VizieR Online Data Catalog: New L subdwarfs, population properties (Zhang+, 2018)

The L subdwarf candidates in our programme were generally selected from the UKIDSS Large Area Survey (LAS) and the SDSS, following the selection criteria/procedure described in Paper I (Zhang et al. 2017MNRAS.464.3040Z). In addition two extra candidates without SDSS detections were selected from a ULAS proper motion catalogue (Smith et al. 2014MNRAS.437.3603S, Cat. J/MNRAS/437/3603). Our programmatic candidate sample consisted of 64 objects of which five had been confirmed as L subdwarfs by other studies. We have spectroscopically followed up the remaining 59 candidates, which has in total resulted in the confirmation/study of 34 L subdwarfs. Eight of these were published in Papers I (Zhang et al. 2017MNRAS.464.3040Z) and III (Zhang et al. 2018MNRAS.479.1383Z), and the remaining 27 are reported here. Table 1 presents optical and NIR photometry for all known L subdwarfs, which includes the 34 studied by our programme plus 31 from elsewhere in the literature. Candidates have been followed up with optical spectroscopy using the Optical System for Imaging and low-Resolution Integrated Spectroscopy (OSIRIS; Cepa et al. 2000SPIE.4008..623C) instrument on the Gran Telescopio Canarias (GTC) since 2012. Table 2 shows a summary of our GTC spectroscopic observations. We have also obtained optical-NIR spectroscopy of five of our candidates, a known sdL8 subdwarf and three radial velocity standard L dwarfs using the X-shooter spectrograph (Vernet et al. 2011A&A...536A.105V) on the Very Large Telescope (VLT) since 2014. Table 3 shows a summary of our VLT spectroscopic observations. Finally, twenty of 66 known L subdwarfs in Table 1 were observed by Gaia. Table 9 shows the Gaia astrometry and photometry of these 20 L subdwarfs. As our UKIDSS-SDSS survey is relatively deep, only two of our L subdwarfs are in Gaia DR2; UL0753+20 is from this work and ULAS J134749.79+333601.7 was presented in Paper I.

(8 data files).