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Progress report on the determination of absolute magnitudes using Strömgren photometry. C. Jordi, E. Solano Universitat de Barcelona LAEFF, Madrid COROT week 9: Dec-2005 Dec 5-9, 2005 Progress report on absolute magnitudes: COROT week 9 1 Contents of COROTSKY: seismology programme • Stars brighter than V=9, centre & anticentre directions. • 12000 stars. 6820 stars later than A5. • Hierarchical criteria for assigning Mv to a target. The criteria was reviewed in COROT week 7 (see Jordi, Solano & Ribas). Already adopted in COROTSKY (see Charpinet’s presentation in CW8. Dec 5-9, 2005 Progress report on absolute magnitudes: COROT week 9 2 Dec 5-9, 2005 Progress report on absolute magnitudes: COROT week 9 3 (5) Absolute magnitude from Strömgren / Physpar • “Stars with Strömgren photometry in the Physpar windows not having / < 0.1”. • 12 stars of “region1” (O-B) •3 stars of “region 2” (A0-A2) • 249 stars of “region 3” (late A) post-Hipp. calib (CW7) Mv = 1.88 + 5.2 (b-y) o – 9.1 co + + 4.9 mo + 2.7 10-6 vsini2 • 278 stars of “region 4” (F0-G2) post-Hipp. calib (CW7) Mv = Mv(ZAMS,) - 0.13 + 1.57 - (8.9+29.6 ) co + 0.22 [Fe/H] • Stars of “region 5” (from G2) PENDING • 50 stars of “regions 6-8” (B0-G5 supergiants) Dec 5-9, 2005 Progress report on absolute magnitudes: COROT week 9 4 G2-K type stars: Mv calibration Dec 5-9, 2005 Progress report on absolute magnitudes: COROT week 9 5 Definition of a well-controlled stellar sample Complete uvby- photometry in Hauch & Mermilliod (1998) Classified as “region 5” with PHYSPAR V in Hipparcos and Hauck & Mermilliod (1998) in agreement At least 2 measurements in Hauck & Mermilliod (1998) Spectral type in Hipparcos in agreement with photometry Not anomalous location in colour-colour diagrams Not supergiants according to photometry Not luminosity classes I & II according to spectral type in Hipparcos Not peculiar, variable or belonging in multiple systems (HIP flags) Not variable or joint photometry in Hauck & Mermilliod (1998) Not variable or belonging in multiple systems according to SIMBAD 303 stars: 272 with /<0.15 104 with /<0.1 Dec 5-9, 2005 Progress report on absolute magnitudes: COROT week 9 6 How do the pre-Hipparcos calibrations behave? Dec 5-9, 2005 Progress report on absolute magnitudes: COROT week 9 7 Olsen(1984) A trend with metallicity A slight trend with evolution Dec 5-9, 2005 Progress report on absolute magnitudes: COROT week 9 8 COROTSKY What’s happening here? Dec 5-9, 2005 Progress report on absolute magnitudes: COROT week 9 9 Let’s see an example • HD46241. Δ(Mv)=-6.809. Classified by Physpar as K0V. • π : 6.3 • σ(π)/ π: 0.149 d= 159 pc. Av = 0 • V= 5.83 Mv(π) = -0.18 It cannot be a MS star Dec 5-9, 2005 Progress report on absolute magnitudes: COROT week 9 10 COROTSKY What’s happening here? T • GKM giants have Mv in the range [0.0, -0.5] T T• GKM MS have Mv > 5 T • Stars having ΔMv < -5 are giants wrongly T t classified. Dec 5-9, 2005 Progress report on absolute magnitudes: COROT week 9 11 COROTSKY Why so many giants? T • GKM Main Sequence stars with V < 9.5 are nearby T stars they have good parallaxes classified in T group (2): σ(π)/π<0.1 T • Stars with V < 9.5 not having good parallaxes must T be far they must be giants. t Dec 5-9, 2005 Progress report on absolute magnitudes: COROT week 9 12 Building the new calibration ... Dec 5-9, 2005 Progress report on absolute magnitudes: COROT week 9 13 largest dependency Dec 5-9, 2005 Progress report on absolute magnitudes: COROT week 9 14 Same approach as for F0-G2 calibration 1) stars with / < 5 % (104 stars, small bias, unreddened) least-squares fit with 3-sigma clipping Mv()-Mv(ZAMS, (b-y) o)= 0.238 – [ 5.49 + 18.89(b-y)o ] co 2) stars with / < 15 % (272 stars, unreddened) least-squares fit with 3-sigma clipping Mv()- Mv = +0.08 – 6.78 mo Dec 5-9, 2005 Progress report on absolute magnitudes: COROT week 9 15 Dec 5-9, 2005 Progress report on absolute magnitudes: COROT week 9 16 The new calibration ... Mv = Mv(ZAMS,) + 0.238 – [ 5.49 + 18.89(b-y)o ] co – 6.78 mo ± 0.018 0.58 7.36 0.40 Valid for -0.10 < co < 0.25 -0.05 < mo < 0.11 0.36 < (b-y)o< 0.60 Dec 5-9, 2005 = 0.11 mag Progress report on absolute magnitudes: COROT week 9 17 COROTSKY 24 stars; /<6% =0.40 Trends have been removed =0.28 Dec 5-9, 2005 Progress report on absolute magnitudes: COROT week 9 18 Conclusions • A new Strömgren calibration has been derived for the G Main Sequence stars. • Both systematic and random errors have been reduced. • 249 late-A + 278 F0-G2 + 30 G2-K0 MS stars with Mv derived from Strömgren photometry using post-Hipparcos calibrations ready to be delivered to COROTSKY. •… BUT still too many stars without information on Mv… • New method: Spectral type & luminosity: σ(Mv) = 1 subtype - SIMBAD has been explored but VizieR has not. - To explore all the catalogues contained in VizieR using VO-like tools (e.g. vizquery). Dec 5-9, 2005 Progress report on absolute magnitudes: COROT week 9 19