2001A&A...379..872D


Query : 2001A&A...379..872D

2001A&A...379..872D - Astronomy and Astrophysics, volume 379, 872-877 (2001/12-1)

Microlensing planets in M 22: Free-floating or bound?

DE LA FUENTE MARCOS R. and DE LA FUENTE MARCOS C.

Abstract (from CDS):

We use detailed numerical simulations and theoretical estimates to show that, if confirmed, the unusually brief microlensing events observed by Sahu et al. (2001Natur.411.1022S) in the field of the globular cluster M 22 might be explained as a result of microlensing by a population of clustered MACHOs, a dark cluster or RAMBO, not associated with the globular cluster. If real, this dark cluster would be located between M 22 and the Galactic bulge and could include at least 106 substellar members with a typical size of 1-3pc. Bound planets in wide or/and eccentric orbits are also able to reproduce the observed microlensing behaviour, but only if multiplanet systems (including large Kuiper-belt-like objects) are abundant, although, our calculations argue against the latter scenario as the ionization rate in M 22 is very high. Dynamically ejected or lone planets are, in principle, incompatible with the observational findings as they either escape their parent cluster in a relatively short time-scale after ejection or segregate toward the outskirts of the cluster. We discuss additional implications of the dark cluster scenario, including the existence of a population of RAMBOs toward the Galactic bulge.

Abstract Copyright:

Journal keyword(s): celestial mechanics - stellar dynamics - dark matter - Galaxy: globular clusters: individual: NGC 6656 - globular clusters: general - gravitational lensing - planetary systems

Simbad objects: 5

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Number of rows : 5
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 NGC 3201 GlC 10 17 36.82 -46 24 44.9           ~ 888 0
2 NGC 5139 GlC 13 26 47.28 -47 28 46.1           ~ 3433 0
3 M 4 GlC 16 23 35.22 -26 31 32.7           ~ 1856 0
4 M 22 GlC 18 36 23.94 -23 54 17.1           ~ 1381 0
5 M 71 GlC 19 53 46.49 +18 46 45.1           ~ 1130 0

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