1,690 research outputs found
Non-detection of Contamination by Stellar Activity in the Spitzer Transit Light Curves of TRAPPIST-1
We apply the transit light curve self-contamination technique of Morris et
al. (2018) to search for the effect of stellar activity on the transits of the
ultracool dwarf TRAPPIST-1 with 2018 Spitzer photometry. The self-contamination
method fits the transit light curves of planets orbiting spotted stars,
allowing the host star to be a source of contaminating positive or negative
flux which influences the transit depths but not the ingress/egress durations.
We find that none of the planets show statistically significant evidence for
self-contamination by bright or dark regions of the stellar photosphere.
However, we show that small-scale magnetic activity, analogous in size to the
smallest sunspots, could still be lurking in the transit photometry undetected.Comment: Accepted for publication in ApJ
Chromospheric Activity of HAT-P-11: an Unusually Active Planet-Hosting K Star
Kepler photometry of the hot Neptune host star HAT-P-11 suggests that its
spot latitude distribution is comparable to the Sun's near solar maximum. We
search for evidence of an activity cycle in the CaII H & K chromospheric
emission -index with archival Keck/HIRES spectra and observations from the
echelle spectrograph on the ARC 3.5 m Telescope at APO. The chromospheric
emission of HAT-P-11 is consistent with a year activity cycle,
which plateaued near maximum during the Kepler mission. In the cycle that we
observed, the star seemed to spend more time near active maximum than minimum.
We compare the normalized chromospheric emission index of
HAT-P-11 with other stars. HAT-P-11 has unusually strong chromospheric emission
compared to planet-hosting stars of similar effective temperature and rotation
period, perhaps due to tides raised by its planet.Comment: 16 pages, 8 figures; accepted to the Astrophysical Journa
- …