A new volume-limited sample of 84 isolated pairs of galaxies has been selected from the UZC catalogue. Galaxies in pairs are brighter than $M_{Zw}-5log h =-18.9$. The projected separation between pair members is $r < 200 h^{-1}$ kpc, the isolation criterion requires the pair to have no further companion within a $R=1 h^{-1}$ Mpc distance. Morphological classification for both members is available for 57 pairs. Out of these, 9 are early-type (E+E) pairs, 29 late type (S+S) pairs, and 19 mixed (E+S) pairs. We find a deficit of luminous dominants among E+E and E+S pairs relative to S+S pairs, while the distance between pair members is statistically undistinguishable. However, among the 12 pairs that are not only close but also luminous, the fraction of E+E and S+S pairs is 8% and 83% respectively. This result is consistent with star-formation being enhanced in S+S pairs (but not in spirals in S+E pairs) in extremely close isolated pairs.
V. Zitelli, P. Focardi, B. Kelm, S. Marinoni (2004). A new sample of isolated galaxy pairs. CAMBRIDGE : Cambridge Univ. Press.
A new sample of isolated galaxy pairs
FOCARDI, PAOLA;KELM, BIRGIT;
2004
Abstract
A new volume-limited sample of 84 isolated pairs of galaxies has been selected from the UZC catalogue. Galaxies in pairs are brighter than $M_{Zw}-5log h =-18.9$. The projected separation between pair members is $r < 200 h^{-1}$ kpc, the isolation criterion requires the pair to have no further companion within a $R=1 h^{-1}$ Mpc distance. Morphological classification for both members is available for 57 pairs. Out of these, 9 are early-type (E+E) pairs, 29 late type (S+S) pairs, and 19 mixed (E+S) pairs. We find a deficit of luminous dominants among E+E and E+S pairs relative to S+S pairs, while the distance between pair members is statistically undistinguishable. However, among the 12 pairs that are not only close but also luminous, the fraction of E+E and S+S pairs is 8% and 83% respectively. This result is consistent with star-formation being enhanced in S+S pairs (but not in spirals in S+E pairs) in extremely close isolated pairs.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
