<p>Surely this is exactly what the V-band bolometric correction assesses. The numerically larger the bolometric correction, the more of a star's flux (as a fraction) is in the V-band.</p>

<p>The Sun's bolometric correction is about -0.06 to -0.11 mag, depending on which sources you look at. Cool stars and hot stars have numerically smaller BCs and emit a bigger fraction of their flux outside the V band.</p>

<p>Some sources put the BCs of A5-G0 stars as very slightly larger than the Sun's, by up to 0.1 mag (e.g. <a href="https://arxiv.org/abs/1307.2657" rel="nofollow noreferrer">Pecaut &amp; Mamajek 2013</a>).</p>

CC BY-SA 4.0
2020-01-28T05:44:32.147Z
[don't call me Shirley!](https://youtu.be/KM2K7sV-K74)
uhoh
CC BY-SA 4.0
2020-01-27T22:42:16.967Z
2020-01-27T22:42:16.967Z
ProfRob
<p>If one sets both the bolometric and visual luminosity of the Sun to 1 (and use a linear scale), can a star then have a higher visual than bolometric luminosity?</p>

<p>It makes sense that this will not be the case for <em>most</em> stars, as smaller stars will tend to radiate more of their energy as infrared, while larger go more into the ultraviolet. That is, this is inherently linked to what wavelengths the human eye has evolved sensitivity for. But are there exceptions? If there are, I would think they have parameters very close to the sun.</p>

CC BY-SA 4.0
2020-01-26T20:04:21.590Z
The luminosity through any filter, or limited wavelength range, can ever be only a fraction of the total luminosity. So no.
AtmosphericPrisonEscape
CC BY-SA 4.0
2020-01-26T21:23:49.890Z
@AtmosphericPrisonEscape This is for normalised values, so the filtered wavelength range's fraction of sunlight is set to 1.
SE - stop firing the good guys
CC BY-SA 4.0
2020-01-27T10:31:35.497Z
So basically you're asking "Can a star emit a larger fraction of its total light in the visual that the Sun does"? The answer would depend on your exact definition of the V filter (i.e. width, central wavelength, and shape). Or maybe you're not interested in astronomical filters, but in the response function of the cones of the eye. I suppose the answer is "Yes, but the Sun is pretty close to maximal value in the visual". But we have probably evolved to maximal response of _sunlight through the atmosphere_, which is slightly more yellow than the Sun's intrinsic color.
pela
CC BY-SA 4.0
2020-01-27T11:12:29.990Z
@pela Exactly. Your way of putting it is much clearer, so I will edit the title.
SE - stop firing the good guys
CC BY-SA 4.0
2020-01-27T11:25:14.373Z
It is also worth noting that blackbody spectra at higher temperature have more power at all frequencies than blackbodies of a lower temperature, so the two ways for the answer to the question to be yes would be (1) better centred in the visible light range, or (2) having enough absorption to tweak the spectrum. Both cases sound like they would have to be very close to the solar spectrum unless there is a way of getting really wild absorption, which seems unlikely.
Anders Sandberg
<luminosity><visible-light>
Can a star emit a larger fraction of its total light in the visual range than the Sun does
SE - stop firing the good guys
# Can a star emit a larger fraction of its total light in the visual range than the Sun does

(Asked by: username_0 on 2020-01-26)

If one sets both the bolometric and visual luminosity of the Sun to 1 (and use a linear scale), can a star then have a higher visual than bolometric luminosity?

It makes sense that this will not be the case for *most* stars, as smaller stars will tend to radiate more of their energy as infrared, while larger go more into the ultraviolet. That is, this is inherently linked to what wavelengths the human eye has evolved sensitivity for. But are there exceptions? If there are, I would think they have parameters very close to the sun.

**Tags:** luminosity, visible-light

> **Comments:**
> **username_1**: The luminosity through any filter, or limited wavelength range, can ever be only a fraction of the total luminosity. So no.  
> **username_0**: @username_1 This is for normalised values, so the filtered wavelength range's fraction of sunlight is set to 1.  
> **username_2**: So basically you're asking "Can a star emit a larger fraction of its total light in the visual that the Sun does"? The answer would depend on your exact definition of the V filter (i.e. width, central wavelength, and shape). Or maybe you're not interested in astronomical filters, but in the response function of the cones of the eye. I suppose the answer is "Yes, but the Sun is pretty close to maximal value in the visual". But we have probably evolved to maximal response of _sunlight through the atmosphere_, which is slightly more yellow than the Sun's intrinsic color.  
> **username_0**: @username_2 Exactly. Your way of putting it is much clearer, so I will edit the title.  
> **username_3**: It is also worth noting that blackbody spectra at higher temperature have more power at all frequencies than blackbodies of a lower temperature, so the two ways for the answer to the question to be yes would be (1) better centred in the visible light range, or (2) having enough absorption to tweak the spectrum. Both cases sound like they would have to be very close to the solar spectrum unless there is a way of getting really wild absorption, which seems unlikely.  

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## 1 answers

### Answer by username_4 on 2020-01-27. Score: 4 | Accepted answer

Surely this is exactly what the V-band bolometric correction assesses. The numerically larger the bolometric correction, the more of a star's flux (as a fraction) is in the V-band.

The Sun's bolometric correction is about -0.06 to -0.11 mag, depending on which sources you look at. Cool stars and hot stars have numerically smaller BCs and emit a bigger fraction of their flux outside the V band.

Some sources put the BCs of A5-G0 stars as very slightly larger than the Sun's, by up to 0.1 mag (e.g. [Pecaut & Mamajek 2013](https://arxiv.org/abs/1307.2657)).

> **Comments:**
> **username_5**: [don't call me Shirley!](https://youtu.be/KM2K7sV-K74)  

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