What is ionized helium?
Singly ionized helium is an atom that has lost one of its electrons. We must expect its remaining electron to act like a hydrogen electron. There is only one difference between a hydrogen atom and a singly ionized helium atom; number of protons in the nucleus, so the nuclear charge.
What is the difference between HI and H II?
Such regions of ionized hydrogen are called HII regions, while cold un-ionized hydrogen clouds are termed HI regions (with the I and II referring to the ionization state of the hydrogen). Thus, as a rule of thumb we expect significant H II regions near B1 or hotter stars.
Why are H II regions red?
The strongest hydrogen emission line, the H-alpha line at 656.3 nm, gives H II regions their characteristic red colour. (This emission line comes from excited un-ionized hydrogen.) Most of the rest of an H II region consists of helium, with trace amounts of heavier elements.
What direct evidence do astronomers have that supports the heavy element formation in stars?
Second, close study of one type of nucleus—a rare and unstable one named technetium—provides direct evidence that heavy-element formation really does occur in massive stars. This nucleus, well heavier than iron, is known from laboratory measurements to have a radioactive half-life of ~200,000 years.
What is the reason a Type 1 supernova slows its dimming?
The two types are both closely related to evolution of white dwarfs. What is the reason a type-I supernova slows its dimming after about 2 months? Energy is released from the decay of radioactive cobalt 56 to iron 56. decay of nickel 56 and cobalt 56 in a supernova remnant.
What made Supernova 1987A so useful?
What made supernova 1987a so useful to study? We saw direct evidence of nickel to iron decay in its light curve. In the Large Magellanic Cloud, we already knew its distance. Its progenitor had been observed previously.
What can you conclude about a Type 1 supernova?
What can you conclude about a Type I supernova? It was originally a low-mass star. In order of visual luminosity at the start, which is most luminous? rich in hydrogen from the outer envelope of the collapsed star.
What produces a Type 1 supernova?
What produces a type I supernova? decay of nickel 56 and cobalt 56 in a supernova remnant. in the core collapse that set the stage of Type II supernovae.