1998A&A...337..372R

Query : 1998A&A...337..372R

1998A&A...337..372R - Astronomy and Astrophysics, volume 337372-378 (1998/9-2)

ROSAT HRI observations of the intermediate-age open cluster IC 4756.

RANDICH S., SINGH K.P., SIMON T., DRAKE S.A. and SCHMITT J.H.M.M.

Abstract (from CDS):

We have obtained an 88 kilosecond ROSAT HRI exposure of the intermediate-age open cluster IC 4756 with the purpose of detecting stars in the high luminosity tail (logLX≥1029erg/s) of its X-ray luminosity distribution. However, only 1 cluster member (HSS 201) out of the 60 members inside the central high-sensitivity region of the HRI field of view (FOV) was detected. This star has spectral type A8, suggesting a close binary system with a low mass X-ray emitting companion. We compare the distribution of upper limits for F and G-type dwarfs in IC 4756 with the X-ray distribution functions of the similarly aged Hyades and Praesepe clusters. The results of this statistical analysis are inconclusive for G-type stars, but suggest that at least F-type stars in IC 4756 are not as X-ray luminous as their Hyades counterparts, thus indicating intrinsic differences between the two clusters. Finally, our data indicate a deficit of very active binaries with respect to both Hyades and Praesepe, and older open clusters.

Abstract Copyright: ∼

Journal keyword(s): stars: activity - X-rays: stars - open clusters and associations: individual: IC 4756

Nomenclature: Table 1: [RSS98] NN (Nos 1-10).

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 - 2026 		#notes
1 NGC 752 OpC 01 56 53.7 +37 45 06           ~ 712 0
2 Cl Melotte 25 OpC 04 30 27.4 +16 46 43           ~ 3309 0
3 NGC 2632 OpC 08 39 58.4 +19 36 33           ~ 1733 0
4 NGC 2682 OpC 08 51 23.5 +11 48 54           ~ 2528 0
5 IC 4651 OpC 17 24 48.5 -49 55 23           ~ 374 0
6 BD+05 3839 * 18 37 34.2155606904 +05 28 33.420811116 10.30 10.50 9.46     ~ 48 0
7 BD+05 3844 * 18 37 40.3865283336 +05 29 44.589310008 10.30 10.45 9.98 9.8   F2V 15 0
8 BD+05 3845 * 18 37 48.6238945848 +05 19 33.682434600 10.33 10.47 10.08     F2 14 0
9 IC 4756 66 * 18 37 57.4740109296 +05 38 23.683903692 10.47 10.56 10.13     A5 25 0
10 BD+05 3849 * 18 38 00.5494915752 +05 35 19.363448364 10.30 10.41 9.90 9.6   A5IV 24 0
11 BD+05 3850 SB* 18 38 05.1613660152 +05 24 33.720370164 10.02 10.29 9.24     K0 32 0
12 IC 4756 70 * 18 38 06.6298744344 +05 19 50.152074852 10.81 11.04 10.63     F0 21 0
13 BD+05 3851 * 18 38 08.1275109648 +05 31 51.335043204 10.70 10.84 10.40     A2 21 0
14 BD+05 3852 * 18 38 08.7697311960 +05 20 55.465697904 9.92 10.21 9.70     A5: 24 0
15 IC 4756 73 * 18 38 08.9143986384 +05 27 47.860346808 10.78 10.97 10.56     A0 17 0
16 BD+05 3856 * 18 38 15.3943794048 +05 39 39.171470652 10.35 10.51 9.98 9.88   F0 10 0
17 BD+05 3857 SB* 18 38 17.5838381448 +05 38 16.985007132 10.22 10.56 9.53     G5 29 0
18 Cl* IC 4756 HER 165 * 18 38 18.8409758256 +05 31 02.863451964   14.31 13.591 13.110 12.650 G5V 8 0
19 USNO-A2.0 0900-13330140 X 18 38 20.14 +05 24 58.0           ~ 2 0
20 BD+05 3858 * 18 38 20.7633328128 +05 26 02.301879660 10.05 10.46 9.46     ~ 37 0
21 [RSS98] 2 X 18 38 31.29 +05 23 09.1           ~ 1 0
22 [BPJ2000] IC 4756 2 X 18 38 31.96 +05 31 52.1           ~ 2 0
23 BD+05 3863 * 18 38 35.8815511920 +05 34 48.652713012 10.25 10.32 9.94     A8 18 0
24 [BPJ2000] IC 4756 4 X 18 38 37.00 +05 35 45.6           ~ 2 0
25 [BPJ2000] IC 4756 5 X 18 38 37.89 +05 33 59.1           ~ 2 0
26 IC 4756 OpC 18 38 39.0 +05 26 14           ~ 274 0
27 IC 4756 94 * 18 38 39.2811151248 +05 17 05.442928332 10.74 10.94 10.55     F6 8 0
28 BD+05 3866 * 18 38 39.8231728200 +05 41 04.069574556 10.88 10.95 10.62     A3 19 0
29 BD+05 3869 * 18 38 43.7448704928 +05 17 55.911292620 9.75 9.87 9.53     A5 24 0
30 BD+05 3871 * 18 38 45.1849075872 +05 20 03.756885828 10.14 10.20 9.88     A8 25 0
31 IC 4756 425 * 18 38 47.2849416456 +05 16 24.979311768 14.61 14.24 13.48 13.70   G2V 14 0
32 BD+05 3872 * 18 38 49.3322921856 +05 33 18.261806256   10.98 10.44     A3 18 0
33 IC 4756 106 * 18 38 51.1389037296 +05 31 51.985029648   11.37 10.76     F: 8 0
34 BD+05 3874 SB* 18 38 52.0140425688 +05 40 20.503022232 9.94 10.00 9.62     A2 25 0
35 BD+05 3873 * 18 38 52.9301191680 +05 20 16.508925924 9.93 10.10 9.05     K0 55 0
36 IC 4756 114 * 18 38 58.6150090632 +05 29 35.638541016   11.02 10.48     A5 17 0
37 BD+05 3877 * 18 39 01.9980009360 +05 32 09.480995952 9.81 9.96 9.57     F4 24 0
38 USNO-A2.0 0900-13359235 * 18 39 04.8897778680 +05 19 34.283534088           ~ 2 0
39 UCAC4 478-088567 PM* 18 39 05.7783674136 +05 34 56.700559596       16.03   ~ 4 0
40 PM J18390+0534S ** 18 39 05.806752 +05 34 21.16416   14.36 12.90 12.44   ~ 4 0
41 IC 4756 127 * 18 39 18.5942919144 +05 23 23.854886592 10.47 10.59 10.25     A8 17 0
42 IC 4756 130 * 18 39 20.0430985512 +05 30 11.069462664   10.26 10.02     ~ 19 0
43 IC 4756 131 * 18 39 22.1578158240 +05 30 24.058451124   10.36 10.09     ~ 18 0
44 IC 4756 133 * 18 39 24.5322121224 +05 23 57.759753552 10.60 10.71 10.38     A9 17 0
45 BD+05 3888 SB* 18 39 26.5985220072 +05 21 31.862574000 10.42 10.70 9.67     G2 19 0
46 BD+05 3889 * 18 39 30.6947916360 +05 29 06.073065492 9.76 9.95 9.54     A3: 19 0
47 BD+05 3890 * 18 39 31.0846994280 +05 31 28.509949596 10.60 10.81 10.43     ~ 14 0
48 NGC 6940 OpC 20 34 28.4 +28 17 07           ~ 215 0

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