2012A&A...546A.117G


C.D.S. - SIMBAD4 rel 1.7 - 2020.09.19CEST06:01:09

2012A&A...546A.117G - Astronomy and Astrophysics, volume 546A, 117-117 (2012/10-1)

Dynamo regime transition among sun-like stars in M 34. A time evolution model of X-ray activity on the main sequence.

GONDOIN P.

Abstract (from CDS):

The X-ray emission from late-type stars in open clusters exhibits two kinds of dependences on stellar rotation. While fast rotators have a relatively constant X-ray emission level, slower rotators show a decline of their X-ray emission with decreasing rotation rate. The physical significance of the transition between these two X-ray emission regimes is a matter of debate. During the ∼500Myr period of stellar evolution that separates the Pleiades from the Hyades, late-type stars such as those present in the M34 open cluster undergo significant changes in their rotation rates. These could affect the dynamo processes in their interiors, possibly altering their surface magnetic fluxes. The purpose of the present study is to look for the X-ray signatures of such possible modifications, to search for correlations with rotation and stellar parameters, and to propose a parameterization of the X-ray activity evolution on the main sequence. The aim is to provide observational constraints on the time evolution of dynamo processes in the interiors of late-type stars. The distributions of stellar X-ray luminosities vs. rotation periods and Rossby numbers of a sample of M34 late-type stars are compared with rotation-activity relationships established in a large sample of cluster members and field stars. A model of X-ray activity evolution is developed by combining an X-ray activity-rotation relationship with a recent model of stellar rotation evolution on the main sequence. The distribution of stellar X-ray luminosities in M34 is compared with this model. A correlation is observed between the saturated and non-saturated regime of X-ray emission and the C- and I-rotational sequences that have been observed in M34 from extensive rotational periods surveys. M34 sample stars show a steep transition in X-ray to bolometric luminosity ratio between the C-sequence and gap stars that emit close to the 10–3 saturation level, and the I-sequence stars, whose LX/Lbol ratio is significantly lower for similar values of the Rossby number. A comparison between X-ray emission vs. mass distribution in M34 and the X-ray luminosity evolution model suggests that the transition between the saturated and non-saturated regime of X-ray emission occurs in M34 cluster members depending on their convective turnover time and period of rotation. I argue that the drop of (LX/Lbol) by one order of magnitude observed in M34 around a Rossby number of 0.3 is indicative of a change in dynamo efficiency. I conclude that the transition from the saturated to the non-saturated regime of X-ray emission among main-sequence stars is the result of a dynamo regime transition, possibly between a turbulent dynamo and an interface-type dynamo.

Abstract Copyright:

Journal keyword(s): open clusters and associations: individual: M 34 - stars: activity - stars: atmospheres - stars: late-type - stars: magnetic field - stars: rotation

