Talk:HR 5553
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glaring inconsistencies[edit]
the listed values for mass of the binary components of this system are inconsistent with values for semi-major axis and orbital period. running the formula from standard gravitational parameter, mu = 4 pi^2 a^3 / T^2, i get 7.72x10^18. but comparing this with the formula mu = G(M0 + M1) = 1.65 x 10^20, the discrepancy is a factor ~ 21. it doesn't help that this system is known by different names in different papers. i'm expecting there must be either an error in source material or different systems were erroneously associated with each other. 99.230.229.254 (talk) 01:00, 27 September 2019 (UTC)
- tracing this inconsistency between orbit and masses, it appears in table 1 of reference 3, Kennedy 2015, page 2, who does not derive these himself but combines values from multiple other sources:
- Jancart, S., Jorissen, A., Babusiaux, C., & Pourbaix, D. 2005, A&A, 442, 365
- Nidever, D. L., Marcy, G. W., Butler, R. P., Fischer, D. A., & Vogt, S. S. 2002, ApJS, 141, 503
- even before seeing these, as it is often problematic to combine sources consistently, I'd say there's your error -- 135.23.66.249 (talk) 12:28, 1 October 2019 (UTC)
- reading into Nidever et al's discussion of uncertainties is quite telling, [1] but doesn't appear to yield an easy way to fix the problem -- 135.23.66.249 (talk) 14:35, 1 October 2019 (UTC)
- yes it does! scroll down to Table 3 Orbital Parameters, of Nidever and you will find a(min) is listed there as 0.52 AU. much more believable, but we're not totally done. i see no value for a of 16.54±0.18 mas in Nidever but by the time this gets to Jancart et al, there it is in table 3. But did you notice that the orbital period is only 3% from a definite ratio of earth's orbital period? 365.25 days / 125.4 days = 2.913. surprise! this throws off the original parallax measurement and therefore the distance to this system is under-estimated, which affects several derived values -- 135.23.66.249 (talk) 08:39, 3 October 2019 (UTC)
- This type of discrepancy will need to be worked out in published works. WP:OR restricts us to just using data from reliable sources. Praemonitus (talk) 17:31, 7 December 2019 (UTC)
- yes it does! scroll down to Table 3 Orbital Parameters, of Nidever and you will find a(min) is listed there as 0.52 AU. much more believable, but we're not totally done. i see no value for a of 16.54±0.18 mas in Nidever but by the time this gets to Jancart et al, there it is in table 3. But did you notice that the orbital period is only 3% from a definite ratio of earth's orbital period? 365.25 days / 125.4 days = 2.913. surprise! this throws off the original parallax measurement and therefore the distance to this system is under-estimated, which affects several derived values -- 135.23.66.249 (talk) 08:39, 3 October 2019 (UTC)