---

Spectroscopic Parallax

---

Astronomers use the information in the HR Diagram to find the distance to stars too far away to measure the parallax angle.

This is not a real parallax. It is a way of estimating distances. This is an example of the Standard Candle Method.

• Measure the brightness of the star
• Classify the spectra of the star (OBAFGKM)
• Use the HR Diagram to infer the luminosity of the star
• Use the inverse square law to calculate the distance to the star

We are now building up a distance ladder to measure distances to objects farther and farther away...