Love Astronomy Style

Given the day, I’m attaching a lovely picture taken of the Heart Nebula as a Valentine to you all. The picture was taken by an astronomy enthusiast named Adam Jensen, and is actually today’s Astronomy Picture of the Day. The picture shows two overlapping bubbles blown out by the hot blue cluster of stars near the centre named Melotte 15, of which some are about 50 times the mass of the Sun. Such stars are so hot, they produce a lot more ultraviolet light than the Sun does, and this light does a fine job of stripping the electrons off the hydrogen atoms floating in their vicinity, i.e., ionizing them. Indeed, the outline of the Heart is where the ultraviolet light is hitting the pushed out gas. The red colour actually comes from some of those freed electrons pairing up with the previously stripped nuclei, and emitting a specific wavelength of red light (656.28 nm) as the electron quantum mechanically transitions from the hydrogen’s third lowest energy level to its second. This wavelength, known as “H alpha,” is a common indicator of locations where hot stars are ionizing nearby gas, and can show where such stars are forming across entire galaxies. Anyway, in this case, you can also see pillars which are the leftovers of nearby dense gas in the vicinity that have been slowly eroded by the ultraviolet light and the winds from the young stars. Indeed, these pillars generally point back toward where the nearby hot stars are located. This particular nebula is located in the northern constellation of Cassiopeia, and is around 7,500 light years away and about 200 light years wide. In a sharp pivot back to reality, the fiddly bit at the bottom of the Heart Nebula is the far less romantically named Fish Head Nebula, and is a younger version of the bubbles nearby. Happy Valentine’s Day, everyone!