How would one estimate the rotation period of a star from its spectrum

Click For Summary
The discussion centers on estimating a star's rotation period using its spectral data, specifically observing shifts in flux due to starspots. The "bumps" in the flux profile indicate the movement of a starspot across the star's surface as it rotates. The challenge lies in correlating the observed wavelength shifts to a time scale for accurate rotational period estimation. Reference material, including a figure from Gray's work, is suggested for further understanding. The conversation emphasizes the need for a time-based analysis to derive the rotation period effectively.
SJay16
Messages
19
Reaction score
1
Homework Statement
Using the profiles in Figure 18.29, make an estimate for the rotation period of σ Gem.
Relevant Equations
N/A
Screenshot (156).png

The figure is shown; the measurements were taken on two consecutive observing nights. The Ordinate is the flux normalized to continuum and the abscissa is the wavelength scale. You can see the "bumps" indicated by the arrows referring to some Starspot as the spot moves on the profile; assuming a single time-stable position-stable spot.

The "bumps" slightly shifts, as indicated by the arrows in the top line profile compared to the bottom profile, as the spot "moves across" the surface as the star as it rotates; I'm just not sure how to get an estimate of the rotational period from this given just the wavelength for the abscissa, it would make sense if the abscissa was on a timescale.

Figure reference : Gray, D. (2005). The Observation and Analysis of Stellar Photospheres (3rd ed.), page 498. Cambridge: Cambridge University Press. doi:10.1017/CBO9781316036570
 
Physics news on Phys.org
Thread 'Earthed plates confusion'

Thread 'Earthed plates confusion'

So, we know that since the 3rd plate is grounded that means the potential from the right side of the third plate to infinity should be 0, i.e no work should be required to bring a test charge from infinity to the right side of plate 3. Similarly the left side of plate 3's potential should also be 0, i.e no work is done when moving a test charge from infinity to the left side of plate 3. This should mean the fields in these regions should either cancel out or be 0. My teacher told me that...
View full post »

Similar threads

What is GJ 1214 b: A Super-Earth Water World Orbiting a Red Dwarf Star?
  • · Replies 1 ·
Replies
1
Views
7K
I Some questions about Cosmic Microwave Background radiation
  • · Replies 13 ·
Replies
13
Views
6K
Estimating the impact of CO2 on global mean temperature
  • · Replies 89 ·
3
Replies
89
Views
37K