# Summary of K2 Program GO7019

Title: Internal Mixing Processes and Angular Momentum Transport in Pulsating B-type Stars on the Main Sequence

PI: Papics, Peter I (Instituut voor Sterrenkunde)
CoIs: Briquet, Maryline; Aerts, Conny Clara; De Cat, Peter

Stellar lifetime is strongly influenced by internal mixing processes, such as core overshooting and rotation. These effects, and their precise dependency on the presence of magnetic fields or their contribution to the transport of angular momentum and chemical species are poorly known. This lack of understanding results in uncertainties on current stellar structure and evolution models of massive stars. Because many studies within modern astrophysics rely on precise predictions of these models, such as chemical enrichment of galaxies, age determination of the Universe, stellar life cycles and their effect on star and planetary system formation, dynamics within stellar clusters, etc., these uncertainties need to be resolved.

Asteroseismology is one of the few tools which allows us to study the interiors of stars by the interpretation of their non-radial oscillations. In the last years the field went through an unprecedented evolution, thanks to the immense growth in observational data and the vast improvements of asteroseismological techniques. While the nominal Kepler mission already implied a revolution in stellar physics of solar-like stars and red giants, similar achievements were not possible for massive OB stars as most of such targets were avoided in the FoV.

The frequency spectra of the pulsating beta Cep and slowly pulsating B (SPB) stars are strongly influenced by the mentioned mixing processes (e.g., Miglio et al. 2008, MNRAS, 386, 1487), which makes them ideal asteroseismic probes. By calculating theoretical pulsation models (based on stellar structure models with different input physics) we can confront the observed and theoretical frequencies and put constraints on the parameters which are either missing from, or ill-constrained in current theories. A handful of available detailed analyses show such a variety in the observed variable behaviour (e.g., Degroote et al. 2010, Nature, 464, 259; Papics et al. 2011, A&A, 528, A123; Degroote et al. 2011, A&A, 536, A82; Papics et al. 2012, A&A, 542, A55), that details in the internal physics of these stars must be different. So far, in-depth seismic modelling resulting in the determination of the overshooting parameter was achieved for only one SPB star from Kepler data (Papics et al. 2014, A&A 570, A8), bringing the total number of OB dwarfs for which this value is available to 16 (Aerts et al. 2014, arXiv:1407.6479). 

Although the amount of observational constraints is growing, the number of in-depth investigations providing precise physical parameters, and their coverage of the instability strips is too low to refine theory. K2 can have a significant contribution to extending this sample, and get us closer to the much-needed precise calibration of stellar structure and evolution models of massive stars. Furthermore, the different K2 Fields pointing towards different stellar populations of the Galaxy will show if/how internal processes and parameters depend on the presence of magnetic field, internal rotation, and stellar properties such as metallicity across the instability strips. Our final goal is to give a quantitative seismic estimate of core overshooting and internal rotational mixing using a sample of B-type stars, and obtain improvements from typically 20% to 1% relative precision in the interior physics laws for such stars. This will propagate to the very first seismic  and thus reliable  calibration of stellar evolution models in the upper part of the Hertzsprung-Russell Diagram.

We propose a few tens of targets for Fields 6 and 7 of the K2 Mission. All targets are well suited for Long Cadence, because the dominant oscillations are in the order of a day. This also explains why ground-based observations are extremely difficult for these targets.

