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

NGC1313 X-2 was among the first ultraluminous X-ray sources discovered, andhas been a frequent target of X-ray and optical observations. Using the HST/ACSmulti-band observations, this source is identified with a unique counterpartwithin an error circle of $0\farcs2$. The counterpart is a blue star on theedge of a young cluster of $\le10^7$ years amid a dominant old stellarpopulation. Its spectral energy distribution is consistent with that for aZ=0.004 star with 8.5 $M_\odot$ about $5\times10^6$ years old, or for an O7 Vstar at solar metallicity. The counterpart exhibited significant variability of$\Delta m = 0.153\pm0.033$ mag between two F555W observations separated bythree months, reminiscent of the ellipsoidal variability due to the orbitalmotion of this ULX binary.Comment: 21 pages, 7 figures, scheduled for the ApJ June 10, 2007, v662n 1  issu

Optical Studies of the Ultraluminous X‐Ray Source NGC 1313 X‐2