Ultraviolet Properties Early-Type dwarf Galaxies in the

Virgo Cluster.

Suk Kim and Soo-Chang Rey Astronomy and Space Science, Chungnam National University

Motivation• UV properties of different morphological Early-Type

dwarf galaxies

• Environmental effects for the UV properties of dwarf ellip-tical galaxies.

We found the dwarf lenticulars and peculiar dwarf ellipticals show distinct locus from that of ordinary dwarf ellipticals in CMR.

Early type dwarf galaxies far from the center of the Virgo cluster (r>2o to the M87; small red circles) shows larger UV fluxes than those near the center of cluster center (r<2o to the M87; large red circles): These UV bright dwarf galaxies located at outer part of the Virgo cluster are possible candidates showing recent star formation activity.

DATA1. GALEX GR3 : Mosaic Fields of GALEX UV Data2. SDSS DR5 : u,g,r,i,z Optical Data3. GOLDMine Data Base

Previous Work(Boselli et al. 2007)

CMR : Color Magnitude Relation(GALEX UV data and GOLDmine data base )

E : EllipticalsS0 : LenticularsdE : Dwarf EllipticalsdS0 : Dwarf LenticularsdE,N : Nucleated dEdEdi : dE with disk dEbc : dE with blue centerBCD : Blue Compact Dwarf

We found the dwarf lenticulars as well as recently discovered peculiar dwarf ellipticals (with disk and blue center), show distinct locus (yellow rectangulars)from that of ordinary dwarf ellipticals in CMRs. This indicates the UV propertiesof these dwarf galaxies are different to those of ordinary dwarf ellipticals, suggesting different formation and evolution(e.g., star formation activity).

Environmental effect(GALEX UV and SDSS data)

Projected spatial distribution of early-type dwarf galaxies matching between GALEX and SDSS within the Virgo cluster Inner circle represents the bound-ary of the 2 degree radius to the M87.

: dE : dS0 : dE,N : dEdi : dEbc: BCD

CMR : Color Magnitude Relation(GALEX UV data and SDSS optical data )

: dE : dS0 : dE,N : dEdi : dEbc: BCD

Big symbols : Inner galaxies (r < 2o) Small symbols : Outer galaxies (r > 2o)

Outer galaxies bluer

Color – Color Relation (GALEX UV data and SDSS optical data )

Big symbols : Inner galaxies (r < 2o) Small symbols : Outer galaxies (r > 2o)

: dE : dS0 : dE,N : dEdi : dEbc: BCD

These UV bright dwarf galaxies located at outer part of the Virgo cluster are possible candidates showing recent star formation activity.

Hα

Hα

Hα

1Gyr

5Gyr

10~15 Gyr

Conclusion

- Ultraviolet properties of early-type dwarf galaxies in the Virgo cluster using the GALEX UV data and SDSS optical data.

- Different morphological dwarf galaxies show different UV to optical color magnitude relation(CMRs)

- Since dwarf galaxies depend on cluster environments effect, the far from cluster center show larger UV fluxes than those near the center.