# Targets requested by this program that have been observed (129)
EPIC ID, RA (J2000) [deg], Dec (J2000) [deg], magnitude, Investigation IDs
213379292, 288.2811584, -29.6373577, 9.191, GO7019_LC|GO7042_LC
213385540, 285.8896484, -29.6140118, 9.352, GO7019_LC|GO7042_LC|GO7030_LC
213608877, 287.2073364, -28.8412876, 10.251, GO7019_LC|GO7016_LC|GO7042_LC
213627918, 288.6520386, -28.7790451, 9.583, GO7019_LC|GO7016_LC|GO7042_LC
213786701, 281.9047852, -28.2797241, 7.498, GO7061_LC|GO7019_LC|GO7042_LC|GO7030_LC
213870506, 288.7123413, -28.0293159, 9.568, GO7019_LC|GO7016_LC|GO7042_LC
213898321, 283.3991394, -27.9479256, 10.301, GO7019_LC|GO7042_LC
213926179, 291.1257629, -27.8659439, 6.176, GO7019_LC|GO7040_LC|GO7042_LC|GO7030_LC
213931112, 286.3493958, -27.8517456, 9.621, GO7019_LC|GO7042_LC|GO7030_LC
213956594, 281.4837341, -27.7780647, 9.437, GO7019_LC|GO7042_LC
214003512, 285.1361694, -27.6451874, 8.868, GO7019_LC|GO7042_LC|GO7030_LC
214008881, 293.8869019, -27.6302128, 9.294, GO7021_LC|GO7019_LC|GO7042_LC
214081463, 282.0300903, -27.4299393, 9.353, GO7019_LC|GO7042_LC|GO7030_LC
214133870, 286.5802002, -27.2870884, 7.5, GO7061_LC|GO7019_LC|GO7042_LC|GO7030_LC
214164990, 291.4364624, -27.2023716, 9.717, GO7019_LC|GO7042_LC
214188728, 282.9858093, -27.1380997, 9.869, GO7019_LC|GO7042_LC|GO7030_LC
214208328, 281.9786072, -27.0859489, 8.51, GO7019_LC|GO7042_LC|GO7030_LC
214245114, 282.7935486, -26.9874954, 9.588, GO7019_LC|GO7016_LC|GO7042_LC
214272137, 282.0725708, -26.9164124, 9.65, GO7019_LC|GO7042_LC
214351555, 282.9806824, -26.7102413, 10.009, GO7021_LC|GO7019_LC|GO7042_LC|GO7030_LC
214354852, 286.0421753, -26.7020092, 10.372, GO7019_LC|GO7042_LC
214545782, 281.1204834, -26.2274628, 10.204, GO7019_LC|GO7042_LC|GO7030_LC
214548564, 289.7624512, -26.220417, 10.25, GO7019_LC|GO7042_LC
214594238, 286.867218, -26.1086102, 9.646, GO7019_LC|GO7042_LC
214596793, 282.4962769, -26.1024456, 10.178, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
214607980, 289.6758728, -26.0749321, 8.465, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
214853471, 287.2788696, -25.4911938, 9.818, GO7019_LC|GO7042_LC
214914668, 281.6319275, -25.3502693, 10.508, GO7021_LC|GO7019_LC|GO7016_LC|GO7042_LC
215011458, 284.7333374, -25.1335754, 8.536, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
215128511, 284.5854492, -24.8768597, 6.726, GO7019_LC|GO7042_LC|GO7030_LC
215155892, 289.5994263, -24.8173332, 9.663, GO7019_LC|GO7042_LC
215209830, 281.0137329, -24.7013607, 9.592, GO7019_LC|GO7042_LC|GO7030_LC
215230346, 287.0606689, -24.6573715, 6.403, GO7019_LC|GO7042_LC|GO7030_LC
215284586, 282.3778992, -24.5416336, 9.106, GO7019_LC|GO7042_LC|GO7030_LC
215371957, 284.2307739, -24.3574677, 9.564, GO7019_LC|GO7042_LC|GO7030_LC
215393160, 288.1095276, -24.3134747, 9.417, GO7019_LC|GO7042_LC|GO7030_LC
215441302, 281.0228577, -24.2124844, 10.328, GO7019_LC|GO7042_LC|GO7030_LC
215455606, 287.557373, -24.1825733, 10.032, GO7019_LC|GO7042_LC
215541748, 284.1757507, -24.0023613, 9.807, GO7019_LC|GO7042_LC|GO7030_LC
215549803, 288.0888367, -23.9874268, 9.679, GO7019_LC|GO7042_LC
215681930, 288.0174561, -23.7405281, 8.163, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
215706299, 285.5596619, -23.6945572, 9.059, GO7019_LC|GO7042_LC|GO7030_LC
215737361, 295.4232178, -23.6357327, 8.849, GO7019_LC|GO7030_LC
