New orbital ephemerides for the dipping source 4U 1323-619: constraining the distance to the source

Abstract

Context. 4U 1323-619 is a low mass X-ray binary system that shows type I X-ray bursts and dips. The most accurate estimation of the orbital period is 2.941923(36) h and a distance from the source that is lower than 11 kpc has been proposed. Aims. We aim to obtain the orbital ephemeris, the orbital period of the system, as well as its derivative to compare the observed luminosity with that predicted by the theory of secular evolution. Methods. We took the advantage of about 26 yrs of X-ray data and grouped the selected observations when close in time. We folded the light curves and used the timing technique, obtaining 12 dip arrival times. We fit the delays of the dip arrival times both with a linear and a quadratic function. Results. We locate 4U 1323-619 within a circular area centred at RA (J2000) = 201.6543• and Dec (J2000) = -62.1358• with an associated error of 0.0002• , and confirm the detection of the IR counterpart already discussed in literature. We estimate an orbital period of P = 2.9419156(6) h compatible with the estimations that are present in the literature, but with an accuracy ten times higher. We also obtain a constraint on the orbital period derivative for the first time, estimatingṖ = (8 ± 13) × 10 −12 s/s. Assuming that the companion star is in thermal equilibrium in the lower main sequence, and is a neutron star of 1.4 M , we infer a mass of 0.28±0.03 M for the companion star. Assuming a distance of 10 kpc, we obtained a luminosity of (4.3±0.5)×10 36 erg s −1 , which is not in agreement with what is predicted by the theory of secular evolution. Using a 3D extinction map of the K s radiation in our Galaxy, we obtain a distance of 4.2 +0.8 −0.7 kpc at 68% confidence level. This distance implies a luminosity estimation of (0.8 ± 0.3) × 10 36 erg s −1 , which is consistent with the adopted scenario in which the companion star is in thermal equilibrium.

Time domain astronomy with the THESEUS satellite

“…The dip arrival times of XB 1916−053 also strongly support non-conservative mass transfer [167,170]. The large FOV of SXI and XGIS will allow to monitor the light curves of the LMXBs with high inclination, thereby providing an opportunity to determine arrival times for new dip events and eclipses, and to improve constrains on orbital period decay rate for other dipping sources such as 4U 1323−619 [171] to understand their mass-transfer scenario. Finally, residuals appearing in the orbital solutions for XB 1916−053 and MXB 1659−298, suggest that these systems are hierarchical triple systems with a third body with a mass similarto Hot Jupiter extra-solar planets (see [172] and ref.…”

Time Domain Astronomy with the THESEUS Satellite

“…The dip arrival times of XB 1916−053 also strongly support non-conservative mass transfer [164,167]. The large FOV of SXI and XGIS will allow to monitor the light curves of the LMXBs with high inclination, thereby providing an opportunity to determine arrival times for new dip events and eclipses, and to improve constrains on orbital period decay rate for other dipping sources such as 4U 1323−619 [168] to understand their mass-transfer scenario. Finally, residuals appearing in the orbital solutions for XB 1916−053 and MXB 1659−298, suggest that these systems are hierarchical triple systems with a third body with a mass similarto Hot Jupiter extra-solar planets (see [169] and ref.…”

Indications of non-conservative mass transfer in AMXPs

“…"T": theoretical argument. tion maps of radiation in the K S band for our Galaxy computed by Marshall et al (2006) 5 , following the same steps by Gambino et al (2016). Even if on the basis of its location, i.e.…”