A DISTANT MIRROR: SOLAR OSCILLATIONS OBSERVED ON NEPTUNE BY THE KEPLER K2 MISSION

• Published in: Astrophysical journal. Letters 2016-12, Vol.833 (1), p.L13-L13
• Main Authors: Gaulme, P., Rowe, J. F., Bedding, T. R., Benomar, O., Corsaro, E., Davies, G. R., Hale, S. J., Howe, R., Garcia, R. A., Huber, D., Jiménez, A., Mathur, S., Mosser, B., Appourchaux, T., Boumier, P., Jackiewicz, J., Leibacher, J., Schmider, F.-X., Hammel, H. B., Lissauer, J. J., Marley, M. S., Simon, A. A., Chaplin, W. J., Elsworth, Y., Guzik, J. A., Murphy, N., Aguirre, V. Silva
• Format: Article
• Language: English
• Subjects: Amplitudes; Astrophysics; Bison; Lunar And Planetary Science And Exploration; Neptune; Oscillations; Photometry; planets and satellites: individual (Neptune); Solar oscillations; stars: oscillations (including pulsations); Sun; Sun: helioseismology; techniques: photometric; Time series
• ISSN: 2041-8205; 2041-8213
• DOI: 10.3847/2041-8213/833/1/L13

ABSTRACT Starting in 2014 December, Kepler K2 observed Neptune continuously for 49 days at a 1 minute cadence. The goals consisted of studying its atmospheric dynamics, detecting its global acoustic oscillations, and those of the Sun, which we report on here. We present the first indirect detection of solar oscillations in intensity measurements. Beyond the remarkable technical performance, it indicates how Kepler would see a star like the Sun. The result from the global asteroseismic approach, which consists of measuring the oscillation frequency at maximum amplitude max and the mean frequency separation between mode overtones Δ , is surprising as the max measured from Neptune photometry is larger than the accepted value. Compared to the usual reference max, = 3100 Hz, the asteroseismic scaling relations therefore make the solar mass and radius appear larger by 13.8 5.8% and 4.3 1.9%, respectively. The higher max is caused by a combination of the value of max, , being larger at the time of observations than the usual reference from SOHO/VIRGO/SPM data (3160 10 Hz), and the noise level of the K2 time series, being 10 times larger than VIRGO's. The peak-bagging method provides more consistent results: despite a low signal-to-noise ratio (S/N), we model 10 overtones for degrees = 0, 1, 2. We compare the K2 data with simultaneous SOHO/VIRGO/SPM photometry and BiSON velocity measurements. The individual frequencies, widths, and amplitudes mostly match those from VIRGO and BiSON within 1 , except for the few peaks with the lowest S/N.