As the title says, i'm interested in the precision a Doppler shift can be revealed.(adsbygoogle = window.adsbygoogle || []).push({});

That's why I read that it's possible to detect exo-planets by measuring the Doppler shift of the star's spectra. Works like this: the stars moves, since it moves back and forth is spectrum suffer from Doppler shift, by measuring this shift you can deduce at which speed the star is moving.

Now, my professor said once that state of the art spectrographs can measure the star moving at 10 cm/s.

But, using Doppler's law: [itex]V = c \frac{\lambda -\lambda_0}{\lambda_0} \qquad \Rightarrow \qquad \Delta \lambda = \frac{\lambda_0 V}{c}[/itex] and setting, for now, [itex]V = 1 m/s[/itex], [itex]c = 3 \cdot 10^{8} m/s[/itex] that means that we can reveal a [itex]\Delta \lambda = \frac{\lambda_0}{10^8}[/itex].

My professer intended that they use a special tecnique to achieve this precision and that he would probably ask me this at my exam (which is tomorrow) so please, if someone could answer very fast i would be very grateful.

**Physics Forums - The Fusion of Science and Community**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Precision in Doppler shift

Loading...

Similar Threads - Precision Doppler shift | Date |
---|---|

B Quantisation of light and Doppler effect | Dec 15, 2016 |

Why low precision of the radius of Sun's orbit in MW? | Oct 30, 2015 |

What's the precise relationship between Mass and Charge | Apr 19, 2012 |

Accepted (precise!) value for lunar L2 point? | Jan 1, 2011 |

Precisely or astronomical observation of Schulze and Taylor. | Aug 30, 2010 |

**Physics Forums - The Fusion of Science and Community**