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SCG 0018-4854: A YOUNG AND DYNAMIC GROUP

SCG 0018-4854: A YOUNG AND DYNAMIC GROUP. V. Presotto 1,2 , A. Iovino 1 , E. Pompei 3 , G. Temporin 4. 1 INAF-OABrera, Milano, I 2 Università dell’Insubria, Como, I 3 ESO-Chile 4 Institute fur Astrophysik, Innsbruck, A. OUTLINE. What are compact groups and why they are important?

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SCG 0018-4854: A YOUNG AND DYNAMIC GROUP

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  1. SCG 0018-4854:A YOUNG AND DYNAMIC GROUP V. Presotto1,2, A. Iovino1 , E. Pompei 3, G. Temporin4 1INAF-OABrera, Milano, I 2Università dell’Insubria, Como, I 3ESO-Chile 4Institute fur Astrophysik, Innsbruck, A Lucchin School -Bertinoro-

  2. OUTLINE • What are compact groups and why they are important? • SCG0018-4854 • Results • Conclusions Lucchin School -Bertinoro-

  3. COMPACT GROUPS (CGs) • Selection criteria: • Richness: n≥4 with (m≤m1+3) • Isolation: RN≥3RG • Compactness: mG<26mag∙arcsec-2 • Properties: • Low dispersion: <s>≈200km/s • High density: 300<dgroup<108h2Mpc-2 • Lifetime ? tcross≈0.016 1/H0 Stephan’s quintet SCGs sample: Dmmember<Dmiso Dm=mest-mint>4 (Iovino 2002) (Hickson 1982;1992) NEW Seyfert’s sextet Lucchin School -Bertinoro-

  4. Tidal forces => morphological distorsion and disturbed kinematics • Gas infall => triggering of strong burst of star formation or feeding an AGN • Galaxies merger => new galaxy + TDGs INTERACTIONS IN CGs Compact groups are perfect laboratories to test galaxies’ interactions Aim: reveal evidence of interaction in SCG 0018-4854 to investigate its evolution history Lucchin School -Bertinoro-

  5. SCG 0018-4854 From the SCGs cat (Iovino 2002) • redshift: V≈3300 km/s (≈46Mpc) • richness: 4 gal in close proximity, R≈20 kpc • density2: 104.88 gal/Mpc-3 • velocity dispersion2: ≈120 km/s 1 This work 2 Pompei et al. 2007 3 Danks & Alcaino 1981 4 Temporin et al. 2005 Lucchin School -Bertinoro-

  6. SCG 0018-4854 Data from FORS2 @ VLT/ESO Multi-slit spectroscopy: M & m axis (except M axis NGC 88) Grism: 1400V with l0 5200Å 20.8Å/mm (0.49 Å/px) Texp: 4X2699s Photometry: all gal Filters: 1. R-band 6550Å (FWHM 1650Å) 2. Ha 6615Å (FWHM 61Å) Texp: 3X119s (R-band) 3X100s (Ha) R-band Lucchin School -Bertinoro-

  7. NGC 92 Lucchin School -Bertinoro-

  8. NGC 92 Ha K • Asymmetric gas radial velocity curve: AP=23% => recent interaction: • presence of a 8-shape1 along minor axis => Nuclear bar misaligned with respect to PA major axis 0.2Gyr<tcoll<0.7Gyr Lucchin School -Bertinoro-

  9. NGC 89 Lucchin School -Bertinoro-

  10. NGC 89 • Asymmetric stellar/gas radial velocity curve: AP=33-24% => recent interaction: 0.2Gyr<tcoll<0.7Gyr • NLR: presence of gas multiple components (3/4) Lucchin School -Bertinoro- Fig D

  11. NGC 89 Ha Temporin et al. 2005 • SW direction: steep rise of gas velocity • Spectroscopical confirmation of the galactic-scale outflow • Not clear correlation between outflow & surrounding gas Lucchin School -Bertinoro-

  12. NGC 88 Lucchin School -Bertinoro-

  13. NGC 88 R-band • Low surface brightness tidal tail • ≈14x10kpc SW direction Gas => regular pattern of rotation Lucchin School -Bertinoro-

  14. NGC 87 Lucchin School -Bertinoro-

  15. NGC 87 (major & minor axis) Ha • Face-on irregular • Star forming regions Ha • Velocity gradients along M&m axis • + peculiar motions Lucchin School -Bertinoro-

  16. CONCLUSIONS • We found peculiar kinematics and morphological distortions probably due to interactions among galaxies • No double nucleus for NGC 92 • Recent interaction: 0.2Gyr<tcoll<0.7Gyr • Spectroscopical confirmation of the galactic-scale outflow of NGC 89 Presotto et al. 2009 in preparation Lucchin School -Bertinoro-

  17. Thanks Lucchin School -Bertinoro-

  18. SCG 0018-4854 X-ray Trinchieri et al. 2008 KT ≈ 0.2 keV => coolest system detected so far Lucchin School -Bertinoro-

  19. SCG 0018-4854 X-ray • Phase 3b • Hi bridge between NGC 92 and NGC 88 • NGC 89 completely stripped of HI Pompei et al.2007 Lucchin School -Bertinoro-

  20. SCG 0018-4854 gal properties Lucchin School -Bertinoro-

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