Large-scale structure and galaxy motions in the Leo/Cancer constellations

• Published in: Astrophysical bulletin 2015, Vol.70 (1), p.1-15
• Main Authors: Karachentsev, I. D., Nasonova, O. G., Karachentseva, V. E.
• Format: Article
• Language: English
• Subjects: Astronomy; Astrophysics; Astrophysics and Cosmology; Clouds; Density; Dispersions; Dwarf galaxies; Estimates; Kinematics; Orbitals; Orbits; Physics; Physics and Astronomy; Radial velocity; Stars & galaxies; Stellar mass
• ISSN: 1990-3413; 1990-3421
• DOI: 10.1134/S1990341315010010

In the region of the sky limited by the coordinates RA = 7ḥ0-12ḥ0, Dec = 0°...+20° and extending from the Virgo Cluster to the South Pole of the Local Supercluster, we consider the data on the galaxies with radial velocities V LG ≲ 2000 km/s. For 290 among them, we determine individual distances and peculiar velocities. In this region, known as the local velocity anomaly zone, there are 23 groups and 20 pairs of galaxies for which the estimates of virial/orbital masses are obtained. A nearby group around NGC3379 = Leo I and NGC3627 as well as the Local Group show the motion from the Local Void in the direction of Leo cloud with a characteristic velocity of about 400 km/s. Another rich group of galaxies around NGC3607 reveals peculiar velocity of about −420 km/s in the frame of reference related with the cosmic background radiation. A peculiar scattered association of dwarf galaxies Gemini Flock at a distance of 8 Mpc has the radial velocity dispersion of only 20 km/s and the size of approximately 0.7 Mpc. The virial mass estimate for it is 300 times greater than the total stellar mass. The ratio of the sum of virial masses of groups and pairs in the Leo/Can region to the sum of stellar masses of the galaxies contained in them equals 26, which is equivalent to the local average density Ω m (local) = 0.074, which is 3–4 times smaller than the global average density of matter.