... outer edges of the dust shell are fairly sharp, indicating a sharp drop in dust density possibly corresponding to the onset of dust production in a previous outburst; and (e) there are numerous voids in the dust, suggestive of a "Swiss-cheese" structure ...
... The energy input from the combined influence of UV radiation, stellar winds, and supernovae from massive stars makes "swisscheese" out of the ISM. ...
... These fledgling stars, only a few million years old, are bursting out of their dusty cocoons and producing bubbles of reddish glowing hydrogen gas.</p> <p>The excavated regions give a colorful "Swisscheese" appearance to the spiral arm. ...
... These fledgling stars, only a few million years old, are bursting out of their dusty cocoons and producing bubbles of reddish glowing hydrogen gas.</p> <p>The excavated regions give a colorful "Swisscheese" appearance to the spiral arm. ...