2009A&A...499L...9P


Query : 2009A&A...499L...9P

2009A&A...499L...9P - Astronomy and Astrophysics, volume 499, L9-12 (2009/5-3)

An investigation of chromospheric activity spanning the Vaughan-Preston gap: impact on stellar ages.

PACE G., MELENDEZ J., PASQUINI L., CARRARO G., DANZIGER J., FRANCOIS P., MATTEUCCI F. and SANTOS N.C.

Abstract (from CDS):

Chromospheric activity is widely used as an age indicator for solar-type stars based on the early evidence that there is a smooth evolution from young and active to old and inactive stars. However, this transition may require modification as chromospheric activity is not a viable age indicator for stars older than 1 Gyr. We analysed chromospheric activity in five solar-type stars in two open clusters, in order to study how chromospheric activity evolves with time. We took UVES high-resolution, high S/N ratio spectra of 3 stars in IC 4756 and 2 in NGC 5822, which were combined with a previously studied data-set and reanalysed here. The emission core of the deep, photospheric CaII K line was used as a probe of the chromospheric activity. All of the 5 stars in the new sample, including those in the 1.2Gyr-old NGC 5822, have activity levels comparable to those of Hyades and Praesepe. A likely interpretation of our data is that solar-type-star chromospheric activity, from the age of the Hyades until that of the Sun, does not evolve smoothly. Stars change from active to inactive, crossing the activity range corresponding to the Vaughan-Preston gap, on a time-scale that might be as short as 200 Myr. Evolution before and after such a transition is much less significant than cyclical and long-term variations. We show that data presented in the literature to support a correlation between age and activity could be also interpreted differently in the light of our results. Suggestions have been published that relevant stellar structures and/or dynamos are different for active and inactive stars. These provide a natural explanation for the observations presented here. More observations are required in order to strengthen our results, especially a long-term follow up of our two targets in the 1.2-Gyr old cluster NGC 5822.

Abstract Copyright:

