by Ann » Sun Oct 18, 2020 5:44 am
neufer wrote: ↑Sat Oct 17, 2020 10:46 pm
https://en.wikipedia.org/wiki/F-type_main-sequence_star wrote:
<<An F-type main-sequence star is a main-sequence, hydrogen-fusing compact star of spectral type F and luminosity class V. These stars have from 1.0 to 1.4 times the mass of the Sun and surface temperatures between 6,000 and 7,600 K. This temperature range gives the F-type stars a yellow-white hue. Because a main-sequence star is referred to as a dwarf star, this class of star may also be termed a yellow-white dwarf (so as not to be confused with actual white dwarfs).>>
A famous example is Procyon A which has a color index of 0.42, and its hue has been described as having a faint yellow tinge to it.
![Procyon Akira Fuji.png](./download/file.php?id=38077&sid=b1fbb5c314fb758889824a9c6659dc09)
- Procyon Akira Fuji.png (33.25 KiB) Viewed 6019 times
You call that yellow-white????? 🡆 🡆 🡆
54 out of the 93 brightest-looking stars in the sky belong to spectral classes A, B and O. They shine with a blue-white light. But because the light-sensitive rods in the human retina are very good at picking up faint blue light (and "translate it" into white light), while simultaneously the color-sensitive cones are quite bad at discerning faint blue light, blue-white starlight usually looks white to us.
27 out of the 93 brightest-looking stars in the sky belong to spectral classes K and M. The cones in our eyes is a lot better at seeing faint yellow light than faint blue light, so we usually have no trouble seeing stars of spectral classes K and M as yellow. Also, since there are usually some bright stars of spectral classes A, B or O nearby in the sky, the sheer contrast brings out the yellowish hue of the K- and M-type stars.
But since astronomers fairly long ago decided to "define" the blue-white light of Vega as "pure white", the yellow-orange light of M-type stars gets defined as "red". The yellow light of a star like Pollux gets defined as "orange". And the Sun gets defined as "yellow". Tell me, if the Sun is yellow, how come daylight is white?
And F-type stars like Procyon gets defined as
yellow-white. Give me a break. Do you realize how blue our day-light would be if the Sun suddenly took on the same color as Procyon?
Click to play embedded YouTube video.
Ann
[quote=neufer post_id=307342 time=1602974780 user_id=124483]
[quote=https://en.wikipedia.org/wiki/F-type_main-sequence_star]
[float=right][img3=Procyon (top left), Betelgeuse, and Sirius form the Winter Triangle.]https://upload.wikimedia.org/wikipedia/commons/b/b1/Hubble_heic0206j.jpg[/img3][/float]
[size=125]<<An F-type main-sequence star is a main-sequence, hydrogen-fusing compact star of spectral type F and luminosity class V. These stars have from 1.0 to 1.4 times the mass of the Sun and surface temperatures between 6,000 and 7,600 K. This temperature range gives the F-type stars a [color=#CFCF00]yellow-white hue[/color]. Because a main-sequence star is referred to as a dwarf star, this class of star may also be termed a [url=https://www.youtube.com/watch?v=0c-UIkfsk1U&t=%20110]yellow-white dwarf[/url] (so as not to be confused with actual white dwarfs).>>
A famous example is Procyon A which has a color index of 0.42, and its hue has been described as having a faint yellow tinge to it. :arrow: [/size][/quote]
[/quote]
[float=right][attachment=0]Procyon Akira Fuji.png[/attachment][/float]
You call that yellow-white????? 🡆 🡆 🡆
:facepalm:
[float=left][img3="The 25 brightest stars in the sky. Note their colors."]https://1.bp.blogspot.com/-aSm7I20tw2w/XRIvYdcuooI/AAAAAAABKUo/GZo_SAOHLMUJXk05vweaIwYQmtulDLBzQCLcBGAs/s640/25BrightestStars_Jittasaiyapan_1500.jpg[/img3][/float]
[b][color=#0080FF]54 out of the 93 brightest-looking stars in the sky belong to spectral classes A, B and O[/color][/b]. They shine with a blue-white light. But because the light-sensitive rods in the human retina are very good at picking up faint blue light (and "translate it" into white light), while simultaneously the color-sensitive cones are quite bad at discerning faint blue light, blue-white starlight usually looks white to us.
[b][color=#FFBF00]27 out of the 93 brightest-looking stars in the sky belong to spectral classes K and M[/color][/b]. The cones in our eyes is a lot better at seeing faint yellow light than faint blue light, so we usually have no trouble seeing stars of spectral classes K and M as yellow. Also, since there are usually some bright stars of spectral classes A, B or O nearby in the sky, the sheer contrast brings out the yellowish hue of the K- and M-type stars.
But since astronomers fairly long ago decided to "define" the blue-white light of Vega as "pure white", the yellow-orange light of M-type stars gets defined as "red". The yellow light of a star like Pollux gets defined as "orange". And the Sun gets defined as "yellow". Tell me, if the Sun is yellow, how come daylight is white?
And F-type stars like Procyon gets defined as [b][color=#CFCF00]yellow-white[/color][/b]. Give me a break. Do you realize how blue our day-light would be if the Sun suddenly took on the same color as Procyon?
[float=right][youtube]https://www.youtube.com/watch?v=ANTYF6g2Q9A[/youtube][/float]
Ann