Why do O and B type stars have weaker hydrogen absorption lines?
So, most of the electrons in hydrogen are stuck on the ground orbit because they cannot absorb the lower energy light. This results in weaker absorption lines, because very few hydrogen atoms are participating. You cannot measure the temperature of the star based only upon its hydrogen line strengths.
Why are hydrogen absorption lines not seen in the hottest stars?
However, lines of hydrogen are not seen in the spectra of the hottest and the coolest stars. In the atmospheres of the hottest stars, hydrogen atoms are completely ionized. Because the electron and the proton are separated, ionized hydrogen cannot produce absorption lines.
Why do cool stars have weak hydrogen lines?
If the star is too hot or too cold, the hydrogen lines will be weak. If the temperature is too high, most of the hydrogen atoms will have their electrons starting out at higher energy levels. If the temperature is too low, most of the hydrogen atoms will have their electrons starting out from the ground state.
Do hotter stars have shorter wavelengths?
Hotter stars have spectra which peak at bluer (shorter) wavelengths. In cold stars with LOW surface temperatures, the sluggish atoms and molecules in the atmosphere do not have enough energy to move around as fast as those in a hotter gas.
What are the two different life cycles of stars?
Heavy stars turn into supernovae, neutron stars and black holes whereas average stars like the sun end life as a white dwarf surrounded by a disappearing planetary nebula. All stars, however, follow roughly the same basic seven-stage life cycle, starting as a gas cloud and ending as a star remnant.
What are the stages of a star going supernova?
(A Red Supergiant,below). Stage 3 – In the next million years a series of nuclear reactions occur forming different elements in shells around the iron core. Stage 4 – The core collapses in less than a second, causing an explosion called a Supernova, in which a shock wave blows of the outer layers of the star.
How long does it take for a Nebula to fade?
[+] As the core contracts, it heats up, illuminating the gas in a planetary nebula. Over about 20,000 years, that nebula will fade away, eventually becoming invisible.
Can a nebula disappear?
At its present rates of fading, they estimate, the nebula will be barely detectable in 20 or 30 years. Bottom line: Images taken 20 years apart show a dramatic fading for the Stingray Nebula, formerly known as the youngest planetary nebula.
What causes a planetary nebula to fade away?
A Planetary Nebula Like This Will Only be Visible for About 10,000 Years Before it Fades Away. For some stars, their last act is a final exhalation of gases, which we call a planetary nebula. As the last breath expands and travels away from the star that exhaled it, it will become diffuse and will no longer be visible.