how old are the stars we see today

Introduction

The age of stars we observe today varies significantly, ranging from very young stars still in their formative stages to ancient stars that have existed since the early universe. Understanding the age of these stars provides insights into the history and evolution of the cosmos.

Key Insights

Young Stars and Pre-Main-Sequence Stars:
- Pre-main-sequence stars in young clusters are older than previously thought, with revised ages being 1.5-2 times longer than commonly used estimates.
- Extremely young stars, particularly those that have not yet reached the zero-age main sequence, are still in their gravitational contraction phase.
Old Star Clusters:
- The mean age of open clusters in the FSR sample is around 1 billion years, with older clusters typically found further from the Galactic center.
- Globular clusters, some of the oldest star systems, have revised ages of approximately 12 billion years, aligning with the updated age of the universe.
Ancient Stars and the Early Universe:
- Some of the oldest stars in our galaxy are over 13 billion years old, formed shortly after the galaxy itself.
- The first observable stars in the universe likely formed around 30 million years after the Big Bang.
- The age of the oldest stars is estimated to be between 12 to 15 billion years, with some estimates extending up to 17-18 billion years.
Stellar Metamorphosis Theory:
- According to the Stellar Metamorphosis theory, the Sun is relatively young at about 65 million years old, with stars' ages determined by their luminosity and activity levels .

Conclusion

The stars we see today span a wide range of ages. Young stars, including pre-main-sequence stars, are older than previously estimated, while ancient stars, such as those in globular clusters, are around 12 billion years old. Some of the oldest stars in our galaxy date back over 13 billion years, formed shortly after the Big Bang. The Stellar Metamorphosis theory presents an alternative view, suggesting much younger ages for stars based on their luminosity. Overall, the age of stars provides a window into the history and evolution of the universe.

How old are the stars we see today

Summary

Introduction

Key Insights

Conclusion

Sources and full results

Are pre-main-sequence stars older than we thought?

Pre-main-sequence stars are 1.5-2 times older than commonly thought, explaining discrepancies in protoplanetary disc lifetimes and cluster ages.

Old star clusters in the FSR catalogue

Old star clusters in the FSR sample have a mean age of 1 Gyr, with 80 percent older than 1 Gyr having a Galactocentric distance of more than 7 kpc, and a strong selection bias towards objects with an apparent core radius of 30-50 arcsec.

Determination of ages of star clusters

The color magnitude diagram (CMD) method can accurately determine the ages of star clusters like NGC 188 and M41, revealing their ages to be 4 0.5 billion years and 22030 million years respectively.

Stellar Metamorphosis: The Sun's True Age

The Sun is roughly 65 million years old, and its age can be determined by its activity, making it a relatively young star compared to older stars like Jupiter and Saturn.

Determining the Ages of Stars Mathematically Using Luminosity

Stars with a bolometric luminosity of 1/729 the Sun are about 263 million years old, and all visible stars in the sky are very young, not older than 263 million years.

The Universe Shows Its Age

The universe's age is now approaching 12 billion years, with improved theoretical models and data from the European Space Agency's Hipparcos satellite reducing the ages of ancient star systems.

Galaxy's Oldest Stars Shed Light on Big Bang

The oldest stars in our galaxy, some more than 13 billion years old, can serve as time capsules for studying the Big Bang's primordial star composition.

The first stars in the Universe

The first observable star likely formed 30 million years after the big bang, and the first galaxy as massive as our Milky Way likely formed when the Universe was only 400 Myr old.

Extremely Young Stars

Extremely young stars are those that have not yet reached the age zero main sequence, gravitationally contracting stars, and are characterized by short evolutionary ages.

The oldest stars and the age of the Universe

The age of the oldest stars is converging on 12 to 15 thousand million years, but uncertainties remain, and improvements in this situation are expected from 8-1m telescopes and space missions in the next decade.

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