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 Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present Very Large Telescope/FORS2 time‐series spectroscopy of the Wolf–Rayet (WR) star #41 in the Sculptor group galaxy NGC 300. We confirm a physical association with NGC 300 X‐1, since radial velocity variations of the He  ii λ4686 line indicate an orbital period of 32.3 ± 0.2 h which agrees at the 2σ level with the X‐ray period from Carpano et al. We measure a radial velocity semi‐amplitude of 267 ± 8 km s −1 , from which a mass function of  2.6 ± 0.3 M ⊙   is obtained. A revised spectroscopic mass for the WN‐type companion of  26 +7  −5  M ⊙   yields a black hole mass of  20 ± 4 M ⊙   for a preferred inclination of  60°–75° . If the WR star provides half of the measured visual continuum flux, a reduced WR (black hole) mass of  15 +4  −2.5  M ⊙  (14.5 +3  −2.5  M ⊙  ) would be inferred. As such, #41/NGC 300 X‐1 represents only the second extragalactic WR plus black hole binary system, after IC 10 X‐1. In addition, the compact object responsible for NGC 300 X‐1 is the second highest stellar‐mass black hole known to date, exceeded only by IC 10 X‐1.

NGC 300 X‐1 is a Wolf–Rayet/black hole binary ★