Spiders are millisecond pulsars in compact binary systems. The variable optical emission from their companion stars reveals how the relativistic pulsar wind irradiates the companion and interacts with its outflowing matter. By modelling this optical emission, we can precisely constrain the fundamental parameters of spiders and find super-massive neutron stars, which are usually hosted in…
Compact millisecond pulsar (MSP) binaries are crucial for understanding the formation of massive pulsars and the boundary between neutron stars (NSs) and black holes (BHs). Often referred to as “spiders” due to the cannibalistic interaction between the pulsar and its companion, these systems are broadly categorized into redbacks (RBs, with companion masses between 0.1 and…
Spectroscopic studies of compact binary millisecond pulsars (‘spiders’) are crucial for finding the most massive neutron stars. Using the largest ground-based optical telescopes to take spectra of spider binaries over their orbits, we can measure the radial velocity of their companion stars, which are bright in optical wavelengths, to weigh their neutron stars, which are…
Compact binary millisecond pulsars, also known as “spiders”, host the most massive neutron stars ever observed to date. Expanding the currently known spider population holds the key to determining the maximum neutron star mass, which has crucial implications for astrophysics, nuclear physics and gravitational wave astronomy. Searching for the variable optical emission of their companions…
Compact binary millisecond pulsar systems can host some of the most massive neutron stars. These rapidly rotating neutron stars are orbited by a much less massive companion star, which can be heated by high energy particles from the pulsar wind, causing it to become irradiated. This, along with additional sources of heating from the surface…
Pulsar radio emission, associated with rapidly spinning neutron stars, enables the estimation of their distances in the Galaxy through dispersion measure (DM). The DM quantifies the dispersive delay experienced by electromagnetic radiation as it traverses ionized matter, such as the interstellar medium (ISM). By measuring this delay across a range of frequencies, astronomers can obtain…
Compact binary millisecond pulsars are captivating celestial objects comprised of fast-spinning neutron stars orbiting closely with lighter companion stars. Neutron stars are ultra-dense remnants of massive stars resulting from supernova explosions at the culmination of their lifecycles. These binary pulsars exhibit distinct behaviors due to intense gravitational interactions between the stars. Pulsars emit particle “winds”…
We present the first multi-band optical light curves of PSR J1622-0315, among the most compact known redback binary millisecond pulsars, with an orbital period Porb=3.9 h. We find a flux modulation with two maxima per orbital cycle and a peak-to-peak amplitude of about 0.3 mag, which we attribute to the ellipsoidal shape of the tidally distorted companion star. The optical colours imply a late-F to early-G spectral type companion and do not show any detectable temperature changes along the orbit. This suggests that the irradiation of the star’s inner face by the pulsar wind is unexpectedly missing despite its short orbital period.
A team of researchers from the Instituto de Astrofísica de Canarias (IAC), the University of Manchester and the Norwegian University of Science and Technology have detected an anomalously high lithium abundance in the atmosphere of the companion star of a binary millisecond pulsar. The lithium abundance is higher compared to stars with the same effective temperature and high-metallicity stars and so the study provides unambiguous evidence for fresh lithium production.
Researchers from the UPC and the IAC discover one of the most massive neutron stars. Using a pioneering method, researchers from the Astronomy and Astrophysics Group of the Universitat Politècnica de Catalunya (UPC) and the Canary Islands Institute of Astrophysics (IAC) have found a neutron star of about 2.3 solar masses—one of the most massive…