Photometric observation of HAT-P-16b in the near-UV

Abstract

We present the first primary transit light curve of the hot Jupiter HAT-P-16b in the near-UV photometric band. We observed this object on December 29,2012 in order to update the transit ephemeris, constrain its planetary parameters and search for magnetic field interference. Vidotto et al. (2011a) postulate that the magnetic field of HAT-P-16b can be constrained if its near-UV light curve shows an early ingress compared to its optical light curve, while its egress remains unchanged. However, we did not detect an early ingress in our night of observing when using a cadence of 60 seconds and an average photometric precision of 2.26mmag. We find a near-UV planetary radius of Rp=1.274+-0.057RJup which is consistent with its near-IR radius of Rp=1.289+-0.066RJup (Buchhave et al., 2010). We developed an automated reduction pipeline and modeling package to process our data. The data reduction package synthesizes a set of IRAF scripts to calibrate images and perform aperture photometry. The modeling package utilizes the Levenberg-Marquardt minimization algorithm to find a least-squares best fit and a differential evolution Markov Chain Monte Carlo algorithm to find the best fit to the light curve. To constrain the red noise in both fitting models we use the residual permutation (rosary bead) method and time-averaging method.Comment: 9 pages, 3 figures, New Data Reduction Program and Modeling Package. arXiv admin note: text overlap with arXiv:1211.489

Ground-based near-UV observations of 15 transiting exoplanets: constraints on their atmospheres and no evidence for asymmetrical transits

“…The data points of all our transits are available in electronic form (see Table 3). For all the transits, the OoT baselines have a photometric root mean squared (rms) value between 1.23 and 6.22 mmag, consistent with previous high S/N transit photometry using the Mont4k on the 1.55-m Kuiper telescope (Dittmann et al 2009b(Dittmann et al , 2012Scuderi et al 2010;Teske et al 2013;Turner et al 2013;Pearson et al 2014;Zellem et al 2015). …”

“…Both these properties are well within reach for ground-based metre-sized telescopes (e.g. Copperwheat et al 2013;Turner et al 2013;Pearson et al 2014), like the Steward Observatory 1.55-m Kuiper Telescope used for the near-UV observations in this study. Additionally, Nichols et al (2015) find that summing over the entire NUV band (253.9-281.1 nm) on Hubble Space Telescope (HST) still resulted in an early ingress, which they attributed to a blend of thousands of lines of metals (e.g.…”

“…Spectroscopic and photometric studies have confirmed and improved upon the discovery values (Husnoo et al 2012;Ciceri et al 2013;Pearson et al 2014;Sada & Ramón-Fox 2016). It was found through Rossiter-McLaughlin observations (Moutou et al 2011) that HAT-P-16b's projected spin-orbit angle of λ = −10 • ± 16 • is aligned with the stellar spin axis.…”

“…To find the best fit to the light curves, we develop a modelling package called the EXOplanet MOdeling Package (EXOMOP; Pearson et al 2014) …”

“…There are five exoplanets (55 Cnc b, GJ 436b, HD 189733b, HD 209458b, WASP12b) where asymmetries in their light curves are observed (VidalMadjar et al 2003(VidalMadjar et al , 2004(VidalMadjar et al , 2008(VidalMadjar et al , 2013Ben-Jaffel 2007Fossati et al 2010;Ehrenreich et al 2012Ehrenreich et al , 2015Haswell et al 2012;BenJaffel & Ballester 2013;Kulow et al 2014;Nichols et al 2015). For the symmetric transits, nine hot Jupiters (HAT-P-1b, HAT-P-12b, WASP43b, are observed to have a constant planetary radii from near-UV to optical wavelengths Turner et al 2013;Bento et al 2014;Nikolov et al 2014;Pearson, Turner & Sagan 2014;Mallonn et al 2015;Ricci et al 2015;Sing et al 2016). Additionally, 11 exoplanets with symmetric light curves (GJ 3470b, HD 189733b, HD 209458b, HAT-P-5b, HATP12b, WASP-6b, WASP-12b, WASP-17b, WASP-31b, WASP-39b, XO-2b) are observed to have a larger near-UV radii than optical wavelengths Sing et al 2008Sing et al , 2011Sing et al , 2013Sing et al , 2015Sing et al , 2016Southworth et al 2012b;Nascimbeni et al 2013;Zellem et al 2015).…”