Hydrogen lines are strongest in A stars with atmospheric temperatures of about 10,000 K. Ionized metals provide the most conspicuous lines in stars with temperatures from 6000 to 7500 K (spectral type F). In the coolest M stars (below 3500 K), absorption bands of titanium oxide and other molecules are very strong.
What is the wavelength of the strongest hydrogen absorption line?
You would see the strongest hydrogen lines for a cloud that is at about 9000 K.
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.
Which spectral class has strong hydrogen Balmer lines and weak ionized calcium spectral lines?
Class A stars are noted for their distinct Balmer lines of Hydrogen, while G stars begin exhibiting strong lines due to ionized metals, which take less energy to ionized.
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| Spectral Class | Surface Temp | Prominent Absorption Lines |
|---|---|---|
| M | 3,000 K | very faint Hydrogen; strong neutral heavy elements; moderate strength molecules |
Which stellar spectral type has strong molecular absorption lines?
Cards
| Term Which stellar spectral type has strong molecular absorption lines in its optical spectrum? | Definition M |
|---|---|
| Term The total amount of power that a star radiates into space is called its | Definition luminosity |
| Term Our Sun is a star of spectral type | Definition G |
Why does the sun’s corona show emission lines?
The corona shines brightly in x-rays because of its high temperature. On the other hand, the “cool” solar photosphere emits very few x-rays. This allows us to view the corona across the disk of the Sun when we observe the Sun in X-rays.
What spectral class has the strongest Balmer lines?
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.
Why do the coolest stars show weak Balmer lines?
Since the Balmer series lines require electrons to already be in level 2, if there are no hydrogen electrons in level 2 in the gas, there will not be any Balmer series hydrogen lines created by that gas. So, very cool stars will have weak Balmer series hydrogen lines, too.
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.
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 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.
Which star has the highest surface temperature?
Type O stars have the highest surface temperatures and can be as hot as 30,000 Kelvins.
What are the 7 spectral classes in order from hottest to coolest?
From hottest to coldest, these seven spectral classes are designated O, B, A, F, G, K, and M. Recently, astronomers have added three additional classes for even cooler objects—L, T, and Y.
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 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 is the Harvard classification of stellar spectra?
Harvard spectral classification
| Class | Effective temperature | Main-sequence luminosity (bolometric) |
|---|---|---|
| B | 10,000–30,000 K | 25–30,000 L ☉ |
| A | 7,500–10,000 K | 5–25 L ☉ |
| F | 6,000–7,500 K | 1.5–5 L ☉ |
| G | 5,200–6,000 K | 0.6–1.5 L ☉ |