These photos are from a 53 year old woman whose last menstruation was 1.5 years ago. She has had three vaginal births, most recently 15 years ago. She is sexually active with a male partner about once a day, though all of these photos were not taken near intercourse or arousal.
The os is angled upwards and to the right of this photograph. Some of the white seen on around the os and on the cervix is a reflection from the metal speculum and flash. The woman mentioned that she had the speculum inserted for a long time trying to get a good photograph, so the cervix became a bit drier than it was upon initial exam.
This photo was taken three weeks after the first. The speculum is positioned differently and the os is not visible more centrally.
This photo was taken a month after the second photo. Here you can see that the os is slightly open, perhaps being drawn open by the bottom bill of the speculum. It is normal for women who have given birth vaginally to have oses that are slightly slit shaped or open slightly.