English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We report on optical spectroscopy of the eclipsing Halo LMXB 2S0921-630, thatreveals the absorption line radial velocity curve of the K0III secondary starwith a semi-amplitude K_2=92.89 +/- 3.84 km/s, a systemic velocity$\gamma$=34.9 +/- 3.3 \kms and an orbital period P_orb of 9.0035 +/- 0.0029 day(1-sigma). Given the quality of the data, we find no evidence for the effectsof X-ray irradiation. Using the previously determined rotational broadening ofthe mass donor, and applying conservative limits on the orbital inclination, weconstrain the compact object mass to be 2.0-4.3 Msolar (1-sigma), ruling out acanonical neutron star at the 99% level. Since the nature of the compact objectis unclear, this mass range implies that the compact object is either alow-mass black hole with a mass slightly higher than the maximum neutron starmass (2.9 Msolar) or a massive neutron star. If the compact object is a blackhole, it confirms the prediction of the existence of low-mass black holes,while if the object is a massive neutron star its high mass severely constrainsthe equation of state of nuclear matter.Comment: Accepted by ApJ

The Massive Neutron Star or Low-Mass Black Hole in 2S 0921-630