215954155, 280.9205017, -23.2306747, 8.751, GO7021_LC|GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
215975674, 287.3946228, -23.190979, 7.907, GO7019_LC|GO7042_LC|GO7030_LC
216026345, 285.3563843, -23.0971298, 11.132, GO7019_LC|GO7042_LC
216059035, 288.1242981, -23.0372162, 8.451, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
216307134, 281.7331848, -22.5834885, 9.203, GO7019_LC|GO7042_LC|GO7030_LC
216313062, 291.1587219, -22.5728207, 7.698, GO7019_LC|GO7042_LC|GO7030_LC
216314390, 283.5324402, -22.5703754, 7.733, GO7019_LC|GO7042_LC|GO7030_LC
216316812, 288.4118347, -22.5660515, 8.016, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
216404814, 283.2371216, -22.4078999, 9.084, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
216430569, 279.8300781, -22.3612347, 10.488, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
216449390, 282.8476562, -22.3277473, 8.896, GO7019_LC|GO7042_LC|GO7030_LC
216468084, 288.045105, -22.2941551, 10.442, GO7019_LC|GO7042_LC
216468609, 281.7408447, -22.2931862, 9.12, GO7019_LC|GO7042_LC|GO7030_LC
216537689, 280.6618958, -22.1701145, 8.996, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
216559119, 284.9691772, -22.1317673, 10.457, GO7021_LC|GO7019_LC|GO7042_LC
216589477, 288.6423645, -22.0775089, 9.151, GO7019_LC|GO7042_LC
216591641, 279.5647278, -22.0736465, 9.503, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
216664732, 288.4641418, -21.9440956, 9.029, GO7019_LC|GO7042_LC|GO7030_LC
216712967, 282.9269409, -21.8583851, 9.422, GO7019_LC|GO7042_LC|GO7030_LC
216893948, 290.22229, -21.5356731, 8.724, GO7021_LC|GO7019_LC|GO7042_LC|GO7030_LC
216916800, 280.1643372, -21.4947243, 8.715, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
216993160, 283.6196594, -21.3602962, 10.586, GO7019_LC|GO7042_LC|GO7030_LC
217017003, 286.8093567, -21.3183594, 10.041, GO7019_LC|GO7042_LC
217035762, 286.5872192, -21.2850113, 11.122, GO7021_LC|GO7019_LC|GO7042_LC
217100868, 286.6688843, -21.1706848, 10.236, GO7019_LC|GO7042_LC|GO7030_LC
217128767, 287.8363037, -21.1211205, 9.634, GO7019_LC|GO7042_LC
217132849, 291.032196, -21.1138248, 10.317, GO7019_LC|GO7042_LC
217248873, 283.8499756, -20.9083195, 9.912, GO7021_LC|GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
217252289, 282.9049072, -20.9023895, 9.605, GO7019_LC|GO7016_LC|GO7042_LC
217262462, 283.9143066, -20.8843651, 10.198, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
217298938, 283.4562988, -20.8196526, 10.192, GO7021_LC|GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
217307020, 287.8170776, -20.8053226, 10.108, GO7019_LC|GO7042_LC
217343386, 288.1332703, -20.7415676, 10.803, GO7019_LC|GO7042_LC
217355037, 287.10672, -20.7209625, 10.506, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
217506332, 288.7612915, -20.4555149, 10.608, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
217567172, 287.493988, -20.3491077, 10.627, GO7019_LC|GO7016_LC|GO7042_LC
217596525, 285.5740662, -20.2972908, 10.47, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
217678776, 282.2107544, -20.1535435, 8.286, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
217684883, 286.076355, -20.1425991, 8.668, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
217724184, 283.0158997, -20.0737858, 9.262, GO7019_LC|GO7016_LC|GO7042_LC
217775538, 283.1237793, -19.9830589, 8.449, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
