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

The atmospheric composition of low-mass exoplanets is the object of intenseobservational and theoretical investigations. GJ3470b is a warm uranus recentlydetected in transit across a bright late-type star. The transit of this planethas already been observed in several band passes from the ground and space,allowing observers to draw an intriguing yet incomplete transmission spectrumof the planet atmospheric limb. In particular, published data in the visiblesuggest the existence of a Rayleigh scattering slope, making GJ3470b a uniquecase among the known neptunes, while data obtained beyond 2 um are consistentwith a flat infrared spectrum. The unexplored near-infrared spectral regionbetween 1 and 2 um, is thus key to undertanding the atmospheric nature ofGJ3470b. Here, we report on the first space-borne spectrum of GJ3470, obtainedduring one transit of the planet with WFC3 on board HST, operated in staremode. The spectrum covers the 1.1--1.7-um region with a resolution of about300. We retrieve the transmission spectrum of GJ3470b with a chromaticplanet-to-star radius ratio precision of 0.15% (about one scale height) per40-nm bins. At this precision, the spectrum appears featureless, in goodagreement with ground-based and Spitzer infrared data at longer wavelengths,pointing to a flat transmission spectrum from 1 to 5 um. We present newsimulations of transmission spectra for GJ3470b, which allow us to show thatthe HST/WFC3 observations rule out cloudless hydrogen-rich atmospheres (>10sigma) as well as hydrogen-rich atmospheres with tholin haze (>5 sigma). Addingour near-infrared measurements to the full set of previously published datafrom 0.3 to 5 um, we find that a cloudy, hydrogen-rich atmosphere can explainthe full transmission spectrum if, at the terminator, the clouds are located atlow pressures (<1 mbar) or the water mixing ratio is extremely low (<1 ppm).

Near-infrared transmission spectrum of the warm-uranus GJ 3470b with the Wide Field Camera-3 on the Hubble Space Telescope