2007-02-27 21:51:36 · 6 answers · asked by Bea A 1 in Science & Mathematics ➔ Astronomy & Space
The idea: It would be nice to have at least a vague idea of what color stars are.
Here is some help on converting from stellar type/class (and color indexes) to pixel rgb values.
More formally - I have derived chromaticity and rgb pixel color, from spectra for various stellar types/classes, providing physically-motivated colors for astronomy presentations. Though the colors are still a bit rough.
The colors here are for the big balls of hot gas in space, rather than the pin-pricks of light in the local sky. I.e., atmospheric, interstellar medium, and relative motion effects are discarded...
The OBAFGKM table...
Sp5(V) r g b rgb
O 155 176 255 #9bb0ff
B 170 191 255 #aabfff
A 202 215 255 #cad7ff
F 248 247 255 #f8f7ff
G 255 244 234 #fff4ea
K 255 210 161 #ffd2a1
M 255 204 111 #ffcc6f
Some familiar stars...
Sun viewed outside of atmosphere (ref) #fff3ea
Achernar (B3V)
#a5b9ff
Acrux (B0IV)
#9cb2ff (as B0V)
Adhara (B2II)
#a5c0ff
Aldebaran (K5III)
#ffcc8a
Alnilam (B0I)
#a1bdff
Alpha Centari A (G2V)
#fff5f2
Alpha Centari B (K1V)
#ffe0bc
Altair (A7V)
#c8d5ff
Antares (M1I)
#ffca8a
Arcturus (K1III)
#ffdfb5
Bellatrix (B2III)
#9fb4ff
Beta Centari
Hadar (B1III)
#9eb1ff
Beta Crucis (B0III)
#9eb1ff
Betelgeuse (M1I)
#ffca8a
Canopus (F0II)
#cbd9ff
Capella (G5III)
#ffecd3
Deneb (A2I)
#c7d6ff
Elnath (B7III)
#abbfff
Fomalhaut (A3V)
#bfcfff
Gacrux (M3III)
#ffc877
Miaplacidus (A2IV)
#bbcbff (as A2V)
Pollux (K0III)
#ffe3be
Procyon (F5IV)
#f1efff
Regulus (B7V)
#adbfff
Rigel (B8I)
#b6ceff
Shaula (B2IV)
#9fb3ff
Sirius (A1V)
#b5c7ff
Spica (B1III)
#9eb1ff
Sun (G2V)
#fff5f2
Vega (A0V)
#b9c9ff
[Type/class data from Bright Star Catalog bsc5p.]
Some nearby stars...
Sun (G2V)
#fff5f2
Alpha Centauri A (G2V)
#fff5f2
Alpha Centauri B (K0V)
#ffeedd
Proxima Centauri (M5.5V)
#ffcc6f (as M5V)
Barnard's Star (M4.0V)
#ffc97f
Wolf 359 (M6.0V)
#ffc370
Lalande 21185 (M2.0V)
#ffc483
Sirius (A1V)
#b5c7ff
Sirius B (DA2)
#a8bdff (as D?2)
UV Ceti A (M5.5V)
#ffcc6f (as M5V)
UV Ceti B (M6.0V)
#ffc370
Ross 154 (M3.5V)
#ffce81 (as M3V)
Ross 248 (M5.5V)
#ffcc6f (as M5V)
epsilon Eridani (K2V)
#ffe3c4
Lacaille 9352 (M1.5V)
#ffcc8e (as M1V)
Ross 128 (M4.0V)
#ffc97f
EZ Aquarii (M5.0V)
#ffcc6f
Procyon (F5IV-V)
#f1efff (as F5IV)
61 Cygni (K5.0V)
#ffd2a1
61 Cygni B (?) (K7.0V)
#ffc78e
Gl 725 A (M3.0V)
#ffce81
Gl 725 B (M3.5V)
#ffce81 (as M3V)
Gl 15 A (M1.5V)
#ffcc8e (as M1V)
Gl 15 B (M3.5V)
#ffce81 (as M3V)
epsilon Indi (K5Ve)
#ffd2a1 (as K5V)
DX Cancri (M6.5V)
#ffc370 (as M6V)
tau Ceti (G8Vp)
#ffedde (as G8V)
RECONS 1 (M5.5V)
#ffcc6f (as M5V)
YZ Ceti (M4.5V)
#ffc97f (as M4V)
Luyten's Star (M3.5V)
#ffce81 (as M3V)
Kapteyn's Star (M1.5V)
#ffcc8e (as M1V)
[Type/class data from THE 100 NEAREST STAR SYSTEMS. Here is a hack colorized version. ]
Yes, to a zeroth approximation, all stars are type M :).
