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

We present the first results of a ground-based programme conducted on 1-4mclass telescopes. Our sample consists of 1097 active and presumably youngstars, all of them being optical counterparts of RASS X-ray sources in thenorthern hemisphere. We concentrate on the 704 optically brightest(V_Ticho<=9.5 mag) candidates. We acquired high-res spectroscopy in theHalpha/Li spectral regions for 426 of such stars without relevant literaturedata. We describe the sample and the observations and we start to discuss itsphysical properties. We used a cross-correlation technique and other tools toderive accurate radial/rotational velocities and to perform a spectralclassification for both single and SB2 stars. The spectral subtractiontechnique was used to derive chromospheric activity levels and Li abundances.We estimated the fraction of young single stars and multiple systems in stellarsoft X-ray surveys and the contamination by more evolved systems, like RSCVn's. We classified stars on the basis of Li abundance and give a glimpse oftheir sky distribution. The sample appears to be a mixture of youngPleiades-/Hyades- like stars plus an older Li-poor population (~1-2 Gyr). 7stars with Li abundance compatible with the age of IC 2602 (~30 Myr) or youngerwere detected as well, although 2 appear to be Li-rich giants. The discovery ofa large number of Li-rich giants is another outcome of this survey. Thecontamination of soft X-ray surveys by old systems in which the activity levelis enhanced by tidal synchronisation is not negligible, especially for K-typestars. 5 stars with Li content close to the primordial abundance are probablyassociated with known moving groups in the solar neighbourhood. Some of themare PTTS candidates according to their positions in the HR diagram.

A spectroscopic survey of the youngest field stars in the solar neighbourhood. I. The optically bright sample