GeminiFocus July 2018 | Page 13

and no hydrogen sulfide is detectable . These differences were likely imprinted within the proto-solar nebula , where the balance between the amounts of nitrogen and sulphur was determined by the temperature , and therefore the location , of a given planet ’ s formation .
As reported widely in the media , in establishing a lower limit to the amount of H 2
S in the upper atmosphere of Uranus , these results not only confirm that the planet is a poisonous , frozen environment utterly hostile to life as we know it , but that its prevailing aroma is also downright offensive . More upliftingly , the study also highlights the importance of our far-flung seventh planet for understanding the early history of our Solar System , as well as the likely conditions on similarly large , icy worlds beyond the Solar System .
Gemini Speckle Imaging of Binaries among K2 Planet Hosts
The vast majority of the known exoplanets have been discovered by the Kepler mission via the transit method . The 4-arcsecond pixel size of Kepler means that light from any nearby companion or background object will be blended with that of the planetary host . The blending reduces the observed depths of
July 2018 planetary transits , making it harder to detect the planets and potentially biasing their inferred sizes . Thus , knowing the fraction of exoplanet hosts that are in binary systems is important for determining the distribution of planetary sizes as well as establishing any possible relationship between stellar multiplicity and planet formation . While there are theoretical reasons for expecting that a stellar companion may inhibit planet formation , apart from limiting the range of stable orbits , the influence of stellar multiplicity on the frequency and properties of planets is not yet fully understood .
Follow-up imaging studies of the host stars of transiting planets detected by the Kepler mission have found little or no difference in the frequency of stellar multiplicity of exoplanet hosts compared to nearby field stars , although there is some evidence that exoplanet hosts are less likely to have stellar companions within about 100 astronomical units ( AU ). Now , a team of astronomers have used high-resolution speckle imaging data from the visiting Differential Speckle Survey Instrument ( DSSI ) at both the Gemini North and South telescopes , as well as at the WIYN telescope at Kitt Peak National Observatory in Arizona , to target a sample of planetary hosts found in Kepler ’ s K2 mission . The K2
Figure 1 . Gemini / NIFS observations of Uranus . Panel A : the appearance of Uranus at 1.55 μm ( low methane absorption , showing reflection for cloud / haze at all vertical levels ), showing the position of the seven test areas used for analysis . Panel B : the appearance of Uranus at 1.62 μm ( high methane absorption , showing reflection from upper atmospheric haze only ). Panel C : reference spectrum of Uranus averaged over area “ 1 ” ( in Panel A ) near the center of the planet ’ s disk , just north of the equator . Panel D : strength of the model absorption coefficients derived over the Gemini / NIFS spectral range for conditions found at the tops of Uranus ’ s main visible clouds . ( Figure reproduced from Irwin et al ., Nature Astronomy , 2018 .)