2007A&A...475..991F


Query : 2007A&A...475..991F

2007A&A...475..991F - Astronomy and Astrophysics, volume 475, 991-1002 (2007/12-1)

A search for solar-like oscillations in K giants in the globular cluster M4.

FRANDSEN S., BRUNTT H., GRUNDAHL F., KOPACKI G., KJELDSEN H., ARENTOFT T., STELLO D., BEDDING T.R., JACOB A.P., GILLILAND R.L., EDMONDS P.D., MICHEL E. and MATTHIESEN J.

Abstract (from CDS):

To expand the range in the colour-magnitude diagram where asteroseismology can be applied, we organized a photometry campaign to find evidence for solar-like oscillations in giant stars in the globular cluster M4. The aim was to detect the comb-like p-mode structure characteristic for solar-like oscillations in the amplitude spectra. The 24 main target stars are in the region of the bump stars and have luminosities in the range 50-140L. We collected 6160 CCD frames and light curves for about 14000 stars were extracted. The frames consist of exposures in the Johnson B, V and R bands and were obtained at three different telescopes. Three different software packages were applied to obtain the lowest possible photometric noise level. The resulting light curves have been analysed for signatures of oscillations using a variety of methods. We obtain high quality light curves for the K giants, but no clear oscillation signal is detected. This is a surprise as the noise levels achieved in the amplitude spectra should permit oscillations to be seen at the levels predicted by extrapolating from stars at lower luminosities. In particular, when we search for the signature of oscillations in a large number of stars we might expect to see common features in the power spectra, but even here we fall short of having clear evidence of oscillations. High precision differential photometry is possible even in very crowded regions like the core of M4. Solar-like oscillations are probably present in K giants, but the amplitudes are lower than classical scaling laws predict. The reasons may be that the lifetime of the modes are short or the driving mechanism is relatively inefficient in giant stars.

Abstract Copyright:

Journal keyword(s): stars: oscillations - stars: activity - techniques: photometric - methods: observational - stars: evolution

Nomenclature: Table 2, col(1): Cl* NGC 6121 FBG NNN N=24 among (Nos 66-293), Table 2, col(2): Cl* NGC 6121 S NNNN N=13 among (Nos 243-1753).

Simbad objects: 31

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Number of rows : 31
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 104 GlC 00 24 05.359 -72 04 53.20   5.78 4.09     ~ 3771 0
2 NGC 2682 OpC 08 51 23 +11 48.8           ~ 2220 0
3 * ksi Hya ** 11 33 00.1150559 -31 51 27.443449 5.17 4.47 3.54 2.84 2.36 G7IIIb 247 0
4 * eps Oph PM* 16 18 19.2897431 -04 41 33.034466 4.95 4.21 3.23 2.54 2.05 G9.5IIIbFe-0.5 229 0
5 NGC 6121 207 RG* 16 23 20.0868788832 -26 32 41.554776336 15.46 14.726 13.492   11.984 ~ 10 0
6 2MASS J16232169-2626468 RG* 16 23 21.6956365512 -26 26 46.944146328 15.61 14.821 13.565   12.031 ~ 12 0
7 Cl* NGC 6121 ALC 258 RG* 16 23 22.5271470048 -26 29 42.277971840 13.64 15.254 14.046     ~ 5 0
8 Cl* NGC 6121 S 1753 RG* 16 23 23.0205576120 -26 30 33.673417092 15.48 14.661 13.459   11.906 ~ 8 0
9 2MASS J16232465-2631114 RG* 16 23 24.6537603408 -26 31 11.501504652 15.65 14.893 13.630   12.089 ~ 11 0
10 Cl* NGC 6121 ALC 427 RG* 16 23 26.1195469824 -26 30 40.310763912 15.81 15.226 14.038 13.794 12.56 ~ 5 0
11 NGC 6121 89 RG* 16 23 27.0069390312 -26 30 44.470825020 15.38 14.555 13.291   11.764 ~ 14 0
12 NGC 6121 90 RG* 16 23 27.4228316424 -26 30 59.620969476 15.30 14.39 13.073   11.427 ~ 15 0
13 2MASS J16233236-2629222 RG* 16 23 32.3636738232 -26 29 22.281240948 15.66 14.992 13.880   12.368 ~ 12 0
14 2MASS J16233236-2626205 RG* 16 23 32.3708260704 -26 26 20.601330540 15.23 14.364 13.061   11.489 ~ 15 0
15 M 4 GlC 16 23 35.22 -26 31 32.7           ~ 1779 0
16 NGC 6121 72 RG* 16 23 41.7586076760 -26 29 46.773230316 15.68 15.02 13.807   12.284 ~ 11 0
17 2MASS J16234225-2632061 RG* 16 23 42.2604992832 -26 32 06.243594216 15.79 15.12 13.927   12.414 ~ 10 0
18 2MASS J16234260-2633174 RG* 16 23 42.6021374304 -26 33 17.495740584 15.53 14.961 13.793   12.23 ~ 7 0
19 Cl* NGC 6121 ALC 318 RG* 16 23 43.0923509424 -26 28 07.468793256 15.50 14.75 13.548   12.047 ~ 13 0
20 Cl* NGC 6121 SAW V60 RG* 16 23 45.2128635960 -26 33 56.900805768 15.54 14.82 13.56 12.79 12.02 ~ 17 0
21 2MASS J16234764-2631042 RG* 16 23 47.6473765008 -26 31 04.240658316 15.45 14.704 13.484   12.007 ~ 11 0
22 NGC 6121 78 RG* 16 23 47.8825228152 -26 29 48.285234744 15.50 14.783 13.575   12.106 ~ 18 0
23 2MASS J16234798-2632428 RG* 16 23 47.9909896704 -26 32 42.908457516 15.64 15.00 13.789   12.288 ~ 10 0
24 2MASS J16234899-2629191 RG* 16 23 48.992 -26 29 19.17 15.48 14.94 13.798   12.311 ~ 9 0
25 NGC 6121 478 RG* 16 23 50.1548234376 -26 32 19.496693760 15.46 14.70 13.440   11.902 ~ 11 0
26 NGC 6121 431 RG* 16 23 50.2613060976 -26 29 25.894920300 15.33 14.610 13.408   11.957 ~ 10 0
27 NGC 6121 385 RG* 16 23 53.0053327056 -26 28 06.600361584 15.43 14.744 13.520   12.033 ~ 12 0
28 Cl* NGC 6121 S 364 * 16 23 53.65 -26 33 55.0   14.193 12.93     ~ 1 0
29 2MASS J16235482-2631199 RG* 16 23 54.8223806664 -26 31 19.949551500 15.01 14.34 13.14   11.59 ~ 8 0
30 * eta Ser PM* 18 21 18.6005560 -02 53 55.776595 4.84 4.19 3.25 2.55 2.05 K0III-IV 365 0
31 * nu. Ind ** 22 24 36.8853892493 -72 15 19.488237466   5.94 5.29     G9VFe-3.1CH-1.5 266 0

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2022.12.09-19:32:29

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