We present a stellar population synthesis study of a type I luminous infrared galaxy ( LIRG ) : IRAS F13308+5946 .
It is a quasar with absolute magnitude M _ { i } = -22.56 and has a spectral feature of a Seyfert 1.5 galaxy .
Optical images show characteristics of later stages of a merger .
With the help of the stellar synthesis code starlight ( Cid Fernandes et al .
2005 ) and both Calzetti et al .
( 2000 ) and Leitherer et al. ’ s ( 2002 ) extinction curves , we estimate the past infrared ( IR ) luminosities of the host galaxy and find it may have experienced an ultraluminous infrared galaxy ( ULIRG ) phase for nearly 300 Myr , so this galaxy has probably experienced a type I ULIRG phase .
Both nuclear starburst and active galactic nuclei ( AGN ) contribute to the present IR luminosity budget , and starburst contributes \sim 70 % .
The mass of supermassive black-hole ( SMBH ) is M _ { BH } = 1.8 \times 10 ^ { 8 } M _ { \odot } and the Eddington ratio L _ { bol } / L _ { Edd } is 0.12 , which both approximate to typical values of PG QSOs .
These results indicate that IRAS F13308+5946 is probably at the transitional phase from a type I ULIRG to a classical QSO .