Science

Image Credit: NASA Ames/W. Stenzel

Science from K2

K2 is an active, community-driven mission with a variety of scientific results that relate to the discovery of transiting planets around bright, nearby stars, star clusters, extragalactic astrophysics, supernovae studies, solar system objects, and more. For example, K2 has already discovered over 20 transiting planets with hundreds more candidates awaiting confirmation. K2 has also provided unparalleled photometry of Neptune and asteroids in the solar system. Additional information about the mission, including publications using K2 data, the previous and upcoming Campaigns, and approved targets and programs can be found on the following pages.

• Overview of the K2 mission
• Publications using K2 data
• K2 Campaign fields
• K2 technical information
• K2 approved targets and programs
• K2 Campaign 9 microlensing experiment

The image below highlights some of the science that has been or will be conducted with data from K2.

Image Credit: NASA Ames/W. Stenzel

Science from Kepler

With over four years of continuous monitoring of over 150,000 stars in the Cygnus-Lyra region, Kepler has produced and still continues to produce myriad scientific results. To date, Kepler has discovered over 4,600 planet candidates, many of which have already been confirmed or validated. These planets are highlighted in the image below. Kepler data has also revealed insights into eclipsing binary systems, asteroseismology, gyrochronology, supernovae, and more. A comprehensive list of Kepler publications can be found here.

Image Credit: NASA Ames/W. Stenzel

Working groups

The Kepler Project fosters self-governing working groups of community scientists to advance and recommend upon aspects of primary mission science. Working groups also collaborate on science projects that are complementary to the primary science goals. Several of these groups are still active. All the working groups are described briefly below.

• Threshold Crossing Event Review Team (TCERT)
  POC: Michael Haas, NASA Ames Research Center
  
  TCERT is primarily responsible for reviewing and dispositioning the Threshold Crossing Events (TCEs) identified by the Kepler Pipeline. A TCE is a statistically significant transit signal detected by Kepler's analysis pipeline. During the initial review process, TCEs that indicate a planetary-size companion are declared Kepler Objects of Interest (KOIs) and subjected to additional tests and more rigorous scrutiny. Once this in-depth analysis and evaluation is complete, each KOI will be dispositioned as a planetary candidate or false positive. These results are delivered on a regular basis to NExScI for public release through their Exoplanet Archive.

• Follow-up Observing Program (FOP)
  POC: David Ciardi, NASA Exoplanet Science Institute
  
  The scientific goals of the Kepler Extended Mission Follow-up Observation Program (XMFOP) are to confirm and validate the planetary nature of the Kepler Objects of Interest (KOIs) via the determination of stellar parameters, radial velocity curves, and stellar blends. Besides yielding exoplanet confirmations and characterizations, the work results in more accurate properties of the KOI host stars and, consequently, the planet candidates they harbor. The work also yields a better understanding of the overall reliability of the KOI catalog. The XMFOP performs the following duties in support of Kepler's scientific goals:

  • Spectroscopic observations for the purpose of determining stellar properties.
  • Spectroscopic observations for the purpose of identifying stellar companions and/or placing limits on the presence of such companions.
  • High-precision radial velocity for a limited sample of relatively small exoplanet candidates to determine their masses and other orbital properties.
  • High spatial resolution imaging for the purpose of detecting line-of-sight and/or physically associated stars in the photometric aperture and/or placing constraints on the presence of such blends.
  • Other supporting observations as opportunities arise (e.g. Spitzer, HST, etc).

• False Positive Working Group (FP)
  POC: Steve Bryson, NASA Ames Research Center
  
  There are instrumental and astrophysical signals that mimic planetary transits in the Kepler flux time series. The Kepler False Positive Working Group is oriented towards identifying such astrophysical and instrumental false positives (FP) among the Kepler Objects of Interest (KOIs). The mandate of the FP working group is to:

  • Identify/confirm false positive KOIs via analysis of Kepler data.
  • Track and incorporate false positive identifications from other observations from both the Kepler community follow up program and other sources.
  • Identify sources of FP signals and recommend appropriate action (such as addition to the eclipsing binary catalog).
  • Deliver lists of identified false positives to the Kepler archives at NExScI and MAST.
  • Maintain the quality and integrity of the false positive flags on the Kepler Exoplanet Archive (NexScI), including regular re-vetting using additional data as appropriate.
    

