We use both photometric and spectroscopic data from the Hubble Space Telescope to explore the relationships among 4000 Å break ( D4000 ) strength , colors , stellar masses , and morphology , in a sample of 352 galaxies with log ( M _ { * } / M _ { \odot } ) > 9.44 at 0.6 \lesssim z \lesssim 1.2 .
We have identified authentically quiescent galaxies in the UVJ diagram based on their D4000 strengths .
This spectroscopic identification is in good agreement with their photometrically-derived specific star formation rates ( sSFR ) .
Morphologically , most ( that is , 66 out of 68 galaxies , \sim 97 % ) of these newly identified quiescent galaxies have a prominent bulge component .
However , not all of the bulge-dominated galaxies are quenched .
We found that bulge-dominated galaxies show positive correlations among the D4000 strength , stellar mass , and the Sérsic index , while late-type disks do not show such strong positive correlations .
Also , bulge-dominated galaxies are clearly separated into two main groups in the parameter space of sSFR vs. stellar mass and stellar surface density within the effective radius , \Sigma _ { e } , while late-type disks and irregulars only show high sSFR .
This split is directly linked to the ‘ blue cloud ’ and the ‘ red sequence ’ populations , and correlates with the associated central compactness indicated by \Sigma _ { e } .
While star-forming massive late-type disks and irregulars ( with D4000 < 1.5 and log ( M _ { * } / M _ { \odot } ) \gtrsim 10.5 ) span a stellar mass range comparable to bulge-dominated galaxies , most have systematically lower \Sigma _ { e } \lesssim 10 ^ { 9 } M _ { \odot } { kpc ^ { -2 } } .
This suggests that the presence of a bulge is a necessary but not sufficient requirement for quenching at intermediate redshifts .