Redshift and distances
Redshift and distances
When AMIGA project started in 2003, we could find redshift data for about double number of CIG galaxies than were previously reported in other CIG related papers (Verdes-Montenegro et al 2005).
Because a significant number of new data are available for the sample since the project started, we have revised the apparent magnitudes, morphological types, velocities, distances, and optical luminosities for the CIG sample among others, with respect to those used in Verdes-Montenegro et al. (2005) and Lisenfeld et al. (2007). In the frame of the Wf4Ever project, the revision of these properties was partially automated by the implementation of scientific workflows that ask for and gather values of some of the properties for all AMIGA galaxies from the HyperLeda catalog.
This 2012 Release of AMIGA data has been published in the paper “The AMIGA sample of isolated galaxies X. A first look at isolated galaxy colors” (Fernández Lorenzo et al 2012).
In particular we searched for new velocities for those CIG with heliocentric velocities (Vhel) higher than 1000 km s−1, because for lower values redshift-independent distance estimates were preferred, and the same as in Verdes-Montenegro et al. (2005) were kept. The value of Vhel for a galaxy with available redshift data was updated when the errors quoted in the recent bibliography were smaller than in our previous compilation. For a subset of galaxies we found that the source of the data provided in NED (NASA/IPAC Extragalactic Database) were obtained from Stocke et al. (2004) but, while the paper was providing galactocentric velocities, NED was quoting them as heliocentric. This error was reported to the NED team and was corrected in both NED and in our database. Only for 40 CIG galaxies velocity data were not found in the bibliography, hence 1010 out of 1050 CIG galaxies currently have redshift measures. Distances were obtained from Virgo-centric velocities (Vvir) as D = Vvir/H0 (using H0 = 75 km s−1 Mpc−1), where Vvir is calculated from the heliocentric velocity Vhel and galactic coordinates following HyperLeda convention. Virgo-centric velocities were calculated as Vhel = Vlg+208 cos(θ), where Vlg is the radial velocity with respect to the Local Group and θ is the angular distance between the galaxy and Virgo center. In order to transform the Vhel to Vvir we transformed α and δ coordinates in Leon & Verdes-Montenegro (2003) to l and b values.