Campbell’s Hydrogen Star is also known as star HD 184738. It is at center of planetary nebula and reddish orange in color. The spectra of Wolf-Rayet introduced by Campbell were clearly defined as a spectrum of hydrogen bands.
During long research, he observed that some hydrogen spectra extend outside the specific area of the star.
The observed appearances surrounding the star are usually due to the envelope of the incandescent hydrogen.
This theory further established the concept that some Wolf-Rayet Stars are completely surrounded by a large nebula of ejected gases. This star was later defined as Campbell’s Hydrogen Star and was known by the same name by the astronomers after that.
In an experiment conducted in 3305, the experts observed a Wolf-Rayet star below one solar mass with M-class distance to the ½ solar mass. The surprising fact was that the surrounding hydrogen nebula for this star appeared to vanish due to the radiation pressure of the respective star.
The star in the middle of Campbell’s Hydrogen Star is recognized as HD 184738 and is called a rare WC star. These stars can be considered as variants of the Wolf Rayet Stars, they are hot and massive stars that keep on losing mass and discharge materials at a fast rate.
The Wolf-Rayet stars spectra present broad emission of lines of nitrogen, helium, silicon, oxygen, and carbon; however, the hydrogen lines are generally absent and weak.
The wolf-rayet stars can be subdivided as per the spectra of principal emission lines. Studies reveal that the massive stars are greatly dominated by ionized nitrogen; however, the WC stars with low mass such as HD 184738 are defined with carbon. Ultimately, the spectra of WC stars in the surroundings are dominated by the presence of oxygen.
Campbell’s Hydrogen Star is located 2 ½ degrees north of the Albireo. You can find Campbell’s Hydrogen Star shining at the magnitude of 11.3 and it is a popular sibling of other Wolf-Rayet stars.
The most important difference you need to know is that Wolf-Rayet stars have rich Nitrogen content along with some carbon in the surrounding atmosphere; however, the WC stars are known for rich Carbon and Oxygen content without the presence of Nitrogen. It is important to mention that the Planetary Nebula created by Campbell’s Hydrogen Star is not like a normal Planetary Nebula.
Instead, it is very small and appears very small even when seen from a telescope. When seen with size 5 arcseconds, it needs high power before becoming visible around the central WC star. As seen with medium or low magnification, this star is overlapped by the central star and cannot be brightened further with the Olll filter; therefore, it may appear challenging to locate this star.
Campbell’s Hydrogen Star was named after astronaut William Wallace Campbell in the 19th century. At that time, this popular American astronomer was serving as the director of the Lick Observatory.
He was an experienced specialist in spectroscopy and was much aware of widely referenced surveys linked to the Wolf-Rayet star spectra. This concept was discovered only 30 years ago before this new invention.