• Star Properties Working Group (STAR)
  POC: Daniel Huber, University of Hawaii
  POC: Jaymie Matthews, University of British Columbia
  POC: Marc Pinsonneault, Ohio State University
  
  Fundamental stellar properties are required for the determination of planet properties and for quantifying the sensitivity biases that affect the calculation of planet occurrence rates. The Star Properties working group acts as an advisory body for issues related to stellar characterization and the determination of fundamental stellar properties. Specific topics include:

  • Assess the systematic errors in the stellar properties provided in the Kepler Input Catalog.
  • Provide recommendations to the project on the best strategy for adopting properties of all Kepler target stars and deliver regular updates of star properties to the Kepler Science Office for use as input to the pipeline analysis software and the light curve modeling that leads to planet properties.
  • Provide recommendations to the Kepler project on the optimization of follow-up resources for the goal of characterizing the Kepler target stars. Recommendations are communicated to the Follow-up Program (FOP) Coordinator before the start of the Kepler observing season.

• Kepler Asteroseismic Science Consortium (KASC)
  POC: Ron Gilliland, Penn State
  
  The Kepler Asteroseismic Science Consortium (KASC) is a large and unique scientific collaboration, around which the asteroseismic analysis of Kepler data has been arranged since the beginning of the Mission. KASC is divided into ten working groups, each focusing on the analysis of different classes of pulsating stars.

• Transit Timing Variations and Multiple-Body Working Group (TTV)
  POC: Jack Lissauer, NASA Ames Research Center
  
  The scientific goals of the TTV working group are to characterize planetary systems, measure the distributions of important system parameters using the Kepler data, and estimate important quantities pertaining to Earth-size planets. The detection and analysis of transit timing variations is a means of confirming the planetary nature of a transiting object identified in Kepler data. Confirmation of Kepler's exoplanet candidates ultimately leads to higher catalog reliability and/or a quantitative assessment of that reliability. Full dynamical modeling of transit timing variations yields planet mass which, together with the planet radius produced by light curve modeling, yields planet density. The density distribution of small planets is of interest in understanding what fraction of Kepler's Earth-size planets are rocky. The TTV group also works to understand the sample statistics and architectures of multiple planet systems.

• Eclipsing Binary Working Group (EB)
  POC: Andrej Prsa, Villanova University
  
  The Eclipsing Binary Working Group is tasked with the following goals, in the order of priority:

  • Maintain the catalog of eclipsing binaries in the Kepler field, including their ephemerides, the derived properties via automated methods, the geometric properties (eclipse widths, depths and separations), and any additional signal (ellipsoidal variability, eclipse timing variations, tertiary events, multiple periodicities); to find statistical properties of EBs: spatial distributions, multiplicity and orbital properties (eccentricity distributions);
  • Determine the occurrence rate of false positives in the KOI catalog, including background (faint) eclipsing binaries that contaminate the target's photometric aperture as well as foreground (bright) eclipsing binaries that bleed into the target’s aperture; and
  • Detect, validate and analyze circumstellar and circumbinary planets via tertiary events and eclipse timing variations.

Guest Observer program

In addition to its prime mission, Kepler offered a Guest Observer (GO) program that allowed the community to propose observations addressing any area of planetary, stellar or extragalactic astrophysics. Approved programs from the four Kepler GO cycles are listed below.

Cycle 1 (2009)

Cycle 2 (2010)

Cycle 3 (2011)

Cycle 4 (2012)

Participating Scientist program

The Kepler Participating Scientist Program (PSP) was designed to fund community investigations that advance the goals of the Kepler Mission. Participating Scientists pursue data processing and analysis tasks, exoplanet candidate follow-up observations, completeness and reliability studies, characterization of the stellar target sample, and other activities. Approved PSPs are listed below.

Cycle 1 (2008)

Cycle 2 (2011)

Cycle 3 (2013)