Yuhan Yao Mentor: Michael Meyer Defense @ KIAA-PKU June 8 2018 Primordial Disk Frequencies Around Young Stars in NGC1333, IC 348, and the Orion A Molecular Cluster 

Yuhan Yao Mentor: Michael Meyer Defense @ KIAA-PKU June 8 2018 Primordial Disk Frequencies Around Young Stars in NGC1333, IC 348, and the Orion A Molecular Cluster 

Teff & logg derived by Cottaar et al. (2014) Accurate logg for young stars ! Primordial Disk Frequencies Around Young Stars in NGC1333, IC 348, and the Orion A Molecular Cluster Observed by the INfrared Spectra of Young Nebulous Clusters (IN-SYNC) program, part of APOGEE 

ØDisk Frequency vs. stellar age (indicated by logg) ØDisk Frequency vs. stellar mass (indicated by Teff ) In each cluster: Observed by the INfrared Spectra of Young Nebulous Clusters (IN-SYNC) program, part of APOGEE Primordial Disk Frequencies Around Young Stars in NGC1333, IC 348, and the Orion A Molecular Cluster Teff & logg derived by Cottaar et al. (2014) Accurate logg for young stars ! 

Gas-rich disk lifetime Gas giant planet formation timescale Disks lives shorter around higher mass stars. Disk mass increases with stellar mass. We need disk lifetime to constrain planet formation theories. 

Sources in IC 348 Red: observed, used Mostly low mass stars. Blue: observed, not used Eg: only use 2700K

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Red vs. Red+Blue+Grey -- Observed and used -- Observed and used + Observed but not used + Not observed Representative sample? 2D K-S test: 

Spitzer (IRAC) 3.6-8.0 μm Photosphere + Disk Only Photosphere Excess color De-reddened color Photospheric color 

= Select sources: 

Disk frequency vs. stellar mass ü M > 1Msun : disks around lower mass stars last longer. ü 0.2Msun < M < 0.7Msun : no significant dependence Result 1 

Disk frequency vs. stellar mass Result 1 ü M > 1Msun : disks around lower mass stars last longer. ü 0.2Msun < M < 0.7Msun : no significant dependence 

Disk frequency vs. stellar age In IC 348 Higher disk frequency around younger stars. Younger Older Stars with primordial disk Stars without primordial disk Result 2 

In NGC 1333 Disk frequency vs. stellar age Younger Older In Orion A Result 2 

Take-home messages: Thank you to: Michael Meyer, Kevin Covey, Jonathan Tan; Michiel Cottaar, Janathan Foster; Greg Herczeg; Lee Hartmann, Nuria Calvet, Jesus Hernández, Mark Pecaut. • Primordial disks around early-type stars evolve faster than that around late-type stars. • Using log(g) as an age indicator, in 3 single clusters, we show younger stars has higher disk frequency. 

Whole cluster population: red+blue+grey? (1) How many stars not in the cluster are included in the grey? Contamination from background stars (old, reddened); Contamination from foreground stars (less reddened) – Galactic star count model: <10% (2) How many stars in the cluster are not included in the grey? Proto-stars: removed. 

Red vs. Red+Blue+Grey -- Observed and used -- Observed and used + Observed but not used + Not observed Representative sample? 2D K-S test: white contour: KS test p-value=0.2 0.2—1.5Msun (AJ <4.0) 

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A drop of disk frequency for the lowest mass stars? Lada et al. (2006) See also Hernández et al. (2007), Dahm & Hillenbrand (2007), Fang et al. (2013). 

ü M > 1Msun : disks around lower mass stars last longer. ü 0.2Msun < M < 0.7Msun : no significant dependence Disk frequency vs. stellar mass Result 1 

Fiducial Disk SEDs (Models from Robitaille et al. 2006) 2.0 Msun 1.0 Msun 0.3 Msun 0.1 Msun For M > 0.1Msun , no bias longer than 4μm. 

Black lines: Expected from fiducial models Colored lines: Typical value of In each cluster 

Remove proto-stars: Primordial disks: sources with excess at [4.5] Compile a list of intermediate mass stars: Allen et al. (2004) Luhman et al. (2016), Da Rio et al. (2012), Hsu et al. (2012, 2013)