Hipparcos

Definition

Hipparcos is a satellite mission launched by the European Space Agency in 1989, designed for astrometric measurements to determine the positions, distances, and motions of stars with exceptional accuracy. The data collected by Hipparcos significantly improved our understanding of stellar distances and provided key insights into the Cosmic Distance Ladder, allowing astronomers to better calibrate standard candles like Cepheid variables and Type Ia supernovae.

5 Must Know Facts For Your Next Test

1. Hipparcos provided precise measurements for over 118,000 stars, including their positions and brightness, which helped refine distance measurements across the galaxy.
2. The data from Hipparcos allowed for the first comprehensive three-dimensional map of the Milky Way, highlighting the distribution of stars in our galaxy.
3. By measuring parallax shifts, Hipparcos reduced the uncertainties in distance calculations by a factor of 10 compared to previous methods.
4. The mission completed its primary objective in 1993 but continued to provide valuable data until its final re-entry into Earth's atmosphere in 2010.
5. The results from Hipparcos have had lasting impacts on various fields of astrophysics, including star formation studies, galactic dynamics, and the determination of the Hubble constant.

Review Questions

• How did the Hipparcos mission contribute to improving measurements of stellar distances and motions?
  • The Hipparcos mission utilized advanced astrometric techniques to measure the positions and motions of over 118,000 stars with unprecedented precision. By applying parallax methods, Hipparcos was able to reduce uncertainties in distance measurements significantly. This improvement allowed astronomers to create a more accurate three-dimensional map of the Milky Way and enhanced our understanding of stellar evolution and dynamics.
• Discuss the role of Hipparcos data in calibrating standard candles used in distance measurement within the universe.
  • The data obtained from the Hipparcos mission were essential for calibrating various standard candles, such as Cepheid variables and Type Ia supernovae. By providing accurate distances to these objects, Hipparcos allowed astronomers to establish a reliable relationship between their intrinsic brightness and observed brightness. This calibration is crucial for measuring vast cosmic distances and understanding the expansion of the universe.
• Evaluate the long-term implications of the Hipparcos mission's findings on modern astrophysics and cosmology.
  • The findings from the Hipparcos mission have had profound implications for modern astrophysics and cosmology. By delivering precise measurements that refined our understanding of stellar distances and motions, it influenced key areas such as galaxy formation, dynamics, and even the determination of cosmological parameters like the Hubble constant. The legacy of Hipparcos continues to shape astronomical research today, guiding new missions and studies that build upon its foundational data.

Related terms

Parallax: The apparent shift in position of a nearby star against a distant background star, used to measure stellar distances through triangulation.

Standard Candles: Astronomical objects with known luminosity, used to measure distances in the universe based on their brightness as observed from Earth.

Cepheid Variables: A type of pulsating star whose brightness varies periodically, making them useful as standard candles for measuring cosmic distances.