Simbad objects: 53

goto Full paper

goto View the reference in ADS

Number of rows : 53

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 752 OpC 01 57 41 +37 47.1           ~ 541 0
2 Cl* NGC 1039 JP 1 * 02 40 35.89 +42 42 30.9     14.38     ~ 2 0
3 LB 3568 blu 02 40 40.0502327545 +42 46 32.341919727   18.5       ~ 3 0
4 NGC 1039 147 * 02 40 54.4485468083 +42 57 57.008037571   12.9 12.68     F2 6 0
5 [MMS2011] 8 Ro* 02 40 57.994 +42 49 44.61   17.993 17.136   16.075 ~ 3 0
6 [MMS2011] 9 * 02 41 04.32 +42 35 11.5           ~ 2 0
7 2MASS J02413016+4227555 * 02 41 30.1670811025 +42 27 55.361985546           ~ 4 0
8 [MMS2011] 5 * 02 41 31.45 +42 59 05.8           ~ 2 0
9 NGC 1039 204 * 02 41 33.5878164862 +42 32 22.391381343   12.96 12.33     G0? 9 0
10 V* V797 Per BY* 02 41 35.2552335513 +42 41 02.488855992   15.406 14.546   13.552 ~ 8 0
11 V* V802 Per BY* 02 41 43.8644873568 +42 45 08.135710161   18.415 17.009   15.260 ~ 6 0
12 2XMM J024147.3+424339 Ro* 02 41 47.3934772452 +42 43 38.753447570   13.765 13.151   12.433 ~ 8 0
13 V* V807 Per BY* 02 41 48.4792949956 +42 49 33.619096588   17.385 16.242   14.830 ~ 5 0
14 [MMS2011] 2 * 02 41 50.60 +43 01 26.8           ~ 2 0
15 V* V813 Per BY* 02 41 53.2453209361 +42 35 26.294769082   17.519 16.294 15.59 14.660 ~ 4 0
16 V* V817 Per BY* 02 41 55.2557214741 +42 50 31.758982083           ~ 3 0
17 [MMS2011] 23 Ro* 02 41 57.472 +43 00 26.53   16.564 15.503   14.241 ~ 6 0
18 V* V821 Per BY* 02 42 01.8119267123 +42 41 58.978467326           ~ 3 0
19 NGC 1039 OpC 02 42 05 +42 45.7           ~ 371 0
20 [MMS2011] 21 * 02 42 05.12 +42 25 26.5           ~ 2 0
21 Cl* NGC 1039 IAH 1-1178 * 02 42 06.4954407125 +42 39 37.275043364           ~ 3 0
22 [MMS2011] 3 * 02 42 10.51 +42 46 33.2           ~ 2 0
23 V* V837 Per BY* 02 42 17.2376026803 +42 48 18.652882839   17.02 15.86     ~ 7 0
24 Cl* NGC 1039 JP 358 * 02 42 17.4201729234 +42 35 04.043073929   16.16 15.84     ~ 3 0
25 [MMS2011] 24 * 02 42 26.03 +42 48 53.9           ~ 2 0
26 V* V846 Per BY* 02 42 31.5396315590 +42 37 10.525981438   17.01 15.93     ~ 9 0
27 V* V847 Per BY* 02 42 32.2842386701 +42 49 05.943144139   16.1 15.02     ~ 9 0
28 NGC 1039 352 * 02 42 34.3229463634 +42 36 22.246541001   13.05 12.40 12.27   ~ 9 0
29 V* V852 Per BY* 02 42 35.0218986137 +42 39 28.968282929           ~ 3 0
30 V* V857 Per BY* 02 42 41.8213901579 +42 46 01.779622807           ~ 2 0
31 NGC 1039 367 * 02 42 42.4476381011 +42 40 31.435952056   13.17 12.82     ~ 7 0
32 V* V861 Per BY* 02 42 47.5494528859 +42 45 46.815060250   17.81 16.68     ~ 5 0
33 [MMS2011] 28 * 02 42 47.89 +43 00 47.2           ~ 2 0
34 UCAC4 664-012210 ** 02 42 49.202688 +42 40 15.38724   15.85 14.98 14.87   ~ 2 0
35 V* V864 Per BY* 02 42 50.7704145115 +42 58 07.849637636     14.88     ~ 6 0
36 V* V868 Per BY* 02 42 57.8370602317 +42 58 03.854554240   15.79 14.85     ~ 6 0
37 V* V869 Per BY* 02 42 57.8768837180 +42 41 46.566083183     16.53     ~ 4 0
38 V* V870 Per BY* 02 42 59.9529847282 +42 58 01.517347849   16.67 15.67     ~ 6 0
39 Cl* NGC 1039 IAH 4-2533 * 02 43 01.9936187865 +42 46 54.210778969           ~ 4 0
40 Cl* NGC 1039 JP 582 * 02 43 13.1022616006 +42 50 25.455254701     16.15     ~ 3 0
41 LAMOST J024323.79+423059.0 * 02 43 23.7982999541 +42 30 59.006474943           ~ 5 0
42 Cl* NGC 1039 JP 612 * 02 43 30.2815900548 +42 53 02.622499319   15.81 14.88     ~ 4 0
43 Cl* NGC 1039 IS 298 * 02 43 31.9610566562 +42 38 31.559239498   14.25 13.52     ~ 6 0
44 Cl Melotte 20 OpC 03 26 42 +48 48.0           ~ 753 0
45 Cl Melotte 22 OpC 03 47 00 +24 07.0           ~ 3005 0
46 Cl Melotte 25 OpC 04 26 54.00 +15 52 00.0           ~ 2681 0
47 NGC 2516 OpC 07 58 04 -60 45.2           ~ 592 0
48 NGC 2547 OpC 08 09 52.360 -49 10 35.01           ~ 315 0
49 NGC 2632 OpC 08 40 24 +19 40.0           ~ 1246 0
50 IC 2391 OpC 08 40 32 -53 02.0           ~ 722 0
51 IC 2602 OpC 10 42 58 -64 24.0           ~ 556 0
52 NGC 3532 OpC 11 05 39 -58 45.2           ~ 267 0
53 NGC 6475 OpC 17 53 51 -34 47.6           ~ 338 0

    Equat.    Gal    SGal    Ecl

To bookmark this query, right click on this link: simbad:objects in 2012A&A...546A.117G and select 'bookmark this link' or equivalent in the popup menu


2020.09.19-06:01:09

© Université de Strasbourg/CNRS

    • Contact