The full order of classification is O, B, A, F, G, K, M – more easily remembered by using the mnemonic “Oh Be A Fine Girl/Guy, Kiss Me”. This also orders adult (main sequence) stars from hot to cool; the hottest (and largest) main sequence stars are O and B type, while the coolest (and smallest) stars are M dwarfs.
What OBAFGKM means?
| Acronym Definition | OBAFGKM Oh, Be A Fine Girl/Guy, Kiss Me (mnemonic for the order of star temperatures) |
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What does Obafgkm stand for?
The spectral sequence O B A F G K M. The classic mnemonic is Oh Be A Fine Girl, Kiss Me . You may replace girl with guy, depending on your sexual orientation, without changing the sense of the mnemonic.
What do the spectral classes OBAFGKM indicate?
What do the initials of “OBAFGKM” mean? A: It appears that when stars were first being classified in the 1890s, an astronomer at Harvard named Edward Pickering decided to sort the stars according to how much hydrogen they contained .
What is the spectral classification OBAFGKM for a spectrum with?
| Class Spectrum Temperature | O ionized and neutral helium, weakened hydrogen above 31,000 K | A strong hydrogen, ionized metals 7100-9750 K | F weaker hydrogen, ionized metals 5950-7100 K | G still weaker hydrogen, ionized and neutral metals 5250-5950 K |
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How do you remember OBAFGKM?
- The spectral sequence O B A F G K M. ...
- The planets, in order of mean distance from the Sun, are: ...
- The colors in the rainbow (the optical spectrum), Red, Orange, Yellow, Green, Blue, Indigo, and Violet are remembered in the classic mnemonic ROY G.
What are the first stars?
Population III stars were the first suns to form in our 13.8-billion-year-old universe, and they’re identifiable by their unique composition: just hydrogen, helium and lithium, the only elements around immediately after the Big Bang. Heavier elements were forged in the cores of these stars and their successors.
What are the 7 types of stars?
There are seven main types of stars. In order of decreasing temperature, O, B, A, F, G, K, and M . This is known as the Morgan–Keenan (MK) system. The majority of all stars in our galaxy and even the Universe are main-sequence stars.
What is the biggest star?
Although it’s difficult to pin down the exact traits of any given star, based on what we know, the largest star is UY Scuti , which is some 1,700 times as wide as the Sun.
What color star is the coolest?
You can tell a lot about a star by its color. You can tell the temperature of the star. Red stars are the coolest. Yellow stars are hotter than red stars.
What spectral class of stars is the coolest?
The spectral sequence is also a colour sequence: the O- and B-type stars are intrinsically the bluest and hottest; the M-, R-, N-, and S-type stars are the reddest and coolest.
What does OH a fine girl kiss me mean?
Every student in introductory astronomy learns the mnemonic “Oh Be a Fine Girl/Guy, Kiss Me”, which is a way to remember the spectral classification of stars . ... Oh: O class stars are the hottest, with peak temperatures in the ultraviolet part of the spectrum.
Which kind of star is hottest?
The hottest stars are the blue stars . A star appears blue once its surface temperature gets above 10,000 Kelvin, or so, a star will appear blue to our eyes. So the hottest stars in the Universe are going to be a blue star, and we know they’re going to be massive.
What are the three main luminosity classes?
| Luminosity Classes | II Bright Giants Canopus (F0II) | III Giants Capella (G5III) | IV Subgiants Beta Cru (B0IV) | V Main Sequence Vega (A0V) |
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What role does hydrogen play in spectral classification?
What role does hydrogen play in spectral classification? It is most prominent in A stars, but fades at hotter or cooler temperatures . ... Contrast main sequence stars of type B and G. The B star will be hotter, larger, more massive and more luminous.
What is Harvard spectral classification?
The Harvard Spectral Classification is based on the absorption lines (i.e. bark lines) in the stellar spectrum , that are sensitive to the stellar temperature, rather than to gravity or luminosity.
