56.9           ~ 2860 0
11 HD 42807 RS* 06 13 12.5028624208 +10 37 37.712484445   7.12   6.0   G5V 220 0
12 HD 45021 PM* 06 19 14.9358688152 -68 49 53.001022908   9.83 9.15     G5V 34 0
13 HD 71334 PM* 08 25 49.5155726353 -29 55 50.133816869   8.49 7.82     G2.5V 118 0
14 NGC 2682 OpC 08 51 23 +11 48.8           ~ 2191 0
15 HD 78429 PM* 09 06 38.8310026968 -43 29 31.119230904   7.93 7.33     G2V 114 0
16 HD 96116 * 11 04 13.6519319736 -57 45 54.477392472   9.34 8.69     G3V 59 0
17 HD 97037 PM* 11 10 13.3432488456 -07 23 21.847546068   7.42 6.81     G1V 94 0
18 HD 110537 PM* 12 42 59.3250781968 -04 02 57.597087624   8.51 7.83     G6/8V 80 0
19 HD 114174 ** 13 08 51.0229724195 +05 12 26.065953963   7.47   6.3   G3IV+D 160 0
20 HD 115031 PM* 13 15 20.5133822208 -55 20 29.728277268   8.98 8.34     G2/3V 49 0
21 HD 117126 SB* 13 28 18.7088282396 -00 50 24.689386051   8.08 7.44     G3/5V 88 0
22 HD 120690 SB* 13 51 20.3417568044 -24 23 25.843045584   7.133 6.43     G5Va 137 0
23 HD 129814 PM* 14 44 11.6930943288 +18 27 43.624117548       7.1   G5V 70 0
24 HD 131923 PM* 14 58 08.7944361399 -48 51 46.620867845   7.048 6.347     G4V 110 0
25 * psi Ser PM* 15 44 01.8185683752 +02 30 54.600593940       5.4   G2.5V 205 0
26 HD 145825 PM* 16 14 11.9148076848 -31 39 49.154897988   7.21 6.54     G3V 86 0
27 * 18 Sco PM* 16 15 37.2702755653 -08 22 09.982125430   6.15 5.50     G2Va 545 0
28 HD 150248 PM* 16 41 49.7935085784 -45 22 07.512832956   7.66 7.03     G3V+? 82 0
29 HD 153631 SB* 17 01 10.7567400948 -13 34 01.607438699   7.74 7.14     G0V 91 0
30 HD 163441 PM* 17 55 45.3501544704 +11 48 14.264934084   9.10 8.44     G5 48 0
31 * 16 Cyg ** 19 41 49.09 +50 31 31.6           ~ 133 0
32 HD 200565 PM* 21 04 05.6838067968 +03 58 50.384739504   9.05   8.0   G5V 65 0
33 V* NT Aqr BY* 22 06 05.3027674728 -05 21 29.390445108   8.26 7.58     G5V 88 0
34 HD 219057 * 23 13 09.8157352392 -30 26 59.297952192   10.222 9.625     G3V 48 0
35 HD 220507 PM* 23 24 42.1153260048 -52 42 06.759585936   8.28 7.58     G5V 92 0
36 HD 222582 PM* 23 41 51.5300932008 -05 59 08.729137104   8.34 7.69     G5V 217 2

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2022.08.09-21:44:05

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