How many stars universe
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Estimating the Total Number of Stars in the Universe
Photometry-Based Estimation of Stars
A recent study has provided a novel estimation of the total number of stars in the Universe using photometry-based methods. This approach relies on the energy conservation law and actual measurements of extragalactic background light levels. By assuming that every radiated photon remains within the Universe, the study approximates the Universe as an integrating cavity without losses. This method has led to an estimation of approximately 6×10²² stars in the Universe1.
Historical and Observational Data on Stars
Historically, the number of stars visible to the naked eye on a clear night is roughly 5,000, a figure that has often been used symbolically to represent infinity. However, modern astronomical techniques have vastly expanded our understanding. For instance, a comprehensive catalogue of mean UBV data on stars includes data on the magnitudes of more than 100,000 stars in our galaxy alone2 3.
Variable Stars and Their Distribution
The Optical Gravitational Lensing Experiment (OGLE) has identified nearly 66,000 Mira-type variable stars in the Milky Way. This extensive collection, which includes stars located in both the Galactic bulge and disk, provides valuable data for studying the three-dimensional structure of our galaxy4.
High-Mass Stars and Multiplicity
A spectroscopic survey focusing on the multiplicity of high-mass stars reveals that a significant majority of stars with masses above 16 solar masses form close binary systems. This high frequency of binary systems among O-type stars suggests that multiplicity is likely a result of the star formation process rather than tidal capture in dense clusters5.
Stellar Systems and the Scale of the Universe
The diameter of the observable Universe, as made accessible by advanced telescopes, is about 600 million light-years. Within this vast expanse, there are approximately 100 million stellar systems, each containing an average of 10¹⁰ stars. Despite the immense number of stars, they occupy only a minuscule fraction of space, with the vast majority of the Universe being empty6.
Formation of the First Stars
The formation of the first stars in the Universe is a complex process involving the cooling of primordial gas and the formation of dense molecular clouds. Simulations suggest that these early stars were massive, with the formation of a single star per pregalactic halo being the norm due to radiative feedback inhibiting further star formation8.
Conclusion
In summary, the total number of stars in the Universe is estimated to be around 6×10²², based on photometry-based methods. This vast number is supported by various observational data and catalogues, which provide detailed information on the distribution and characteristics of stars within our galaxy and beyond. The formation and multiplicity of stars, especially high-mass stars, further enrich our understanding of the stellar population in the Universe.
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Most relevant research papers on this topic
Photometry-based estimation of the total number of stars in the Universe.
The total number of stars in the Universe is about 61022, based on energy conservation law and extragalactic background light levels.
The OGLE Collection of Variable Stars: Nearly 66,000 Mira Stars in the Milky Way
The OGLE database contains 65,981 Mira-type variable stars, with most new discoveries, and can be used as a training set for machine-learning classification algorithms.
A spectroscopic survey on the multiplicity of high-mass stars
High-mass stars form close binary systems, with a majority (>82%) forming close pairs with similar mass, supporting a multiplicity originating from formation rather than tidal capture in dense clusters.
Highly CitedEmpty Space
Extragalactic space is believed to be empty, but in interstellar space, electrons, protons, atoms, gas molecules, and larger matter exist.
Highly CitedCatalogue of Ap, HgMn and Am stars
This paper presents a revised catalog of 8205 Ap, HgMn, and Am stars, including revised identifications, additional stars, and revised information from literature.
Highly CitedThe Formation of the First Star in the Universe
At most one massive metal-free star forms per pregalactic halo, with radiation feedback inhibiting star growth and preventing further star formation in the same pregalactic object.
Highly CitedThe star-formation history of the Universe from the stellar populations of nearby galaxies
The peak of star formation was more recent, around five billion years ago, and high-mass galaxies have different histories from low-mass galaxies.
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