Search results
Results From The WOW.Com Content Network
Bartholomeus Jan "Bart" Bok (April 28, 1906 – August 5, 1983) was a Dutch-American astronomer, teacher, and lecturer.He is best known for his work on the structure and evolution of the Milky Way galaxy, and for the discovery of Bok globules, which are small, densely dark clouds of interstellar gas and dust that can be seen silhouetted against brighter backgrounds.
The star is moving closer to the Sun with a radial velocity of −11 km/s, [5] and is traversing the sky with a relatively high proper motion of 0.271 arc seconds per year. [ 11 ] Eta Ursae Minoris is about one billion years old and has an estimated 1.35 times the mass of the Sun . [ 7 ]
The following is a list of astronomers, astrophysicists and other notable people who have made contributions to the field of astronomy.They may have won major prizes or awards, developed or invented widely used techniques or technologies within astronomy, or are directors of major observatories or heads of space-based telescope projects.
The age of the oldest known stars approaches the age of the universe, about 13.8 billion years. Some of these are among the first stars from reionization (the stellar dawn), ending the Dark Ages about 370,000 years after the Big Bang. [1] This list includes stars older than 12 billion years, or about 87% of the age of the universe.
Since more massive stars use their fusion fuel more quickly than smaller ones, Vega's main-sequence lifetime is roughly one billion years, a tenth of the Sun's. [60] The current age of this star is about 455 million years, [ 61 ] or up to about half its expected total main-sequence lifespan.
One recent estimate of the total mass of the LMC is about 1/10 that of the Milky Way. That would make the LMC rather a large galaxy in the current observable universe. Since the sizes of relatively nearby galaxies are highly skewed, the average mass can be a misleading statistic.
Although traditionally it has been suggested the evolution of a star into a red giant will render its planetary system, if present, uninhabitable, some research suggests that, during the evolution of a 1 M ☉ star along the red-giant branch, it could harbor a habitable zone for several billion years at 2 astronomical units (AU) out to around ...
Data has been accumulated from several clusters younger than one billion years (Gyr) of age and one cluster with an age of 2.5 Gyr. Another data point on the surface is from the Sun with an age of 4.56 Gyr and a rotation period of 25 days. Using these results, the ages of a large number of cool galactic field stars can be derived with 10% ...