<p>As it will explode this year or so, I became interested in the binary T Coronae Borealis. According to wikipedia, <a href="https://en.wikipedia.org/wiki/T_Coronae_Borealis" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/T_Coronae_Borealis</a>  <a href="https://en.wikipedia.org/wiki/T_Coronae_Borealis" rel="nofollow noreferrer">R Cor Bor</a> the binary masses are 1.34 and 1.15 solar masses, being separated 0.54 AU. Plugging these data into the Kepler third law, I can not get the period given by 228 days as obtained by spectroscopy from the bibliography therein. Even if I play with the binary mass function I can not get the 228 days. Are some of the wikipedia data wrong?</p>

CC BY-SA 4.0
2024-03-23T21:20:55.203Z
Did you also test with the given mass uncertainties? With 1.37+-0.13 Msun and 1.12+-0.23 Msun they are quite significant. The period is measured, the masses inferred
planetmaker
CC BY-SA 4.0
2024-03-23T22:28:55.943Z
0.3 solar masses (combining your given error in quadrature) seems to me not to provide too much error. I also tested the formula with the radial velocity and the period is not the one got from measurement. What is more likely to be wrong? Masses ...or the orbital separation? After all 0.54 AU seems also imprecise with 2 significant figures as well...
riemannium
CC BY-SA 4.0
2024-03-23T22:32:29.153Z
@planetmaker I plugged the period and the given orbital separation, major semi-axis, and I got 0.4 solar masses, that seems to be completely wrong. Also, I decided to test the orbital inclination...but it should be very different to the provided i=67º also derived from measurements for the system. What is happening here?
riemannium
CC BY-SA 4.0
2024-03-23T22:52:59.323Z
I am beggining to think that the mistake could be the orbital separation. Here, https://arxiv.org/pdf/0903.1349v1.pdf, the a in solar radius is 208 solar radii, that with Kepler third law provides about 220 days, closer to the measured period...
riemannium
CC BY-SA 4.0
2024-03-24T03:51:12.140Z
Did you mean to link another paper? Separation is given as a sin i =0.4998±0.0035 AU. https://arxiv.org/pdf/1909.13858.pdf
planetmaker
<binary-star><keplers-laws>
T Coronae Borealis
riemannium
# T Coronae Borealis

(Asked by: username_0 on 2024-03-23)

As it will explode this year or so, I became interested in the binary T Coronae Borealis. According to wikipedia, <https://en.wikipedia.org/wiki/T_Coronae_Borealis> [R Cor Bor](https://en.wikipedia.org/wiki/T_Coronae_Borealis) the binary masses are 1.34 and 1.15 solar masses, being separated 0.54 AU. Plugging these data into the Kepler third law, I can not get the period given by 228 days as obtained by spectroscopy from the bibliography therein. Even if I play with the binary mass function I can not get the 228 days. Are some of the wikipedia data wrong?

**Tags:** binary-star, keplers-laws
> **Comments:**
> **username_1**: Did you also test with the given mass uncertainties? With 1.37+-0.13 Msun and 1.12+-0.23 Msun they are quite significant. The period is measured, the masses inferred  
> **username_0**: 0.3 solar masses (combining your given error in quadrature) seems to me not to provide too much error. I also tested the formula with the radial velocity and the period is not the one got from measurement. What is more likely to be wrong? Masses ...or the orbital separation? After all 0.54 AU seems also imprecise with 2 significant figures as well...  
> **username_0**: @planetmaker I plugged the period and the given orbital separation, major semi-axis, and I got 0.4 solar masses, that seems to be completely wrong. Also, I decided to test the orbital inclination...but it should be very different to the provided i=67º also derived from measurements for the system. What is happening here?  
> **username_0**: I am beggining to think that the mistake could be the orbital separation. Here, https://arxiv.org/pdf/0903.1349v1.pdf, the a in solar radius is 208 solar radii, that with Kepler third law provides about 220 days, closer to the measured period...  
> **username_1**: Did you mean to link another paper? Separation is given as a sin i =0.4998±0.0035 AU. https://arxiv.org/pdf/1909.13858.pdf  

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## 0 answers

