Stellar Color Index and Blackbody Spectrum
This tool computes stellar and planetary temperatures and radiation in the simplified case where the stars are main sequence and the planets are airless, fast-rotating black bodies.
There are presets for local stars and known planets orbiting those stars where the orbital radius is known. Selecting one of these presets enters data in three of the four user-settable parameters, although it also sets the albedo to Earth average (here, assumed to be 0.3). The two stellar parameters are B-V color index and absolute bolometric magnitude. The first (B-V) is the difference between how the star looks through two different filters (blue and visible). Mbol is the absolute bolometric magnitude which gives the total energy emitted by a star, excluding neutrinos. From these, the radius, surface temperature and approximate blackbody spectrum of the star can be calculated, which are shown in the annotation and illustration immediately below with a spectrum charted at the end.
The second pair of inputs has to do with a real or hypothetical planet in orbit at a given distance from the star that was configured in the preceding section. The distance from the star is entered in astronomical units, AU, which is the mean Earth-Sun distance. Albedo determines how much of the incoming stellar energy is reflected by the planet, leaving 1-albedo as radiation absorbed the surface. In the case where a planet is located in a multi-star system, only the radiation from the star to which it is bound is computed.
Important caveats: The albedo is assumed to be due to surface reflection and not, as is the case with Earth or Venus, primarily due to clouds. Planets are modeled as airless black bodies and so posess no greenhouse effect. They are assumed to rotate rapidly so that heat incident on the star-side is emitted equally over the whole surface. As anyone who's ever been in a desert during a hot day can attest, the temperature can drop rapidly during the night and even get below freezing, so this is a crude approximation, and especially so for Mars.
There are presets for local stars and known planets orbiting those stars where the orbital radius is known. Selecting one of these presets enters data in three of the four user-settable parameters, although it also sets the albedo to Earth average (here, assumed to be 0.3). The two stellar parameters are B-V color index and absolute bolometric magnitude. The first (B-V) is the difference between how the star looks through two different filters (blue and visible). Mbol is the absolute bolometric magnitude which gives the total energy emitted by a star, excluding neutrinos. From these, the radius, surface temperature and approximate blackbody spectrum of the star can be calculated, which are shown in the annotation and illustration immediately below with a spectrum charted at the end.
The second pair of inputs has to do with a real or hypothetical planet in orbit at a given distance from the star that was configured in the preceding section. The distance from the star is entered in astronomical units, AU, which is the mean Earth-Sun distance. Albedo determines how much of the incoming stellar energy is reflected by the planet, leaving 1-albedo as radiation absorbed the surface. In the case where a planet is located in a multi-star system, only the radiation from the star to which it is bound is computed.
Important caveats: The albedo is assumed to be due to surface reflection and not, as is the case with Earth or Venus, primarily due to clouds. Planets are modeled as airless black bodies and so posess no greenhouse effect. They are assumed to rotate rapidly so that heat incident on the star-side is emitted equally over the whole surface. As anyone who's ever been in a desert during a hot day can attest, the temperature can drop rapidly during the night and even get below freezing, so this is a crude approximation, and especially so for Mars.
Stellar Color Index and Blackbody Spectrum copyright (C) Neon Media, LLC.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL NEON MEDIA, LLC, ITS PARTNERS, EMPLOYEES, OR ASSIGNS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
Portions (D3.js and D3-format.js) copyright (C) 2010-2016, Michael Bostock. All rights reserved.
Redistribution and use (of D3.js and D3-format.js) in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
* The name Michael Bostock may not be used to endorse or promote products derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MICHAEL BOSTOCK BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL NEON MEDIA, LLC, ITS PARTNERS, EMPLOYEES, OR ASSIGNS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
Portions (D3.js and D3-format.js) copyright (C) 2010-2016, Michael Bostock. All rights reserved.
Redistribution and use (of D3.js and D3-format.js) in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
* The name Michael Bostock may not be used to endorse or promote products derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MICHAEL BOSTOCK BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.