A chalazion is a small bump that appears on your eyelid because of a blocked oil gland.It can develop on the lower or upper eyelid, and it often disappears without treatment in about one month. chalazion is a small bump that appears on your eyelid because of a blocked oil gland.
Artist's conception of a white dwarf accreting hydrogen from a larger companion. A nova (plural novae or novas) is a cataclysmic nuclear explosion on a white dwarf, which causes a sudden brightening of the star.Novae are not to be confused with other brightening phenomena such as supernovae or luminous red novae.he recurrence interval for a nova is less dependent on the white dwarf's accretion rate than on its mass; with their powerful gravity, massive white dwarfs require less accretion to fuel an outburst than lower-mass ones.
A helium nova (or helium flash) is a proposed category of nova explosion that lacks hydrogen lines in the spectrum. This may be caused by the explosion of a helium shell on a white dwarf.he time taken for a nova to decay by 2 or 3 magnitudes from maximum optical brightness is used to classify a nova via its speed class. A fast nova will typically take less than 25 days to decay by 2 magnitudes and a slow nova will take over 80 days.