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

I report on close encounters of stars to the Sun found in the first Gaia datarelease (GDR1). Combining Gaia astrometry with radial velocities of around 320000 stars drawn from various catalogues, I integrate orbits in a Galacticpotential to identify those stars which pass within a few parsecs. Suchencounters could influence the solar system, for example through gravitationalperturbations of the Oort cloud. 16 stars are found to come within 2 pc(although a few of these have dubious data). This is fewer than were found in asimilar study based on Hipparcos data, even though the present study has manymore candidates. This is partly because I reject stars with large radialvelocity uncertainties (>10 km/s), and partly because of missing stars in GDR1(especially at the bright end). The closest encounter found is Gl 710, a Kdwarf long-known to come close to the Sun in about 1.3 Myr. The Gaia astrometrypredict a much closer passage than pre-Gaia estimates, however: just 16 000 AU(90% confidence interval: 10 000 to 21 000 AU), which will bring this star wellwithin the Oort cloud. Using a simple model for the spatial, velocity, andluminosity distributions of stars, together with an approximation of theobservational selection function, I model the incompleteness of this Gaia-basedsearch as a function of the time and distance of closest approach. Applyingthis to a subset of the observed encounters (excluding duplicates and starswith implausibly large velocities), I estimate the rate of stellar encounterswithin 5 pc averaged over the past and future 5 Myr to be 545 +/- 59 per Myr.Assuming a quadratic scaling of the rate within some encounter distance (whichmy model predicts), this corresponds to 87 +/- 9 per My within 2 pc. A moreaccurate analysis and assessment will be possible with future Gaia datareleases.

The completeness-corrected rate of stellar encounters with the Sun from the first Gaia data release