We analyse the photometric, chemical, star formation history and structural properties of the brightest globular cluster (GC) in M81, referred to as GC1 in this work, with the intention of establishing its nature and origin. We find that it is a metal-rich ([Fe/H] = -0.60 +/- 0.10), alpha-enhanced ([alpha/Fe] similar to 0.20 +/- 0.05), core-collapsed (core radius r(c) = 1.2 pc, tidal radius r(t) = 76r(c)), old (> 13 Gyr) cluster. It has an ultraviolet excess equivalent of similar to 2500 blue horizontal branch stars. It is detected in X-rays indicative of the presence of low-mass binaries. With a mass of 1.0 x 10(7) M-circle dot, the cluster is comparable in mass to M31-G1 and is four times more massive than omega Cen. The values of r(c), absolute magnitude and mean surface brightness of GC1 suggest that it could be, like massive GCs in other giant galaxies, the left-over nucleus of a dissolved dwarf galaxy.

On the nature of the brightest globular cluster in M81 / Mayya, Y. D.; Rosa Gonzalez, D.; Santiago Cortes, M.; Rodriguez Merino, L. H.; Vega, O.; Torres Papaqui, J. P.; Bressan, Alessandro; Carrasco, L.. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - ISSN 0035-8711. - 436:3(2013), pp. 2763-2773. [10.1093/mnras/stt1784]

On the nature of the brightest globular cluster in M81

Bressan, Alessandro;
2013

Abstract

We analyse the photometric, chemical, star formation history and structural properties of the brightest globular cluster (GC) in M81, referred to as GC1 in this work, with the intention of establishing its nature and origin. We find that it is a metal-rich ([Fe/H] = -0.60 +/- 0.10), alpha-enhanced ([alpha/Fe] similar to 0.20 +/- 0.05), core-collapsed (core radius r(c) = 1.2 pc, tidal radius r(t) = 76r(c)), old (> 13 Gyr) cluster. It has an ultraviolet excess equivalent of similar to 2500 blue horizontal branch stars. It is detected in X-rays indicative of the presence of low-mass binaries. With a mass of 1.0 x 10(7) M-circle dot, the cluster is comparable in mass to M31-G1 and is four times more massive than omega Cen. The values of r(c), absolute magnitude and mean surface brightness of GC1 suggest that it could be, like massive GCs in other giant galaxies, the left-over nucleus of a dissolved dwarf galaxy.
436
3
2763
2773
https://doi.org/10.1093/mnras/stt1784
Mayya, Y. D.; Rosa Gonzalez, D.; Santiago Cortes, M.; Rodriguez Merino, L. H.; Vega, O.; Torres Papaqui, J. P.; Bressan, Alessandro; Carrasco, L.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.11767/14886
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