Hmm... so is Alpha Cent B a K0V or a K1V??
Stellar types
O5(V) 157 180 255 #9db4ff
B1(V) 162 185 255 #a2b9ff
B3(V) 167 188 255 #a7bcff
B5(V) 170 191 255 #aabfff
B8(V) 175 195 255 #afc3ff
A1(V) 186 204 255 #baccff
A3(V) 192 209 255 #c0d1ff
A5(V) 202 216 255 #cad8ff
F0(V) 228 232 255 #e4e8ff
F2(V) 237 238 255 #edeeff
F5(V) 251 248 255 #fbf8ff
F8(V) 255 249 249 #fff9f9
G2(V) 255 245 236 #fff5ec
G5(V) 255 244 232 #fff4e8
G8(V) 255 241 223 #fff1df
K0(V) 255 235 209 #ffebd1
K4(V) 255 215 174 #ffd7ae
K7(V) 255 198 144 #ffc690
M2(V) 255 190 127 #ffbe7f
M4(V) 255 187 123 #ffbb7b
M6(V) 255 187 123 #ffbb7b
See Star color - details for greater detail.
These are not "magic" pixel values. Different approaches yield different values, but ones with quite similar appearance.
Other
Planetary Nebula 0.1378 0.3817 000 255 236 #00ffec Kurucz
Galaxy (spiral) 0.3523 0.3556 255 225 199 #ffe1c7 Kurucz
Galaxy (elliptical) 0.3617 0.3649 255 222 186 #ffdeba Kurucz
Quasar 0.2188 0.2764 073 214 255 #49d6ff Kurucz
Universe 0.3450 0.3450 255 225 209 #ffe1d1 Glazebrook & Baldry
Notes
So, what should be born in mind looking at these colors?
These colors attempt to show "true" color. That is: without intervening atmosphere or interstellar medium; with the light dim enough to avoid saturating your cones (which would make the light appear white); and yet with the light bright enough that you are seeing color rather than rod grayscale.
So... looking at the star from space while wearing gray sunglasses (unpolarized:). Hmm... or better, through a gray window shade in a D65 white wall.
In applying these colors, remember that color perception is quite messy, so what you see is often not what you've got.
This page is concerned only with chromaticity (hue and saturation), but not brightness. The luminous power per unit area of star classes varies greatly. If we were doing brightness, and the G class star color were as above, then the M class star color would simply be black. See Blackbody colors - intensity.
The choice of white point, used in converting from abstract chromaticity to device-dependent rgb, has a large effect. Eg, see Sun. These colors use D65. I plan to add a set for D50.
Are you sure these colors are right? They seem odd.
No, I am not sure. And yes, they do. I was expecting rather different colors. As are many other folk, apparently, from my reading. Nevertheless...
Links
2007-02-27 21:55:47 · answer #1 · answered by genius_06 3 · 0⤊ 0⤋
The hoter the star's temperature, the farther along the color line the star will be. Think of an iron bar being heated by a torch: as it begins to heat the color turns red. Higher temperature causes a yellow color. As more heat is applied it turns white, and then blue-white.
The larger a star, the brighter it will be.
Light a single match and estimate its brightness in the dark. Light an entire box of matches and estimate the brightness again. Which was brighter, the smaller or the larger?
2007-03-03 15:01:54 · answer #2 · answered by NJGuy 5 · 0⤊ 0⤋
It depends on the age of the star. If the star has just been born it will be very bright and will be blue or white. If the star is middle aged like our sun, it will not be so bright and will be yellow. If it is old and is going to die it will not be bright and will be red in colour.
2007-02-27 22:04:34 · answer #3 · answered by sanjay_tandon9 2 · 0⤊ 0⤋
The color of a star as a function of its radiation and related to its temperature; colors range from blue-white to deep red. Bright stars are bright because they have high luminosities and/or they are nearby.
2007-02-27 21:59:48 · answer #4 · answered by Sherwin R 2 · 0⤊ 0⤋
distance and SIZE = brightness of the star
gas or gasses it releases or what it is made of = colors of the star.
2007-02-27 21:54:03 · answer #5 · answered by Anonymous · 0⤊ 0⤋
sun light
2007-02-27 21:55:44 · answer #6 · answered by booge 6 · 0⤊ 0⤋