Answer based on context:

AH Velorum is a Cepheid variable located less than a degree to the northeast of Gamma. A yellow-white supergiant of spectral type F7Ib-II, it pulsates between magnitudes 5.5 and 5.89 over 4.2 days. Also lying close to Gamma, V Velorum is a Cepheid of spectral type F6-F9II ranging from magnitude 7.2 to 7.9 over 4.4 days. AI Velorum is located 2.8 degrees north-northeast of Gamma, a Delta Scuti variable of spectral type A2p-F2pIV/V that ranges between magniudes 6.15 and 6.76 in around 2.7 hours.

How many days difference is there between the F7Ib-II and the F6-F9II?
.2