K2 Observations of Open Clusters Ann Marie Cody NPP fellow at NASA Ames November 2, 2015

K2 Observations of Open Clusters

Ann Marie CodyNPP fellow at NASA Ames

November 2, 2015

Acknowledgments

•Ames collaborators: Steve Howell, Tom Barclay, Fergal Mullally, Susan Thompson, Geert Barentsen, Jason Rowe, student interns: Bryan Mann, Shishir Dholakia, Shashank Dholakia

•External collaborators: Lynne Hillenbrand, Trevor David, John Stauffer, Luisa Rebull, Kevin Covey, Adam Kraus, Michael Ireland, Stephanie Douglas, Suzanne Aigrain

K2 is ideally suited to monitor star clusters

Large field of view

High precision

Long time baseline

Continuous time series

Bright, nearby targets – great for follow-up

M35

Ground vs. K2

A. Vanderburg

Nardiello et al. (2015)

K2 is Contributing Enormously to Young Star Science

Taurus!!(300+ knownmembers)

K2 has a number of photometric pipelines

Official K2 pipeline: Light curves for Campaigns 3, 4, 5 with PDC detrending

A. Vanderburg pipeline: Light curves for Campaigns 0-4 with SFF detrending

Other approaches- C. Huang et al. (2015); Libralato et al. (2015); S. Aigrain in prep.

My pipeline: operates on both regular and superstamp images

Superstamp Photometry: M35

Superstamp WCS solution • Track X,Y movement of individual sources•Measure fluxes with range of moving circular apertures• Decorrelate flux vs. X,Y position

Decorrelate flux vs. X,Y position

Star clusters in the time domain: Science

Eclipsing binaries

Starspot properties and stellar rotation

Exploration of accretion and disk- related variability

Search for young planets

~50 EBs in the M35 Superstamp …but which are cluster members?

M35 Candidates

Field stars Bouy et al. (2015)

Eclipsing Binaries are Yielding Clues to Early Stellar Evolution

David, Hillenbrand, Cody+ subm.

David poster


Eclipsing binaries




K2 reveals spot evolution and/or differential rotation

M35 M35

USco USco

Pleiades Pleiades

Hyades Hyades

K2 reveals spot evolution and differential rotation

Can be difficult to differentiate the two phenomena (Aigrain et al. 2015)

~20-30% of intermediate age stars show multiple light curve frequencies

Spot evolution appears on ~week timescales, if at all.

Currently comparing long-term spot behavior on the pre main sequence vs. in older clusters. Mass dependence unclear.

Rebull poster

The mass dependence of rotation at young ages

Covey poster


Eclipsing binaries




Hartmann 1999

The space based photometry revolution on young stars

CoRoT:NGC 2264MOST:

Taurus-Auriga/ Lupus/TW Hya

K2:Sco-Cen/

ρ Oph/Lagoon/Taurus?

• Sub-1% precision• 20-80 days of continuous photometric monitoring

A Zoo of Young Star Light Curves

Stochasticstars

Quasi-periodicstars

Purelyperiodic

Flux Asymmetry

Stochasticity

Light Curve Classification Scheme

Eclipsingbinaries

Bursters

Dippers

Cody+ 2014

Classes can now be selected statistically!

Cody et al. 2014

~20-30%: Quasi-periodic flux dips:Circumstellar dust obscuration

New classes of young star behavior!“Bursters”

[Embargoed slide.]

Bursters display a spatial spread on the sky


Eclipsing binaries




Many False Positives to Sort Through!

A candidate – but unclear whether it is a cluster member

Found by high school students Shashank &

Shishir Dholakia!

Summary

K2 is an excellent platform for photometric monitoring of young to intermediate age star clusters.

The resulting time series are being used to contrain stellar parameters, understand angular momentum evolution, as well as magnetic spot properties.

More cluster data to come!

By the end of the mission, we may have a significant enough sample to constraint planet occurrence rates at young ages.

Documents

K2 Observations of Open Clusters Ann Marie Cody NPP fellow at NASA Ames November 2, 2015