Diapositiva 1

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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
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Contents of COROTSKY seismology programme

• Stars brighter than V9, 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 Charpinets
• presentation in CW8.

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(5) Absolute magnitude from Strömgren / Physpar

• Stars with Strömgren photometry in the Physpar
  windows not having ??/? lt 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 ?b - (8.929.6 ??)
  ?co 0.22 Fe/H
• Stars of region 5 (from G2) PENDING
• 50 stars of regions 6-8 (B0-G5 supergiants)

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G2-K type stars Mv calibration
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Definition of a well-controlled stellar sample
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How do the pre-Hipparcos calibrations behave?
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Olsen(1984)
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COROTSKY
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Lets see an example

• HD46241. ?(Mv)-6.809. Classified by Physpar as
  K0V.
• p 6.3
• s(p)/ p 0.149 ? d 159 pc. ? Av 0
• V 5.83 ? Mv(p) -0.18
• ? It cannot be a MS star

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COROTSKY
T T T T T t

• GKM giants have Mv in the range 0.0, -0.5
• GKM MS have Mv gt 5
• Stars having ?Mv lt -5 are giants wrongly
  classified.

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COROTSKY
T T T T T t

• GKM Main Sequence stars with V lt 9.5 are nearby
  stars ? they have good parallaxes ? classified in
  group (2) s(p)/plt0.1
• Stars with V lt 9.5 not having good parallaxes
  must be far ? they must be giants.

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Building the new calibration ...
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Same approach as for F0-G2 calibration
1) stars with ??/? lt 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 ??/? lt 15 (272 stars, unreddened)
• least-squares fit with 3-sigma clipping
• Mv(?)- Mv 0.08 6.78 ?mo

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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 lt
?co lt 0.25 ? 0.11 mag -0.05
lt ?mo lt 0.11 0.36 lt (b-y)olt
0.60
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24 stars ??/?lt6
COROTSKY
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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 s(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).