# Summary of K2 Program GO13101

Title: A K2 Survey of Hot Massive Stars during Campaigns C11 and C13

PI: Gies, Douglas Russell (Georgia State University)
CoIs: 

Introduction:
The NASA Kepler mission was a huge success for exoplanet detection and stellar astronomy. We obtained magnificent 
time series data that have led to remarkable new studies especially in the areas of asteroseismology, stellar 
rotational modulation, and binary and multiple stars. However, the Kepler field of view was selected away from the 
Galactic plane to avoid problems with blending in the crowded star fields close to the plane. Because the massive stars 
are generally young and form in the Galactic plane, the selection of a FOV away from the plane meant that very few massive 
stars were measured by Kepler (no O-type stars, for example). Now with K2 we have the opportunity to remedy the situation 
and follow the light curves of a significant sample of massive stars. First observations occurred during campaigns 
C0, C4, and C7, and now in C11 and C13, the K2 FOV is again located close to the galactic plane, so that massive star
targets are accessible.  This proposal describes the massive star sample and the kinds of scientific investigations that 
would be possible through such K2 photometric observations.

Sample:
I selected stars from the "Catalogue of Stellar Spectral Classifications" (Skiff, 2009-2014) that is available from
CDS Vizier.  A total of 176 and 27 targets were selected that are within the nominal boresight coordinates for C11 and 
C13, respectively, and confirmed to fall on the CCD detectors using the K2fov program. These stars have magnitudes in the
range V = 8 to 12.  They comprise a diverse collection of young stars, mainly of spectral types O and B and spanning 
all luminosity classes. The group includes a number of the rapidly rotating Be stars that eject gas into a circumstellar 
disk.  All these stars are ideal long cadence targets for continuous temporal coverage during the C11 and C13 campaigns, 
and we plan to obtain contemporaneous spectroscopy of them.

Eclipsing Binaries and Exoplanets:
Massive stars are rare, and consequently there are relatively few with well-established masses from combined spectroscopic 
and photometric analysis (Torres et al. 2010, A&ARv, 18, 67 note only four eclipsing systems containing O-type stars in 
their compendium of accurate eclipsing binary results).  Consequently, the identification of new eclipsing binaries 
would offer us important new targets for the determination of fundamental parameters. In addition, massive stars are 
often found in multiple systems, and the survey would help determine the incidence of massive stars with eclipsing 
binary companions. There are several known exoplanets that orbit host B-type stars, and the C11 and C13 campaigns offer
a superb opportunity to search for transiting planets that managed to form in the energetic radiation fields of the 
hot host stars.

Asteroseismology:
The early-type pulsating stars include the beta Cep class (p-mode), slowly pulsating B stars (g-mode), and periodically 
variable B and A-type supergiants. These pulsations are important probes of stellar interiors. The K2 sample will 
determine the incidence of pulsations and how multiple-mode beating may play a role in the gas ejection processes that 
lead to disk formation in the emission line Be stars.

Magnetic Fields and Rotational Modulation:
Massive stars generally have convective cores and radiative envelopes that are not usually associated with magnetic 
dynamos and field generation. Nevertheless, sensitive polarimetric surveys like the MiMeS project have led to the 
detection of magnetic fields in about 10% of the OB-stars. In these cases, the magnetic field can produce spots that 
introduce a rotational modulation in the light curve. The K2 survey will help determine the frequency of such 
rotational modulations and will provide a sample large enough to study the kinds of stellar parameters that are 
associated with magnetic fields.

# Targets requested by this program that have been observed (25)
EPIC ID, RA (J2000) [deg], Dec (J2000) [deg], magnitude, Investigation IDs
246800994, 73.449516, 15.752878, 9.583, GO13122_LC|GO13101_LC|GO13038_LC|GO13052_LC
246820783, 68.357293, 15.960932, 9.108, GO13071_LC|GO13122_LC|GO13101_LC|GO13024_LC|GO13052_LC|GO13127_LC
246968035, 70.385958, 17.412931, 8.828, GO13071_LC|GO13122_LC|GO13101_LC|GO13024_LC|GO13052_LC
247106666, 69.629404, 18.733741, 8.771, GO13122_LC|GO13002_LC|GO13101_LC|GO13095_LC|GO13052_LC
247136661, 71.297162, 19.019829, 10.103, GO13071_LC|GO13122_LC|GO13101_LC|GO13077_LC|GO13036_LC|GO13052_LC
247144563, 71.527839, 19.095106, 11.079, GO13122_LC|GO13101_LC|GO13077_LC|GO13052_LC
247147343, 71.501861, 19.121894, 9.645, GO13122_LC|GO13101_LC|GO13077_LC|GO13052_LC|GO13127_LC
247147476, 71.313996, 19.123262, 9.985, GO13122_LC|GO13101_LC|GO13024_LC|GO13077_LC|GO13052_LC|GO13127_LC
247148818, 71.28398, 19.136015, 10.065, GO13122_LC|GO13101_LC|GO13024_LC|GO13077_LC|GO13052_LC
247153152, 71.492121, 19.177505, 9.289, GO13122_LC|GO13101_LC|GO13056_LC|GO13077_LC|GO13052_LC|GO13127_LC
247153504, 71.483123, 19.180984, 8.975, GO13122_LC|GO13002_LC|GO13101_LC|GO13077_LC|GO13036_LC|GO13052_LC
247156683, 71.324858, 19.211463, 10.187, GO13122_LC|GO13101_LC|GO13024_LC|GO13077_LC|GO13052_LC
247164195, 71.45274, 19.282263, 9.327, GO13113_LC|GO13122_LC|GO13101_LC|GO13077_LC|GO13052_LC|GO13127_LC
247169098, 71.394528, 19.328305, 8.671, GO13112_LC|GO13071_LC|GO13122_LC|GO13101_LC|GO13024_LC|GO13059_LC|GO13077_LC|GO13082_LC|GO13052_LC|GO13127_LC
247253514, 80.718034, 20.127981, 10.191, GO13122_LC|GO13101_LC
247368219, 76.705673, 21.138358, 11.427, GO13122_LC|GO13101_LC|GO13082_LC|GO13052_LC|GO13127_LC
247559520, 69.806436, 22.652252, 8.946, GO13122_LC|GO13101_LC|GO13052_LC|GO13127_LC
247587084, 75.197544, 22.864654, 10.414, GO13122_LC|GO13101_LC|GO13038_LC|GO13052_LC
247664011, 68.582854, 23.447141, 9.946, GO13117_LC|GO13049_LC|GO13071_LC|GO13122_LC|GO13101_LC|GO13052_LC
247732582, 70.24527, 23.939798, 9.399, GO13071_LC|GO13122_LC|GO13101_LC|GO13024_LC|GO13052_LC
247745384, 75.566223, 24.029163, 9.144, GO13112_LC|GO13071_LC|GO13122_LC|GO13002_LC|GO13101_LC|GO13095_LC|GO13059_LC|GO13082_LC|GO13052_LC|GO13127_LC
247774959, 68.471635, 24.235579, 12.072, GO13071_LC|GO13122_LC|GO13101_LC|GO13052_LC|GO13127_LC
247974919, 74.516732, 25.621777, 9.292, GO13071_LC|GO13122_LC|GO13101_LC|GO13052_LC
248014510, 70.352997, 25.913453, 9.896, GO13123_LC|GO13016_LC|GO13101_LC|GO13052_LC
248224646, 74.205702, 27.718509, 12.057, GO13123_LC|GO13071_LC|GO13122_LC|GO13101_LC|GO13082_LC