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J/ApJ/807/170      Prograde vs retrogade motions. II. KOIs      (Holczer+, 2015)

Time variation of Kepler transits induced by stellar spots --A way to distinguish between prograde and retrograde motion. II. Application to KOIs. Holczer T., Shporer A., Mazeh T., Fabrycky D., Nachmani G., McQuillan A., Sanchis-Ojeda R., Orosz J.A., Welsh W.F., Ford E.B., Jontof-Hutter D. <Astrophys. J., 807, 170 (2015)> =2015ApJ...807..170H (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Planets ; Photometry Keywords: planetary systems; stars: activity; stars: rotation; techniques: photometric Abstract: Mazeh et al. (Paper I: 2015ApJ...800..142M) have presented an approach that can, in principle, use the derived transit timing variation (TTV) of some transiting planets observed by the Kepler mission to distinguish between the prograde and retrograde motion of their orbits with respect to their parent stars' rotation. The approach utilizes TTVs induced by spot-crossing events that occur when the planet moves across a spot on the stellar surface, looking for a correlation between the derived TTVs and the stellar brightness derivatives at the corresponding transits. This can work even in data that cannot temporally resolve the spot-crossing events themselves. Here, we apply this approach to the Kepler KOIs, identifying nine systems where the photometric spot modulation is large enough and the transit timing accurate enough to allow detection of a TTV-brightness-derivatives correlation. Of those systems, five show highly significant prograde motion (Kepler-17b, Kepler-71b, KOI-883.01, KOI-895.01, and KOI-1074.01), while no system displays retrograde motion, consistent with the suggestion that planets orbiting cool stars have prograde motion. All five systems have impact parameter 0.2≲b≲0.5, and all systems within that impact parameter range show significant correlation, except HAT-P-11b where the lack of a correlation follows its large stellar obliquity. Our search suffers from an observational bias against detection of high impact parameter cases, and the detected sample is extremely small. Nevertheless, our findings may suggest that stellar spots, or at least the larger ones, tend to be located at low stellar latitude, but not along the stellar equator, similar to the Sun. Description: We used the transit timing catalog obtained by T. Holczer et al. (2015, in preparation) publicly available at: 2600 KOIs where selected from the NASA Exoplanet Archive. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 46 224133 Light curve local slope for KOI transits table2.dat 93 2600 Statistical parameters of the transit timing variations (TTVs) and the stellar rotation of the KOIs
See also: V/133 : Kepler Input Catalog (Kepler Mission Team, 2009) J/ApJ/801/3 : Rotation periods for Q3-Q14 KOIs (Mazeh+, 2015) J/ApJ/784/45 : Kepler's multiple planet candidates. III. (Rowe+, 2014) J/ApJS/211/24 : Rotation periods of Kepler MS stars (McQuillan+, 2014) J/ApJS/210/25 : TTVs for 15 planetary pairs. II. (Xie, 2014) J/ApJS/208/16 : Kepler transit timing observations. VIII. (Mazeh+, 2013) J/ApJ/775/L11 : Stellar rotation periods for KOIs (McQuillan+, 2013) J/other/Sci/337.1511 : Kepler-47 transits (Orosz+, 2012) J/ApJ/757/18 : RVs for 16 hot Jupiter host stars (Albrecht+, 2012) J/ApJ/750/114 : Kepler TTVs. IV. 4 multiple-planet systems (Fabrycky+, 2012) J/ApJ/750/113 : Kepler TTVs. II. Confirmed multiplanet systems (Ford+, 2012) J/ApJ/749/15 : The Kepler-20 planetary system (Gautier+, 2012) J/MNRAS/421/2342 : 4 Kepler systems transit timing obs. (Steffen+, 2012) J/ApJS/197/2 : Transit timing observations from Kepler. I. (Ford+, 2011) J/ApJ/733/127 : Four transits of WASP-4b (Sanchis-Ojeda+, 2011) J/AJ/142/160 : Kepler Mission. II. 2165 eclipsing binaries (Slawson+, 2011) J/AJ/141/83 : Eclipsing binaries in Kepler first data release (Prsa+, 2011) J/A+A/527/L11 : HAT-P-6 radial velocity curve (Hebrard+, 2011) J/A+A/524/A25 : Radial Velocities on 6 exoplanet host stars (Triaud+, 2010) J/ApJ/723/L223 : Radial velocities of HAT-P-11 (Winn+, 2010) : NASA exoplanet archive Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 7 F7.2 --- KOI [1.01/5970.01] Planet KOI number (NNNN.NN) 9- 12 I4 --- n [0/2503] Transit number 14- 24 F11.6 d tt Expected mid transit time of the linear ephemeris (BJD-2454900) (1) 26- 34 F9.1 ppm/d s [-266900/297600] Derived local slope, parts per million per day 36- 42 F7.1 ppm/d e_s [3/30000] Uncertainty in derived local slope, s 44 I1 --- deg [1/6] Polynomial degree, fitted 46 I1 --- flag [0/1] 0 = ok, 1 = identified as an outlier
Note (1): Following Holczer et al. (2015, in preparation)
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 7 F7.2 --- KOI [1.01/5970.01] Planet candidate KOI number (NNNN.NN) 9- 17 F9.5 d Porb [0.5/298.5] Orbital period 19- 23 I5 --- Depth [27/97317] Transit depth in parts per million 25- 29 F5.2 d Prot [0.8/50]? Rotational period 31- 35 I5 ppm Arot [0/32015]? Rotational semi amplitude, parts per million (1) 37 I1 --- flag [0/2]? Rotational Flag (2) 39- 49 F11.2 min/d gS ? Global slope 51- 60 F10.2 min/d e_gS [0.5/1500000]? Global slope uncertainty 64 A1 --- f_(p-S) Upper limit Flag on (p-S) 66- 69 F4.1 [-] (p-S) [-7/-0]? log of the p-value of the (gS/e_gS) ratio 71- 75 F5.2 min TTV [0/15.8]? Maximum expected TTV due to spot crossing 77- 82 F6.2 min e_TTV [0.06/292.1] Median of TTV uncertainties 84- 87 I4 --- N [1/1502] Number of transit time measurements 89- 93 F5.1 --- TTVs [0/292.1]? TTV sensitivity
Note (1): Rotational semi amplitude derivation from McQuillan, Mazeh, and Aigrain (2013ApJ...775L..11M, 2014ApJS..211...24M). Note (2): Rotation Flag, based on the findings of McQuillan, Mazeh, and Aigrain (2013ApJ...775L..11M, 2014ApJS..211...24M) as follows: 0 = KOI was analyzed and no period was identified, 1 = A rotation period was detected, 2 = KOI was not analyzed.
History: From electronic version of the journal References: Mazeh et al. Paper I. 2015ApJ...800..142M
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 22-Oct-2015
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