Journal keyword(s): stars: chromospheres

Simbad objects: 48

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Number of rows : 48
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 NGC 752 OpC 01 56 54 +37 47.6           ~ 608 0
2 HD 20430 PM* 03 17 26.3862805584 +07 39 20.919521880   7.958 7.373 7.050 6.739 F8 130 0
3 HD 20439 PM* 03 17 32.7800971992 +07 41 24.556610724   8.376 7.747 7.402 7.085 ~ 134 1
4 HD 25825 PM* 04 06 16.1277225936 +15 41 53.233746900   8.416 7.811 7.484 7.169 G0V 182 0
5 HD 26756 PM* 04 14 25.6501896480 +14 37 30.115628868   9.125 8.419 8.039 7.682 G5V 198 0
6 V* V1309 Tau BY* 04 14 27.2546195976 +12 26 07.133100324   8.682 8.030 7.673 7.341 G0 160 0
7 HD 26736 BY* 04 14 32.3145372576 +23 34 29.798635044   8.711 8.047 7.691 7.356 G5V 207 0
8 HD 27406 BY* 04 20 12.9666179232 +19 14 00.518450172   8.016 7.444 7.131 6.826 F9V+ 187 0
9 HD 27835 PM* 04 24 12.7838536080 +16 22 44.148778356   8.808 8.203 7.870 7.560 G0V 111 0
10 HD 27859 BY* 04 24 28.3269703416 +16 53 10.202918748   8.382 7.790     G2V 215 0
11 V* V993 Tau BY* 04 27 35.8912011816 +15 35 21.090336828   7.949 7.404 7.102 6.805 ~ 222 0
12 HD 28237 PM* 04 27 46.0745928288 +11 44 11.108386212   8.066 7.482     F8 145 0
13 HD 28344 BY* 04 28 48.2984108040 +17 17 07.685984400 8.57 8.456 7.837 7.498 7.180 G2V 272 0
14 Cl Melotte 25 OpC 04 29 47 +16 56.9           ~ 2928 0
15 HD 28635 SB* 04 31 29.3493834048 +13 54 12.334345092   8.300 7.746 7.445 7.147 F9V 142 0
16 HD 28992 BY* 04 34 35.3100676992 +15 30 16.642906992   8.530 7.898 7.556 7.226 ~ 199 0
17 HD 30589 PM* 04 49 32.1249486336 +15 53 19.474899432   8.324 7.739 7.412 7.111 F8 124 0
18 Cl* NGC 2632 S 25 Ro* 08 37 46.6100294766 +19 26 18.046945074   11.243 10.635     F9V 52 0
19 K2-100 Ro* 08 38 24.3002838928 +20 06 21.828057218   11.085 10.521     G0V 86 0
20 Cl* NGC 2632 S 83 Ro* 08 39 45.7489350539 +19 22 01.145101156   11.257 10.640     G0 67 0
21 NGC 2632 OpC 08 40 13 +19 37.3           ~ 1449 0
22 Cl* NGC 2632 S 138 Ro* 08 40 42.4813583883 +19 33 57.623817270   12.063 11.331     G4V 60 0
23 Cl* NGC 2632 S 155 SB* 08 41 10.3080648125 +19 49 07.006491032   12.268 11.495     G6.6 57 0
24 BD+20 2181 Ro* 08 41 25.8429243867 +19 56 36.848107538   11.342 10.687     G0V 62 0
25 BD+20 2184 Ro* 08 41 43.8160475073 +20 13 36.752729096   10.988 10.431     F7 77 1
26 Cl* NGC 2682 ES I-46 * 08 50 53.3445488184 +11 43 40.066038660 15.318 15.06 14.448   13.569 G0V 47 0
27 NGC 2682 OpC 08 51 23 +11 48.8           ~ 2233 0
28 NGC 2682 159 * 08 51 27.8885213448 +11 55 40.949794380 14.598 13.94 13.320   12.625 G1IV 45 0
29 Cl* NGC 2682 ES III-9 * 08 51 27.9474345912 +11 50 11.918733972 15.180 15.08 14.491   13.669 G4V 40 0
30 Cl* NGC 2682 ES III-13 * 08 51 29.9638737600 +11 51 09.062555832 14.821 14.72 14.191 13.773 13.398 G2V 40 0
31 NGC 2682 178 * 08 51 31.9171704744 +11 51 16.663779036 14.694 14.63 14.030 13.704 13.304 G0V 34 0
32 Cl* NGC 2682 ES II-7 * 08 51 36.0753333984 +11 47 47.048568468 15.268 15.14 14.486   13.745 G1V 42 0
33 NGC 3680 70 * 11 25 03.4757162376 -43 17 26.302286508   15.220 14.651     ~ 23 0
34 NGC 3680 OpC 11 25 34 -43 14.4   8.40 7.6     ~ 309 0
35 NGC 3680 60 * 11 26 20.7065904912 -43 13 07.467128544   14.99 14.36     ~ 28 0
36 NGC 5822 OpC 15 04 12 -54 22.0           ~ 197 0
37 Cl* NGC 5822 TA 11014 * 15 04 35.3020493712 -54 17 37.545141408 16.334 15.182 14.423 14.51   ~ 8 0
38 Cl* NGC 5822 TA 11003 * 15 04 54.2483851032 -54 15 48.387190356   15.43 14.66 14.42 13.90 ~ 7 0
39 Cl* IC 4651 MEI 6081 * 17 24 31.8192107640 -49 59 08.591260884           ~ 14 0
40 Cl* IC 4651 AMC 4226 * 17 24 43.4557289976 -50 01 01.275456828           ~ 17 0
41 IC 4651 17 * 17 24 48.0970940376 -49 55 47.356824144   15.250 14.545     ~ 13 0
42 IC 4651 OpC 17 24 51 -49 55.0           ~ 339 0
43 IC 4651 65 * 17 24 59.9718574488 -49 53 07.834464996       14.41   ~ 16 0
44 IC 4651 43 * 17 25 14.2401503784 -49 56 43.669147992   14.89 14.193     ~ 22 0
45 IC 4756 368 * 18 37 37.6956654408 +05 31 00.419299212 14.60 14.23 13.38     ~ 5 0
46 Cl* IC 4756 HER 165 * 18 38 18.8409758256 +05 31 02.863451964   14.31 13.591 13.110 12.650 G5V 8 0
47 IC 4756 OpC 18 38 31.2 +05 29 24           ~ 226 0
48 IC 4756 425 * 18 38 47.2849416456 +05 16 24.979311768 14.61 14.24 13.48 13.70   G2V 9 0

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2023.01.27-11:21:29

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