changes in mean global physical parameters of blazhko rr lyrae stars derived from multicolour...
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Changes in Mean GlobalChanges in Mean GlobalPhysical Parameters ofPhysical Parameters ofBlazhko RR Lyrae starsBlazhko RR Lyrae stars
derived fromderived frommulticolour photometrymulticolour photometry
Ádám SódorÁdám SódorKonkoly ObservatoryKonkoly ObservatoryStellar Pulsation Meeting,Stellar Pulsation Meeting,Santa Fe – June 2, 2009Santa Fe – June 2, 2009
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TelescopeThe Inverse Photometric Baade–Wesselink Method
(Sódor, Jurcsik & Szeidl, 2009, MNRAS, 394, 261)
Input:– multicolour light curves [B(), V(), IC() or V(), IC(),
where denotes pulsation phase],– metallicity,– static atmosphere model grids of synthetic colours.
(Castelli & Kurucz, 2003, IAUS, 210, 20)
Not needed:– spectroscopic radial velocity measurements,– magnitude and colour zero points.
Output:– Teff (), Vp (), R (), L (), (M), distance: d, reddening.
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94The non-linear fitting method needs appropriate initial curves.
Teff(): Teff – (V – IC) relation(Bessel et al., 1998, A&A, 333, 231, Table 8)
Vp():
Liu’s template Our Vrad – IC relation
(1991, PASP, 103, 205) based on 20 RRab’sVp and IC curves
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95The IPM was tested on 9 non-modulated RRab stars, each subjected spectroscopic Baade–Wesselink analyses previously.
Errors are estimated from runs with different internal settings.
For good quality light curves the IPM gives similarly accurate results to direct B–W analyses.
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TelescopeOutput radial velocity curves
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TelescopeComparison with earlier Baade–Wesselink results andwith empirical relations
empirical relations from Catelan et al. (2004, ApJS, 154, 633, Eq. 3)
Sandage & Tammann (2006, ARA&A, 44, 93, Eq. 9)
black symbols – IPM resultsgrey symbols – earlier BW results
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Telescope– There is no available simultaneous photometric and spectroscopic
observations of any Blazhko star extended enough to cover both the Blazhko and pulsation cycles sufficiently.
– Today the IP Method provides the only possibility to determine the variation of the physical parameters of Blazhko stars with modulation.
1. Parameters independent from Blazhko phaseare determined first, from the mean light curve:
M, d, colour zero points (reddening).
2. With these values fixed, IPM is run for each Blazhko phase. We obtain Teff(), R(), L() where denotes Blazhko phase.
3. Averaging by pulsation phasevariations only with Blazhko phase remain: Teff(), R(), L().
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TelescopeMW Lyr XY And DM Cyg RR Gem SS
Cnc
A / <A>
P / <P>
R / <R>
L / <L>
T / <T>
Thank you!Thank you!