SCG 0018-4854: A YOUNG AND DYNAMIC GROUP

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SCG 0018-4854A YOUNG AND DYNAMIC GROUP
V. Presotto1,2, A. Iovino1 , E. Pompei 3, G.
Temporin4
1INAF-OABrera, Milano, I 2Università
dellInsubria, Como, I 3ESO-Chile 4Institute fur
Astrophysik, Innsbruck, A
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OUTLINE

• What are compact groups and why they are
  important?
• SCG0018-4854
• Results
• Conclusions

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COMPACT GROUPS (CGs)

• Selection criteria
• Richness n4 with (mm13)
• Isolation RN3RG
• Compactness mGlt26magarcsec-2

Stephans quintet
Seyferts sextet
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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
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SCG 0018-4854
From the SCGs cat (Iovino 2002)

• redshift V3300 km/s (46Mpc)
• richness 4 gal in close proximity, R20
  kpc
• density2 104.88 gal/Mpc-3
• velocity dispersion2 120 km/s

Galaxy V1 (km/s) Class2 Activity2 Notes
A (NGC 92) 3384 Saap SBG Tidal tail Double nuclei 3
B (NGC 89) 3284 SB0/a pec Sy2 Outflow 4
C (NGC 87) 3415 Irr SFG ---
D (NGC 88) 3432 SBab pec LINER ---
1 This work 2 Pompei et al. 2007 3 Danks
Alcaino 1981 4 Temporin et al. 2005
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SCG 0018-4854
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NGC 92
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NGC 92

• Asymmetric gas radial velocity curve AP23 gt
  recent interaction
• presence of a 8-shape1 along minor axis gt
  Nuclear bar misaligned with respect to PA major
  axis

0.2Gyrlttcolllt0.7Gyr
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NGC 89
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NGC 89

• Asymmetric stellar/gas radial velocity curve
  AP33-24 gt recent interaction
  0.2Gyrlttcolllt0.7Gyr
• NLR presence of gas multiple components (3/4)

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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

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NGC 88
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NGC 88

• Low surface brightness tidal tail
• 14x10kpc SW direction

Gas gt regular pattern of rotation
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NGC 87
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NGC 87 (major minor axis)
Ha

• Face-on irregular
• Star forming regions Ha
• Velocity gradients along Mm axis
• peculiar motions

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CONCLUSIONS

• We found peculiar kinematics and morphological
  distortions probably due to interactions among
  galaxies
• No double nucleus for NGC 92
• Recent interaction 0.2Gyrlttcolllt0.7Gyr
• Spectroscopical confirmation of the
  galactic-scale outflow of NGC 89

Presotto et al. 2009 in preparation
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Thanks
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SCG 0018-4854 X-ray
Trinchieri et al. 2008
KT 0.2 keV gt coolest system detected so far
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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
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SCG 0018-4854 gal properties
Galaxy V1 (km/s) Class2 Activity2 Notes B mag1 M H (109 Mo)I
A (NGC 92) 3384 Saap SBG Tidal tail Double nuclei 3 13.81 gt3.29
B (NGC 89) 3284 SB0/a pec Sy2 Outflow 4 14.18 lt0.02
C (NGC 87) 3415 Irr SFG --- 14.67 0.81
D (NGC 88) 3432 SBab pec LINER --- 14.98 2.52