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 report the initial results of a large-scale optical-near infrared surveyto extend the known young population of the entire Orion star-forming regiondown to the substellar domain. Using deep optical I-band photometry and datafrom the 2MASS survey, we selected candidates across ~14.8 deg^2 in the ~8 Myrold Ori OB1a subassociation and over ~6.7 deg^2 in the Ori OB1b subassociation(age ~3), with completeness down to 0.05Mo and 0.072Mo respectively. Weobtained low resolution optical spectra for a subsample of 4 candidates in OriOB1a and 26 in Ori OB1b; as a result we confirmed 3 new members in Ori OB1a,one of which is substellar, and 19 new members in Ori OB1b, out of which 7 areat the substellar limit and 5 are substellar. We looked into the presence ofaccretion signatures by measuring the strength of the Ha line in emission.Accordingly, we classified the new members as having Classical T-Tauri star(CTTS) or Weak Lined T Tauri star-like (WTTS) nature. We found that all the newmembers confirmed in Ori OB1a are WTTSs, while 39 +25/-22 % of the new membersin Ori OB1b exhibit CTTS-like behavior, suggestive of ongoing accretion from acircum(sub)stellar disk. Additionally we found that none of the membersconfirmed in OB1a show near-IR color excess while 38 +26/-21 % of OB1b membersshow H-K color excess. These results are consistent with recent findings forlow mass young stars in Orion OB1. The similarity in CTTS-like properties andnear-IR excess across the substellar boundary gives support to the idea of acommon formation mechanism for low mass stars and at least the most massivebrown dwarfs. Finally, we remark the discovery of two new members classified asCTTSs, both exhibiting W(Ha) < -140 A, suggesting significant ongoingaccretion.

A large-scale optical-near infrared survey for brown dwarfs and very low-mass stars in the Orion OB1 association