217786992, 285.5746765, -19.9631557, 11.078, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
217834817, 283.5323792, -19.8795223, 10.768, GO7021_LC|GO7019_LC|GO7042_LC
217843647, 291.7608032, -19.8637867, 10.396, GO7019_LC|GO7042_LC
217843767, 283.6971436, -19.8635731, 9.553, GO7019_LC|GO7042_LC
217846683, 283.6343079, -19.8584995, 10.214, GO7019_LC|GO7042_LC|GO7030_LC
217890054, 283.8253784, -19.7822628, 10.087, GO7019_LC|GO7042_LC
217929186, 284.151001, -19.7128906, 10.021, GO7019_LC|GO7042_LC|GO7030_LC
217932889, 290.2782288, -19.7064133, 10.383, GO7019_LC|GO7042_LC
217960451, 290.8502197, -19.6575203, 10.236, GO7019_LC|GO7016_LC|GO7042_LC
217960473, 282.6741028, -19.6574783, 10.174, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
217988375, 283.6013184, -19.6083927, 10.196, GO7019_LC|GO7042_LC
218026301, 287.1502686, -19.5412807, 10.789, GO7019_LC|GO7042_LC
218056934, 288.269043, -19.4873257, 8.846, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
218064450, 289.881897, -19.4740143, 9.691, GO7019_LC|GO7042_LC
218080954, 283.8191223, -19.4448357, 10.16, GO7019_LC|GO7042_LC
218092142, 288.487793, -19.425108, 10.223, GO7019_LC|GO7042_LC
218098335, 283.5845337, -19.4140816, 10.455, GO7019_LC
218155470, 285.4362488, -19.3121338, 9.824, GO7019_LC|GO7030_LC
218222000, 285.6408691, -19.1920013, 10.197, GO7019_LC|GO7042_LC
218337072, 282.854248, -18.9852753, 10.518, GO7019_LC
218364652, 288.4902039, -18.9352856, 10.1, GO7019_LC|GO7042_LC|GO7030_LC
218437326, 282.2422485, -18.8037262, 10.275, GO7019_LC|GO7042_LC|GO7030_LC
218480404, 286.9073486, -18.7262535, 9.784, GO7019_LC|GO7042_LC
218609954, 287.2879639, -18.4888306, 9.065, GO7019_LC|GO7042_LC|GO7030_LC
218724323, 287.8194885, -18.2745705, 10.0, GO7019_LC|GO7042_LC
218744693, 293.0953064, -18.2359104, 10.173, GO7019_LC|GO7042_LC
218788928, 286.9941711, -18.1517181, 10.838, GO7019_LC|GO7042_LC
218821114, 282.4593506, -18.0905647, 9.201, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
218839905, 282.091217, -18.0545769, 9.923, GO7019_LC|GO7042_LC|GO7030_LC
218894831, 283.5369263, -17.9514027, 10.667, GO7019_LC|GO7042_LC
218901862, 282.5188293, -17.9382973, 8.383, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
218933229, 284.8666077, -17.8803902, 8.101, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
218974586, 285.4957275, -17.7962494, 10.868, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
218991256, 286.0362854, -17.7606945, 8.782, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
219069169, 285.0545654, -17.5932884, 9.592, GO7019_LC|GO7042_LC|GO7030_LC
219188112, 286.1953125, -17.3320694, 8.652, GO7019_LC|GO7016_LC|GO7042_LC|GO7030_LC
219217553, 289.4332886, -17.2660408, 10.189, GO7019_LC|GO7016_LC|GO7042_LC
219233421, 292.9236755, -17.2302742, 9.405, GO7019_LC|GO7042_LC
219267976, 286.7484131, -17.1516628, 11.309, GO7030_LC|GO7019_LC|GO7016_LC|GO7042_LC
219299875, 289.594574, -17.0782547, 9.044, GO7019_LC|GO7016_LC|GO7042_LC
219332164, 285.6906128, -17.0034714, 9.289, GO7021_LC|GO7019_LC|GO7042_LC|GO7030_LC
219335186, 288.2252808, -16.9963684, 9.383, GO7019_LC|GO7042_LC
219353144, 289.8475647, -16.9545574, 9.725, GO7061_LC|GO7019_LC|GO7042_LC
219511589, 289.0819092, -16.5692959, 8.312, GO7035_LC|GO7019_LC|GO7016_LC|GO7042_LC|GO7056_LC|GO7030_LC|GO7035_SC
219590819, 289.460968, -16.3632889, 9.725, GO7019_LC|GO7042_LC