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 present new near-infrared spectra, obtained at Gemini Observatory, for twoY dwarfs: WISE J035000.32-565830.2 (W0350) and WISEP J173835.52+273258.9(W1738). A FLAMINGOS-2 R=540 spectrum was obtained for W0350, covering 1.0 <lambda um < 1.7, and a cross-dispersed GNIRS R=2800 spectrum was obtained forW1738, covering 0.993-1.087 um, 1.191-1.305 um, 1.589-1.631 um, and 1.985-2.175um, in four orders. We also present revised YJH photometry for W1738, using newNIRI Y and J imaging, and a re-analysis of the previously published NIRI H bandimages. We compare these data, together with previously published data forlate-T and Y dwarfs, to cloud-free models of solar metallicity, calculated bothin chemical equilibrium and with disequilibrium driven by vertical transport.We find that for the Y dwarfs the non-equilibrium models reproduce thenear-infrared data better than the equilibrium models. The remainingdiscrepancies suggest that fine-tuning the CH_4/CO and NH_3/N_2 balance isneeded. Improved trigonometric parallaxes would improve the analysis. Despitethe uncertainties and discrepancies, the models reproduce the observednear-infrared spectra well. We find that for the Y0, W1738, T_eff = 425 +/- 25K and log g = 4.0 +/- 0.25, and for the Y1, W0350, T_eff = 350 +/- 25 K and logg = 4.0 +/- 0.25. W1738 may be metal-rich. Based on evolutionary models, thesetemperatures and gravities correspond to a mass range for both Y dwarfs of 3-9Jupiter masses, with W0350 being a cooler, slightly older, version of W1738;the age of W0350 is 0.3-3 Gyr, and the age of W1738 is 0.15-1 Gyr.

Near-Infrared Spectroscopy of the Y0 WISEP J173835.52+273258.9 and the Y1 WISE J035000.32-565830.2: the Importance of Non-Equilibrium Chemistry