2007A&A...473..163M


Query : 2007A&A...473..163M

2007A&A...473..163M - Astronomy and Astrophysics, volume 473, 163-170 (2007/10-1)

η Chamaeleontis: abnormal initial mass function or dynamical evolution?

MORAUX E., LAWSON W.A. and CLARKE C.

Abstract (from CDS):

η Chamaeleontis is a unique young (∼9Myr) association with 18 systems concentrated in a radius of ≃35arcmin, i.e. 1pc at the cluster distance of 97pc. No other members have been found up to 1.5 degrees from the cluster centre. The cluster mass function is consistent with the IMF of other rich young open clusters in the higher mass range but shows a clear deficit of low mass stars and brown dwarfs with no objects below 0.1M. The aim of this paper is to test whether this peculiar mass function could result from dynamical evolution despite the young age of the cluster. We performed N-body numerical calculations starting with a log-normal IMF and different initial conditions in terms of number of systems and cluster radius using the code NBODY3. We simulated the cluster dynamical evolution over 10Myr and compared the results to the observations. We found that it is possible to reproduce η Cha when starting with a very compact configuration (with Ninit=40 and R0=0.005pc) which suggests that the IMF of the association might not be abnormal. The high initial density might also explain the deficit of wide binaries that is observed in the cluster.

Abstract Copyright:

Journal keyword(s): stars: low-mass, brown dwarfs - stars: luminosity function, mass function - methods: N-body simulations - open clusters and associations: individual: η Chamaeleontis

Simbad objects: 12

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Number of rows : 12
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 ECHA J0836.2-7908 LM* 08 36 10.7009266536 -79 08 18.356133120     17.5     M5.5 32 0
2 V* EG Cha Or* 08 36 56.2143359952 -78 56 45.633633000   11.82 10.457   9.010 K4Ve 92 0
3 ECHA J0838.9-7916 LM* 08 38 51.4849263144 -79 16 13.752884532   16.82 16.4     M5 32 0
4 * eta Cha * 08 41 19.5125857944 -78 57 48.105898056 5.02 5.351 5.453     B8V 225 0
5 HD 75505 * 08 41 44.7049093968 -79 02 53.258689068   7.55 7.38     A1V 51 0
6 NAME eta Cha Association OpC 08 42 33 -78 57.8           ~ 351 0
7 V* EM Cha Or* 08 43 07.2443828304 -79 04 52.483961064     10.8     K3 55 0
8 * 9 Cha SB* 08 43 12.1984130688 -79 04 12.368512452   6.28 6.07     A7V 222 0
9 V* EN Cha Or* 08 44 16.421808 -78 59 08.06316   16.425 14.967 14.688   M4 59 0
10 V* EQ Cha TT* 08 47 56.7585043512 -78 54 53.185560516   14.777 13.308 12.802 10.795 M3 77 0
11 V* TW Hya TT* 11 01 51.9053285064 -34 42 17.033218380   11.94 10.50 10.626 9.18 K6Ve 1791 1
12 NAME TW Hya Association As* 11 01.9 -34 42           ~ 907 0

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2023.02.04-10:53:22

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