Dátum: 2001. június 4., 15:32
Feladó: Külső hozzászóló --
Tárgy: a vilagrejtely megoldodott!
T. Csilla-olvasok,
Mivel mar napok ota szinte semmi nem tortenik eme forumon, hadd hivjam fel
a figyelmet arra, hogy a vilagrejtely (the ultimate solution of world mystery)
2001. majus 20-an megoldodott.
De a trefat felreteve, annyi valoban tortent, hogy publikaltak a Hubble
Key Project (a Hubble-allando meghatarozasa a HST meresei alapjan) un.
vegso eredmenyeit. Ime a Wendy Freedman es munkatarsai cikkenek kivonata,
ami szerint a Hubble-allando legujabb erteke 72+/-8 km/s/Mpc.
Varjuk a konkurrens kutatocsoportok reakcioit...
Final Results from the Hubble Space Telescope Key Project to
Measure the Hubble Constant
(Freedman et al. ApJ 553, 47)
We present here the final results of the Hubble Space Telescope (HST) Key
Project to measure the Hubble constant. We summarize our method, the
results, and the uncertainties, tabulate our revised distances, and give
the implications of these results for cosmology. Our results are based on
a Cepheid calibration of several secondary distance methods applied over
the range of about 60-400 Mpc. The analysis presented here benefits from a
number of recent improvements and refinements, including (1) a larger LMC
Cepheid sample to define the fiducial period-luminosity (PL) relations,
(2) a more recent HST Wide Field and Planetary Camera 2 (WFPC2)
photometric calibration, (3) a correction for Cepheid metallicity, and (4)
a correction for incompleteness bias in the observed Cepheid PL samples.
We adopt a distance modulus to the LMC (relative to which the more distant
galaxies are measured) of mu_0 = 18.50 ± 0.10 mag, or 50 kpc. New, revised
distances are given for the 18 spiral galaxies for which Cepheids have
been discovered as part of the Key Project, as well as for 13 additional
galaxies with published Cepheid data. The new calibration results in a
Cepheid distance to NGC 4258 in better agreement with the maser distance
to this galaxy. Based on these revised Cepheid distances, we find values
(in km s-1 Mpc-1) of H0 = 71 ± 2 ± 6 (systematic) (Type Ia supernovae), H0
= 71 ± 3 ± 7 (Tully-Fisher relation), H0 = 70 ± 5 ± 6 (surface brightness
fluctuations), H0 = 72 ± 9 ± 7 (Type II supernovae), and H0 = 82 ± 6 ± 9
(fundamental plane). We combine these results for the different methods
with three different weighting schemes, and find good agreement and
consistency with H0 = 72 ± 8 km s-1 Mpc-1. Finally, we compare these
results with other, global methods for measuring H0.
Kiss Laszlo