For refcode 1988ApJ...331..620K: Retrieve 139 NED objects in this reference. Please click here for ADS abstract
NED Abstract
Copyright by American Astronomical Society.
Reproduced by permission
1988ApJ...331..620K
21 CENTIMETER LINE WIDTH DISTANCES OF CLUSTER GALAXIES AND
THE VALUE OF H_0_
R. C. KRAANKORTEWEG, L. M. CAMERON, AND G. A. TAMMANN
Astronomisches Institut der Universitat Basel
Received 1987 September 30; accepted 1988 February 8
ABSTRACT
Locally calibrated blue and infrared TullyFisher (TF) relations are
applied to an essentially (i.e., 82%) complete sample of 81 SabSm galaxies
which are bona fide members of the Virgo Cluster. Because of the proximate
completeness of the sample a nearly unbiased Virgo modulus of (m  M)^0^ =
31.60 + 0.15 can be derived. The result is in perfect agreement with
independent recent determinations which gives additional justification
to the adopted local calibrators. The distance modulus from the blue TF
relation carries higher weight because infrared H magnitudes are available
for only 25 Virgo members. The remaining H magnitudes are derived from a
well defined (BH)/log {DELTA}v_21_ relation; nevertheless, the 25 members
suffice to show that the bTF and iTF relations give almost identical
distance moduli from any selected Virgo subsample. The intrinsic scatter
about the two TF relations is {sigma}_M_ = 0.7 mag. This is considerably
larger than the observed scatter in the UMa Cluster and in 10 more distant
clusters for which B and H magnitudes and 21 cm line widths are available;
their reduced scatter discloses that the hitherto investigated samples
merely contain the brightest spirals at any given line width. Distance
determinations of these clusters can therefore only be achieved by fitting
the upper envelopes of their TF relations onto the blue and infrared upper
envelopes of the Virgo Cluster. The resulting distances define a linear
expansion law with a small scatter. The linearity of the expansion can be
extended for the range from v ~ 200 km s^1^ out to v ~ 20,000 km s^1^
using external data. The present cluster data require a Hubble constant of
H_0_ = 56.6 +/ 0.9 km s^1^ Mpc^1^ which implies through firstranked
cluster galaxies 51 < H_0_(global) < 56 at very large distances; the
external error of these values is probably less than 20%. A search for
Local Group motion toward the microwave background dipole remains
inconclusive.
Subject headings: galaxies: clustering  galaxies: distances  radio
sources: 21 cm radiation  cosmology
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