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 Tools annual

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 monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

We present a theory for interpreting the sodium lines detected intransmission spectra of exoplanetary atmospheres. Previous analyses employedthe isothermal approximation and dealt only with the transit radius. Byrecognising the absorption depth and the transit radius as being independentobservables, we develop a theory for jointly interpreting both quantities,which allows us to infer the temperatures and number densities associated withthe sodium lines. We are able to treat a non-isothermal situation with aconstant temperature gradient. Our novel diagnostics take the form ofsimple-to-use algebraic formulae and require measurements of the transit radii(and their corresponding absorption depths) at line center and in the line wingfor both sodium lines. We apply our diagnostics to the HARPS data of HD189733b, confirm the upper atmospheric heating reported by Huitson et al.(2012), derive a temperature gradient of $0.4376 \pm 0.0154$ K km$^{-1}$ andfind densities $\sim 1$ to $10^4$ cm$^{-3}$.

A Non-isothermal Theory for Interpreting Sodium Lines in Transmission Spectra of Exoplanets