Don’t be alarmed, but the photo featured on the Astronomy Picture of the Day website this Wednesday (25) brings the Bicho-Papão Nebula, found close to the plane of the Milky Way. In the image highlighted by NASA, the nebula appears with its dark shapes in contrast to the brightness of several stars in the background.
- What is a nebula and how does it form?
- How are space photos taken?
Cataloged as “LDN 1622”, this nebula ended up with the nickname because, for some, its shape resembles that of the frightening being of children’s imagination. In the photo, it appears with its dark form in contrast to gaseous hydrogen, visible only in photographs captured through long exposures.
In addition to the dark nebula, the photo also features reflection nebula vdB 62, which can be easily found in the upper right corner. As the name implies, reflection nebulae are clouds of dust that reflect light from one or more nearby stars.
It may not look like it, but there are young stars hidden in the darkness of the Boogeyman Nebula. They were revealed in observations by the Spitzer Space Telescope, which ended its mission in 2020.
What are dark nebulae
The Bicho-Papão Nebula is considered a dark nebula, that is, it is an interstellar cloud composed of so much dust that the visible light that falls on it is absorbed and scattered. These nebulae are known for their irregular and undefined shapes.
Although it is difficult to observe them in visible light wavelengths, these nebulae can be “revealed” when they are in front of a bright emission nebula or a star-rich region, as was the case in the photo above.
The temperature of dark nebulae is between 10 and 100 K (the equivalent of -263.15 ºC and -173.15 ºC, respectively), allowing hydrogen molecules to form and thus start the formation of new stars.