Age and Dust Degeneracy for Starburst Galaxies Solved?

A spectral evolution model of galaxies that includes both stellar and dusteffects is newly built. xApplying the model to 22 nearby starburst galaxies, wehave shown that far infrared luminosity of galaxies helps to break theage-dustiness degeneracy. We have derived a unique solution of age and thedustiness for each starburst galaxy. The resulting starburst ages and opticaldepths are in the range $10 \le t (Myr) \le 500$ and $0.5 \le \tau_{V} \le5.0$, respectively. The result is robust and is almost independent of modelassumptions such as dust distributions, extinction curves, and burst strengths.With the rapidly growing sensitivity of submillimeter detectors, it shouldbecome possible in the near future to determine the age and $\tau_{V}$ ofstar-forming galaxies at redshifts $z \simeq 3$ and beyond. Accurate estimatesof $\tau_{V}$ for Lyman-break galaxies and high-z galaxies might require asubstantial revision of the previously claimed picture of star formationhistory over the Hubble time.Comment: Latex (aas2pp4) 15 pages, 1 table, 6 figures. Accepted for Ap