We report on the identification of the optical counterpart to the recently detected INTEGRAL transient IGR J1824-24525 in the Galactic globular cluster M28. From analysis of a multi-epoch Hubble Space Telescope data set, we have identified a strongly variable star positionally coincident with the radio and Chandra X-ray sources associated with the INTEGRAL transient. The star has been detected during both a quiescent and an outburst state. In the former case it appears as a faint, unperturbed main-sequence star, while in the latter state it is about two magnitudes brighter and slightly bluer than main-sequence stars. We also detected Hα excess during the outburst state, suggestive of active accretion processes by the neutron star.
THE OPTICAL COUNTERPART TO THE X-RAY TRANSIENT IGR J1824–24525 IN THE GLOBULAR CLUSTER M28 / C. Pallanca;E. Dalessandro;F. R. Ferraro;B. Lanzoni;G. Beccari. - In: THE ASTROPHYSICAL JOURNAL. - ISSN 0004-637X. - STAMPA. - 773:(2013), pp. 122-127. [10.1088/0004-637X/773/2/122]
THE OPTICAL COUNTERPART TO THE X-RAY TRANSIENT IGR J1824–24525 IN THE GLOBULAR CLUSTER M28
PALLANCA, CRISTINA;DALESSANDRO, EMANUELE;FERRARO, FRANCESCO ROSARIO;LANZONI, BARBARA;
2013
Abstract
We report on the identification of the optical counterpart to the recently detected INTEGRAL transient IGR J1824-24525 in the Galactic globular cluster M28. From analysis of a multi-epoch Hubble Space Telescope data set, we have identified a strongly variable star positionally coincident with the radio and Chandra X-ray sources associated with the INTEGRAL transient. The star has been detected during both a quiescent and an outburst state. In the former case it appears as a faint, unperturbed main-sequence star, while in the latter state it is about two magnitudes brighter and slightly bluer than main-sequence stars. We also detected Hα excess during the outburst state, suggestive of active accretion processes by the neutron star.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.