We have used phase-resolved high-resolution images and low resolution spectra taken at the ESO Very Large Telescope, to study the properties of the low-mass Helium White Dwarf companion to the millisecond pulsar (hereafter COM~J1911$-$5958A), in the halo of the Galactic Globular Cluster NGC 6752. The radial velocity curve confirms that com is orbiting the pulsar and allows to derive a systemic velocity of the binary system nicely in agreement with that of NGC 6752. This strongly indicates that the system is a member of the cluster, despite its very offset position ($sim 74$ core radii) with respect to the core. Constraints on the orbital inclination ($gapp 70^circ$) and pulsar mass ($1.2-1.5~{rm M_odot}$) are derived from the mass ratio $M_{PSR}/M_{COM}= 7.49pm0.64$ and photometric properties of COM~J1911$-$5958A. The light curve in B-band shows two phases of unequal brightening ($Delta$mag$sim 0.3$ and $0.2$, respectively) located close to quadratures and superimposed on an almost steady baseline emission: this feature is quite surprising and needs to be further investigated.
Cocozza G., Ferraro F.R., Possenti A., D'Amico N. (2006). The puzzling properties of the Helium White Dwarf orbiting the millisecond pulsar PSR J1911$-$5958A in NGC 6752. THE ASTROPHYSICAL JOURNAL, 641, L129-L132 [10.1086/504040].
The puzzling properties of the Helium White Dwarf orbiting the millisecond pulsar PSR J1911$-$5958A in NGC 6752
COCOZZA, GABRIELE;FERRARO, FRANCESCO ROSARIO;
2006
Abstract
We have used phase-resolved high-resolution images and low resolution spectra taken at the ESO Very Large Telescope, to study the properties of the low-mass Helium White Dwarf companion to the millisecond pulsar (hereafter COM~J1911$-$5958A), in the halo of the Galactic Globular Cluster NGC 6752. The radial velocity curve confirms that com is orbiting the pulsar and allows to derive a systemic velocity of the binary system nicely in agreement with that of NGC 6752. This strongly indicates that the system is a member of the cluster, despite its very offset position ($sim 74$ core radii) with respect to the core. Constraints on the orbital inclination ($gapp 70^circ$) and pulsar mass ($1.2-1.5~{rm M_odot}$) are derived from the mass ratio $M_{PSR}/M_{COM}= 7.49pm0.64$ and photometric properties of COM~J1911$-$5958A. The light curve in B-band shows two phases of unequal brightening ($Delta$mag$sim 0.3$ and $0.2$, respectively) located close to quadratures and superimposed on an almost steady baseline emission: this feature is quite surprising and needs to be further investigated.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
