Undergrad Calculating semi-major axis and minimum mass of an exoplanet

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SUMMARY

The discussion focuses on calculating the semi-major axis and minimum mass of an exoplanet using Kepler's third law. The stellar mass is given as 1.31 ± 0.05 Msun, with an orbital period of 2.243752 ± 0.00005 days and a radial velocity semi-amplitude of 993.0 ± 3 m/s. The derived semi-major axis is 5.49042 x 10^9 m (0.037 AU) and the minimum mass is 1.46082 x 10^28 kg (7.696 Mjupiter). The participant seeks assistance in determining the uncertainties associated with these calculations.

PREREQUISITES
  • Understanding of Kepler's third law of planetary motion
  • Familiarity with gravitational constant (G = 6.67408 × 10^-11 m³ kg^-1 s^-2)
  • Basic knowledge of calculating uncertainties in measurements
  • Experience with astronomical mass units (e.g., Msun, Mjupiter)
NEXT STEPS
  • Learn how to calculate uncertainties in derived quantities
  • Study the application of Kepler's laws in exoplanet detection
  • Explore the significance of radial velocity methods in exoplanet studies
  • Investigate the relationship between orbital period and semi-major axis in detail
USEFUL FOR

Astronomy students, astrophysicists, and anyone involved in exoplanet research or calculations related to orbital mechanics.

Mauro Montemayor
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Hello guys,

I'm doing my physics coursework on kepler's third law and I'm finding the minimum mass and semi-major axis of a unknown planet. I have the following data:

Stellar mass Mstar = 1.31 ± 0.05 Msun

Orbital period P = 2.243752 ± 0.00005 days

Radial velocity semi-amplitude: V = 993.0 ± 3 m/s

Inclination i = 84.32º ± 0.67

We assume eccentricity e=0

Gravitational constant, G=6.67408 × 10-11 m3 kg-1 s-2

Jupiter mass: Mj=1,898 × 10^27 kg

From this I found that,
semi-major axis = 5.49042 x 10^9 m = 0.037 AU
Minimum mass = 1.46082 x 10^28 kg = 7.696 Mjupiter

The results are correct. However, I am not able to find the uncertainties of these two values. I would appreciate some help with this matter.

Thank you,

Mauro
 
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Hi Mauro:

If you show the actual calculations that you used to derive semi-major axis and Minimum mass, I think that I can show you how to calculate the uncertainties.

Regards,
Buzz
 

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