Related papers: Basic parameters of the helium accreting X-ray bur…
We report on the measurement of the mass and radius of the neutron star in the low-mass X-ray binary 4U 1820-30. The analysis of the spectroscopic data on multiple thermonuclear bursts yields well-constrained values for the apparent…
4U 1820-30 is a ultracompact X-ray binary located in the globular cluster NGC 6624, consisting of a neutron star accreting material from a helium white dwarf companion characterized by the shortest known orbital period for this type of star…
We analyze a set of Type I X-ray bursts from the low mass X-ray binary 4U 1728 -34, observed with Rossi X-ray Timing Explorer (RXTE). and we implement an analytical model of X-ray spectral formation in the neutron star (NS) atmosphere…
We present a new method for determining masses and radii of neutron stars residing in thermo-nuclear X-ray burst sources. To illustrate this method we apply it to a burst from the source 4U 1820-30 recorded by the Rossi X-Ray Timing…
4U 1820-30 is a low-mass X-ray binary near the center of the globular cluster NGC 6624 consisting of, at least, one neutron star and one helium white dwarf. Analyzing 16 years of data from the Rossi X-ray Timing Explorer (RXTE) allows us to…
Observations of thermonuclear X-ray bursts from accreting neutron stars (NSs) in low-mass X-ray binary systems can be used to constrain NS masses and radii. Most previous work of this type has set these constraints using Planck function…
The X-ray source 4U1820-30 in the globular cluster NGC 6624 is known as the most compact binary among the identified X-ray binaries. Having an orbital period of 685.0 s, the source consists of a neutron star primary and likely 0.06--0.08…
Powerful Type I X-ray burst with strong radial expansion was observed from the low mass X-ray binary 4U 1820-30 with Rossi X-ray Timing Explorer on May 2, 1997. We investigate closely the flux profile during the burst expansion stage.…
Thermal emission during X-ray bursts is a powerful tool to determine neutron star masses and radii, if the Eddington flux and the apparent radius in the cooling tail can be measured accurately, and distances to the sources are known. We…
We present the results obtained from timing and spectral studies of 15 thermonuclear X-ray bursts from 4U 1820-30 observed with the Neutron Star Interior Composition Explorer (NICER) during its five years of observations between 2017-2022.…
We use time resolved spectroscopy of thermonuclear X-ray bursts observed from SAX J1748.9-2021 to infer the mass and the radius of the neutron star in the binary. Four X-ray bursts observed from the source with RXTE enable us to measure the…
Bursting X-ray binaries in globular clusters are ideal sources for measuring neutron star masses and radii, and hence, for determining the equation of state of cold, ultradense matter. We use time-resolved spectroscopic data from EXO…
The accretion flow / jet correlation in neutron star (NS) low-mass X-ray binaries (LMXBs) is far less understood when compared to black hole (BH) LMXBs. In this paper we will present the results of a dense multi-wavelength observational…
The persistently bright ultra-compact neutron star low-mass X-ray binary 4U 1820$-$30 displays a $\sim$170 d accretion cycle, evolving between phases of high and low X-ray modes, where the 3 -- 10 keV X-ray flux changes by a factor of up to…
The Neutron Star Interior Composition Explorer (NICER) on the International Space Station (ISS) observed strong photospheric expansion of the neutron star in 4U 1820-30 during a Type I X-ray burst. A thermonuclear helium flash in the star's…
Spectral measurements of thermonuclear (type-I) X-ray bursts from low mass X-ray binaries have been used to measure neutron star (NS) masses and radii. A number of systematic issues affect such measurements and have raised concerns as to…
We perform a comprehensive study of thermonuclear bursts from the neutron star low-mass X-ray binary 4U 1702-429 detected with NICER and XMM-Newton. The thermonuclear burst detected with NICER shows clear evidence of a photospheric radius…
We analyzed 123 thermonuclear (type-I) X-ray bursts observed by the Rossi X-ray Timing Explorer from the low-mass X-ray binary 4U 1636-536. All but two of the 40 radius-exansion bursts in this sample reached peak fluxes which were normally…
Type I X-ray bursts in the ultracompact X-ray binary 4U 1820$-$30 are powered by the unstable thermonuclear burning of hydrogen-deficient material. We report the detection of 15 type I X-ray bursts from 4U 1820$-$30 observed by NICER in…
We present a recent Chandra observation of the quiescent low-mass X-ray binary containing a neutron star, located in the globular cluster M30. We fit the thermal emission from the neutron star to extract its mass and radius. We find no…