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

Context. Young loose nearby associations are unique samples of close (<150pc), young (approx 5-100 Myr) pre-main sequence (PMS) stars. A significantnumber of members of these associations have been identified in the SACYcollaboration. We can use the proximity and youth of these members toinvestigate key ingredients in star formation processes, such as multiplicity.  Aims. We present the statistics of identified multiple systems from 113confirmed SACY members. We derive multiplicity frequencies, mass-ratio, andphysical separation distributions in a consistent parameter space, and compareour results to other PMS populations and the field.  Methods. We have obtained adaptive-optics assisted near-infrared observationswith NACO (ESO/VLT) and IRCAL (Lick Observatory) for at least one epoch of all113 SACY members. We have identified multiple systems using co-movingproper-motion analysis and using contamination estimates. We have exploredranges in projected separation and mass-ratio of a [3-1000 au], and q [0.1-1],respectively.  Results. We have identified 31 multiple systems (28 binaries and 3 triples).We derive a multiplicity frequency (MF) of MF_(3-1000au)=28.4 +4.7, -3.9% and atriple frequency (TF) of TF_(3-1000au)=2.8 +2.5, -0.8% in the separation rangeof 3-1000 au. We do not find any evidence for an increase in the MF withprimary mass. The estimated mass-ratio of our statistical sample (withpower-law index gamma=-0.04 +/- 0.14) is consistent with a flat distribution(gamma = 0).  Conclusions. We show further similarities (but also hints of discrepancies)between SACY and the Taurus region: flat mass-ratio distributions andstatistically similar MF and TF values. We also compared the SACY sample to thefield (in the separation range of 19-100 au), finding that the twodistributions are indistinguishable, suggesting a similar formation mechanism.

astronomy and astrophysics

Search for associations containing young stars (SACY). VI. Is  multiplicity universal? Stellar multiplicity in the range 3-1000 au from  adaptive-optics observations