TRANSITING the SUN. II. the IMPACT of STELLAR ACTIVITY on Lyα TRANSITS

Research output: Contribution to journalArticle

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Abstract

High-energy observations of the Sun provide an opportunity to test the limits of our ability to accurately measure the properties of transiting exoplanets in the presence of stellar activity. Here we insert the transit of a hot Jupiter into continuous disk integrated data of the Sun in Lyα from NASA's Solar Dynamics Observatory/Eve instrument to assess the impact of stellar activity on the measured planet-to-star radius ratio (Rp/R). In 75% of our simulated light curves, we measure the correct radius ratio; however, incorrect values can be measured if there is significant short-term variability in the light curve. The maximum measured value of Rp/R is 50% larger than the input value, which is much smaller than the large Lyα transit depths that have been reported in the literature, suggesting that for stars with activity levels comparable to the Sun, stellar activity alone cannot account for these deep transits. We ran simulations without a transit and found that stellar activity cannot mimic the Lyα transit of 55 Cancari b, strengthening the conclusion that this planet has a partially transiting exopshere. We were able to compare our simulations to more active stars by artificially increasing the variability in the Solar Lyα light curve. In the higher variability data, the largest value of Rp/R we measured is

Original languageEnglish (US)
Article number81
JournalAstrophysical Journal
Volume817
Issue number1
DOIs
StatePublished - Jan 20 2016

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stellar activity
transit
light curve
planet
sun
stars
planets
Jupiter
simulation
observatory
helioseismology
radii
extrasolar planets
inserts
Jupiter (planet)
observatories
energy

Keywords

  • planets and satellites: atmospheres
  • stars: activity
  • starspots

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

TRANSITING the SUN. II. the IMPACT of STELLAR ACTIVITY on Lyα TRANSITS. / Llama, J.; Shkolnik, Evgenya.

In: Astrophysical Journal, Vol. 817, No. 1, 81, 20.01.2016.

Research output: Contribution to journalArticle

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