Milky way galaxy stars number
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Number of Stars in the Milky Way Galaxy
Overview of Star Population in the Milky Way
The Milky Way galaxy is a vast and complex system, home to a diverse array of stars. Recent studies have provided detailed insights into the number and types of stars within our galaxy, utilizing advanced observational techniques and simulations.
Mira Variable Stars in the Milky Way
A significant contribution to our understanding of the Milky Way's stellar population comes from the Optical Gravitational Lensing Experiment (OGLE) project, which identified nearly 66,000 Mira-type variable stars. These stars are distributed across the Galactic bulge and disk, with 40,356 located in the bulge and 25,625 in the disk1. This extensive catalog of Mira variables is crucial for studying the three-dimensional structure of the Milky Way and offers a high-purity dataset for further astronomical research1.
Three-Dimensional Mapping of the Milky Way
Using the same dataset of Mira variable stars, researchers have constructed a detailed three-dimensional map of the Milky Way. This map reveals the spatial distribution of these stars, highlighting the presence of three barred components, including an X-shaped bulge and an axisymmetric disk. The study estimates the distance to the Galactic Center to be approximately 7.66 kpc, providing a clearer picture of the Milky Way's structure2.
First Stars and Galaxies
Simulations of the Milky Way's formation have identified the sites of the first stars and galaxies. These early stars, known as Population III stars, formed around redshift z = 25. The simulations suggest that there were approximately 23,000 potential star-forming sites per Milky Way-mass host, though this number is significantly reduced when considering feedback effects3. The remnants of these first stars are expected to be concentrated near the Galactic Center6.
Massive Star Clusters Near the Galactic Center
High-resolution infrared observations have revealed a compact cluster of approximately 100 young, massive main-sequence stars near the center of the Milky Way. This cluster includes some of the most massive stars in the galaxy and provides a local example of starburst phenomena, which are typically observed in more distant galaxies4.
Distribution of Ancient Stars
The oldest stars in the Milky Way, formed before redshift z = 5, are less centrally concentrated than younger stars. These ancient stars are often found in the halo and outer regions of the galaxy, having been accreted during the Milky Way's hierarchical assembly. This distribution pattern is a result of both in situ formation and external accretion processes5.
Ultra Metal-Poor Stars
Ultra metal-poor (UMP) stars, which are among the oldest in the Milky Way, provide valuable insights into the galaxy's early formation. These stars, identified using Gaia DR2 data, are currently within 20 kpc of the Sun and exhibit a wide variety of orbits. Some of these stars are confined to the inner halo, while others have larger apocentres, indicating later accretion from dwarf galaxies7.
Conclusion
The Milky Way galaxy hosts a vast and diverse population of stars, ranging from ancient Population III stars to young, massive clusters near the Galactic Center. Advanced observational projects like OGLE and simulations of galactic formation have significantly enhanced our understanding of the number and distribution of stars within our galaxy. These studies not only map the current stellar population but also trace the Milky Way's complex formation history.
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Most relevant research papers on this topic
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 Three-dimensional Map of the Milky Way Using 66,000 Mira Variable Stars
This study presents a detailed three-dimensional map of the Milky Way using 65,981 Mira variable stars, providing evidence for the X-shaped bulge component and the flaring disk, with a median distance accuracy of 6.6%.
Tracing the first stars and galaxies of the Milky Way
The first stars and galaxies in Milky Way-mass systems formed in isolation, with Lyman-Werner feedback reducing this number to 550 star-forming sites per host, and most merge with larger systems within 1.5 Gyrs.
An extraordinary cluster of massive stars near the centre of the Milky Way
This study reveals a compact cluster of 100 young, massive stars near the center of the Milky Way, potentially offering a weak analogue for studying the starburst phenomenon in local examples.
Highly CitedWhere are the most ancient stars in the Milky Way?
The oldest stars in the Milky Way are less centrally concentrated due to factors such as hierarchical assembly and gravitational feedback, with the majority of them not formed in situ.
Highly CitedThe earliest stars and their relics in the Milky Way
The first stars in the Milky Way formed around redshift z = 35, and by z = 10, the young galaxy had up to 3 x 10 4 dark matter haloes capable of forming stars by molecular hydrogen cooling.
Tracing the formation of the Milky Way through ultra metal-poor stars
Ultra metal-poor stars in the Milky Way halo can help trace the early formation of the galaxy, with some suggesting they belonged to the proto-Milky Way's backbone.
Gaia DR2 in 6D: searching for the fastest stars in the Galaxy
Gaia DR2 data reveals that 13 unbound stars, including two of the fastest stars (around 700 km s1), may be the tip of the iceberg of a large extragalactic population or the extreme velocity tail of stellar streams.
Highly CitedA common mass scale for satellite galaxies of the Milky Way
The Milky Way's satellite galaxies have a common mass of about 107 within their central 300 parsecs, indicating they are the most dark-matter-dominated galaxies known.
Highly CitedA substantial population of low-mass stars in luminous elliptical galaxies
Low-mass stars are abundant in elliptical galaxies, making up over 80% of the total number of stars and contributing over 60% of the total stellar mass, suggesting a steeper initial mass function in massive star-forming galaxies in the early Universe.
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