Coronae of stars with supersolar elemental. abundances. Peretz 1 U., Behar 1 E., Drake 2 S.A. August 18, 2015

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1 Peretz 1 U., Behar 1 E., Drake 2 S.A. 1 Department of Physics, Technion, Haifa 32000, Israel 2 USRA/CRESST & NASA/GSFC, Greenbelt, Maryland 20771, USA August 18, 2015

2 1 2 Spectra Main results FIP Bias 3 4

3 of the First Ionization Potential effect Initial FIP effect discovery. Taken from Feldman (1992). Schematic representation of the solar FIP. Meyer (1985)

4 The FIP effect - more history Newer FIP trends. Brinkman et al. (2001) Telleschi et al. (2005)

5 Motivation The physics driving the FIP effect is still unclear Much of the FIP analysis is done assuming stellar/solar within examined stars Stars with super-solar are the best candidates for observing FIP dependency in varying compositions They are also the best candidates for testing the solar assumption

6 of what we did Spectra Main results FIP Bias Measure coronal of three high metallicity stars previously not measured. Collect additional data of previously measured, but not analyzed high metallicity stars. Determine the FIP trends. Compare conclusions based on solar rather than real photospheric measurements.

7 11LMi spectra ph s 1 Å 1 cm LMi ph s 1 Å 1 cm LMi Spectra Main results FIP Bias ph s 1 Å 1 cm ph s 1 Å 1 cm Wavelength (Å) Wavelength (Å) 11LMi RGS and EPIC-pn spectra

8 ι Horologii and HR 7291 spectra Spectra Main results FIP Bias ph s 1 Å 1 cm Wavelength (Å) ph s 1 Å 1 cm Wavelength (Å) ι Horologii and HR 7291 EPIC-pn spectra

9 Abundance - Emission Measure degeneracy Spectra Main results FIP Bias Example contour plots fortifying claim absolute may be derived. Parameter: norm HR Parameter: Fe Parameter: norm Parameter: norm LMi Parameter: Fe iota Horologii Parameter: Fe

10 FIP trends Spectra Main results FIP Bias Abundance Ni Si Mg Fe alpha Centauri B C O N Ne 21 22

11 The FIP bias Spectra Main results FIP Bias FB = log ( A corona/a photo ) low ( A corona /A photo ) high

12 Summary of FIP bias measures Spectra Main results FIP Bias Table: FIP bias measures (uncertainties) Reference Object Photospheric Solar Wood LMi 0.08(0.38) 0.00(0.43) 0.08(0.44) ι Horologii 0.38(0.20) 0.31(0.18) 0.54(0.18) HR (0.41) 0.32(0.17) 0.92(0.17) τ Boo 0.42(0.75) 0.23(0.54) 0.28(0.38) α Centauri A 0.45(0.22) 0.37(0.17) 0.65(0.16) α Centauri B 0.34(0.20) 0.28(0.16) 0.42(0.18) 1 Wood & Linsky (2010), A Fe / < A C, A O, A N, A Ne >

13 The FIP Bias - continued Spectra Main results FIP Bias Wood & Linsky (2010); Wood et al. (2012); Wood & Laming (2013)

14 We measured the FIP effect in six high metallicity stars High depletion regardless of FIP Dependence on Spectral type consistent with Wood & Laming (2013) True have major implication on FIP research

15 Looking ahead More observations Highest metallicity stars Larger sample Can be done with a CCD spectrometer Aim: measuring true FIP trends normalized counts s 1 kev 1 cm Energy (kev)

16 Bibliography References Extras Brinkman, A. C. et al. 2001, A&A, 365, 324 Uri Feldman, 1992, Physica Scripta, 46, 202 Meyer, J. P. 1985, ApJS, 57, 173 Telleschi, A., Güdel, M., Briggs, K., Audard, M., Ness, J.-U., & Skinner, S. L. 2005, ApJ, 622, 653 Wood, B. E. & Linsky, J. L. 2010, ApJ, 717, 1279 Wood, B. E., Laming, J. L., & Karovska, M. 2012, ApJ, 753, 76 Wood, B.E. & Laming, J.M. 2013, ApJ, 768, 122

17 11 LMi References Extras Tables FBST More results Modeling details Table: 11 LMi Summary of Fitted Parameters Parameter EPIC-pn Value Uncertainty RGS Value Uncertainty 1σ 1σ χ DOF kt 1 [kev] kt 2 [kev] kt 3 [kev] C [solar] N [solar] O [solar] Ne [solar] Mg [solar] Si [solar] Fe [solar] fixed Ni [solar]

18 ι Horologii and HR 7291 References Extras Tables FBST More results Modeling details Table: ι Horologii and HR 7291 Summary of Fitted Parameters ι Horologii HR7291 Parameter Value Uncertainty Value Uncertainty 1σ 1σ Avg. χ Avg. DOF kt 1 [kev] kt 2 [kev] O [solar] Ne [solar] Mg [solar] Si [solar] Fe [solar]

19 Wood & Laming (2013) trend References Extras Tables FBST More results Modeling details FIP Bias ( Fe / < C, N, O, Ne > ) HR 7291 alpha Centauri A iota Horologii tau Boo 11 LMi alpha Centauri B F5 G0 G5 K0 K5 Spectral Type using the Wood & Laming (2013) FB. Grey lines represent the observed trend therein.

20 FIP trends References Extras Tables FBST More results Modeling details Abundance Ni Si Mg Fe iota Hotologii C O Ne 21 22

21 FIP trends - continued References Extras Tables FBST More results tau Boo Modeling details Abundance Ni Fe Si Mg C O N Ne 21 22

22 Detailed balance equations in detail References Extras Tables FBST More results Modeling details In general for a given ion, consider the population density in upper line j, with only electronic processes dominant: dn j dt = n e α I+1n I I+1 + S I I 1n I 1 + Q I ij ni I + Qijn I i I... + i>j i<j + A jk n k A ij n j + k>j i<j If we consider equilibrium, and invoke additional coronal assumptions: 0 = Q gj n e n g i<j A ij n j n j = Q gjn e n g i<j A ij

23 Theoretical spectrum References Extras Tables FBST More results Modeling details Define the power spectrum as the total photon density emitted per element ion per energy transition, P ij = A ij n j = n e n g Q gj = n e n H n Z n H n ion n Z n g n ion Q gj A ij k<j A kj = A ij k<j A kj Define the branching ratio, the abundance A Z, and G(T), to obtain: P ij = n e n H A Z G(T )BR ij Integrating over the volume of the source we finally get ph s.