Looking at the spectra of stars, we can classify the stars based on the appearance of different spectral lines in the star. Pickering & Fleming (1890s) developed a system based on the strength of the Balmer lines of hydrogens, with A stars being the having the strongest Balmer lines.
What spectral type of star has the strongest Balmer absorption lines?
The hydrogen lines in the visible part of the spectrum (called Balmer lines) are strongest in stars with intermediate temperatures—not too hot and not too cold.
Why are Balmer lines strong in the spectra?
The strength of the Balmer lines (that is, how much absorption they cause) depends on the temperature of the cloud. If the cloud is too hot, the electrons in hydrogen have absorbed so much energy that they can break free from the atom. … So, very cool stars will have weak Balmer series hydrogen lines, too.
Are the hydrogen Balmer lines weak medium or strong for each spectral class?
Again, there are very few hydrogen atoms with electrons in the second energy level, so the Balmer lines of these stars are weak. … The change in the strength of the hydrogen lines with the temperature can be easily seen if we graph the spectra of different classes of stars together and compare their hydrogen lines.
Which spectral type has the strongest hydrogen lines?
Spectral Types. Stars are divided into groups called spectral types (also called spectral classes) which are based on the strength of the hydrogen absorption lines. The A-type stars have the strongest (darkest) hydrogen lines, B-type next strongest, F-type next, etc.
What is our sun’s full spectral classification?
The full classification for our Sun is G2 V. The G2 spectral type means it is yellow-white in color and the luminosity class V means it a hydrogen-burning, main-sequence star.
What are the 7 spectral classes of stars?
Stars are classified by their spectra (the elements that they absorb) and their temperature. There are seven main types of stars. In order of decreasing temperature, O, B, A, F, G, K, and M.
Why do we only see 4 lines in the hydrogen emission spectrum?
This is explained in the Bohr model by the realization that the electron orbits are not equally spaced. … The electron energy level diagram for the hydrogen atom. He found that the four visible spectral lines corresponded to transitions from higher energy levels down to the second energy level (n = 2).
How many Balmer lines are in the spectrum?
Balmer lines are historically referred to as “H-alpha”, “H-beta”, “H-gamma” and so on, where H is the element hydrogen. Four of the Balmer lines are in the technically “visible” part of the spectrum, with wavelengths longer than 400 nm and shorter than 700 nm.
…
Balmer series (n′ = 2)
| n | λ, air (nm) |
|---|---|
| 7 | 397.0 |
| ∞ | 364.6 |
| Source: | |
What is H alpha line of Balmer series?
H-alpha (Hα) is a specific deep-red visible spectral line in the Balmer series with a wavelength of 656.28 nm in air; it occurs when a hydrogen electron falls from its third to second lowest energy level. H-alpha light is the brightest hydrogen line in the visible spectral range.
Which color star is hottest?
Stars have different colors, which are indicators of temperature. The hottest stars tend to appear blue or blue-white, whereas the coolest stars are red.
What determines a star’s lifespan?
A star’s life cycle is determined by its mass. The larger its mass, the shorter its life cycle. A star’s mass is determined by the amount of matter that is available in its nebula, the giant cloud of gas and dust from which it was born.
How are Balmer absorption lines produced?
In the simplified Rutherford Bohr model of the hydrogen atom, the Balmer lines result from an electron jump between the second energy level closest to the nucleus, and those levels more distant. … The 3→2 transition depicted here produces H-alpha, the first line of the Balmer series.
How were spectral types originally ordered?
Stellar spectral types originally followed alphabetical order. … In 1866, Angelo Secchi, a Jesuit astronomer working at the Vatican Observatory, surveyed some 4,000 stars and classified them by the visual appearance of their spectra. He divided stars into four broad, numbered categories based on common spectral features.
What color is the coolest star?
Red stars are the coolest. Yellow stars are hotter than red stars. White stars are hotter than red and yellow. Blue stars are the hottest stars of all.
What do spectral lines tell us?
From spectral lines astronomers can determine not only the element, but the temperature and density of that element in the star. The spectral line also can tell us about any magnetic field of the star. The width of the line can tell us how fast the material is moving. We can learn about winds in stars from this.