The 3D structure of the Virgo cluster from H-band Fundamental Plane and Tully-Fisher distance determinations

We undertook a surface photometry survey of 200 galaxies in the Virgo clust er (complete to B < 14.0 mag) carried out in the near-infrared (NIR) H band . Combining velocity dispersion measurements from the literature with new s pectroscopic data for 11 galaxies, we derive distances of 59 early-type gal axies using the Fundamental Plane (FP) method. The distances of another 75 late-type galaxies are determined using the Tully-Fisher (TF) method. For t his purpose we use the maximum rotational velocity, as derived from H I spe ctra from the literature, complemented with new H alpha rotation curves of eight highly H I-deficient galaxies. The zero-points of the FP and TF templ ate relations are calibrated assuming the distance modulus of Virgo mu(0) = 31.0, as determined with the Cepheids method. Using these 134 distance det erminations (with individual uncertainties of 0.35 mag (TF) and 0.45 mag (F P)) we find that the distance of cluster A, associated with M87, is mu(0) = 30.84 +/- 0.06. Cluster B, offset to the south, is found at mu(0) = 31.84 +/- 0.10. This subcluster is falling on to A at about 750 km s(-1). Clouds W and M are at twice the distance of A. Galaxies on the north-west and sout h-east of the main cluster A belong to two clouds composed almost exclusive ly of spiral galaxies with distances consistent with A, but with significan tly different velocity distributions, suggesting that they are falling on t o cluster A at approximately 770 km s(-1) from the far side and at 200 km s (-1) from the near side respectively. The mass of Virgo inferred from the p eculiar motions induced on its vicinity is consistent with the virial expec tation.