Related Experiment Video
Updated: Aug 4, 2026
07:04
High Precision Zinc Isotopic Measurements Applied to Mouse Organs
Published on: May 22, 2015
Neutron-Capture Element Abundances in the Globular Cluster M15
The Astrophysical Journal
|June 20, 2000
Summary
This study analyzed red giant stars in M15, finding their neutron-capture element abundances match the solar system r-process distribution. This implies the age of neutron-capture material in M15 stars is 14+/-3 billion years.
Area of Science:
- Astronomy
- Astrophysics
- Stellar Evolution
Background:
- Globular clusters like M15 provide insights into early galactic chemical evolution.
- Neutron-capture elements are crucial for understanding nucleosynthesis and stellar ages.
Purpose of the Study:
- To determine the abundances of neutron-capture elements in red giant stars within the M15 globular cluster.
- To use the radioactive element thorium as a chronometer to estimate the age of the neutron-capture material.
Main Methods:
- Obtained high-resolution, blue-violet spectra of three red giant branch tip stars in M15 using the Keck I High-Resolution Echelle Spectrograph.
- Analyzed spectral data to determine abundances of heavy elements (Z>=56), including thorium (Th) and europium (Eu).
Main Results:
- The observed abundances of heavy elements in the studied stars align with a scaled solar system r-process (rapid neutron-capture process) distribution.
- A weighted mean Th/Eu ratio suggests an age of 14+/-3 billion years for the neutron-capture material in M15 stars.
Conclusions:
- The findings support the hypothesis of a common r-process source for heavy elements in M15.
- The derived age is consistent with other recent age estimates for Galactic globular clusters, aiding in understanding the Milky Way's formation timeline.
More Related Videos
Related Concept Videos
03:26Electron Configuration of Multielectron Atoms
The alkali metal sodium (atomic number 11) has one more electron than the neon atom. This electron must go into the lowest-energy subshell available, the 3s orbital, giving a 1s22s22p63s1 configuration. The electrons occupying the outermost shell orbital(s) (highest value of n) are called valence electrons, and those occupying the inner shell orbitals are called core electrons. Since the core electron shells correspond to noble gas electron configurations, we can abbreviate electron...
03:08Atomic Radii and Effective Nuclear Charge
The elements in groups of the periodic table exhibit similar chemical behavior. This similarity occurs because the members of a group have the same number and distribution of electrons in their valence shells.
03:18Nuclear Stability
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively charged protons together in the...
To hold positively charged protons together in the...
03:20Nuclear Transmutation
Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with another particle. The first manmade nucleus was produced in Ernest Rutherford’s laboratory in 1919 by a transmutation reaction, the bombardment of one type of nuclei with other nuclei or with neutrons. Rutherford bombarded nitrogen-14 atoms with high-speed α particles from a natural radioactive isotope of radium and observed protons being...
00:59Atomic Nuclei: Nuclear Magnetic Moment
All atomic nuclei are positively charged. When they have a nonzero spin, they behave like rotating charges. As a consequence of their charge and spin, these nuclei generate a magnetic field (B). This, in turn, gives rise to a magnetic moment (μ), which is randomly oriented in the absence of an external magnetic field. When an external magnetic field (B0) is applied, the magnetic moment vectors can align with the field or against it in 2 + 1 orientations. A hydrogen nucleus, which is just a...
01:16Other Nuclides: 31P, 19F, 15N NMR
Many organic, inorganic, and biological molecules contain spin-half nuclei such as nitrogen-15, fluorine-19, and phosphorus-31. As a result, NMR studies of these nuclei have found extensive applications in chemical and biological research.
While fluorine-19 and phosphorous-31 have high natural abundances (100%) and positive gyromagnetic ratios, nitrogen-15 has a low natural abundance and a negative gyromagnetic ratio. However, nitrogen-15 is still preferred over nitrogen-14 (which has a high...
While fluorine-19 and phosphorous-31 have high natural abundances (100%) and positive gyromagnetic ratios, nitrogen-15 has a low natural abundance and a negative gyromagnetic ratio. However, nitrogen-15 is still preferred over nitrogen-14 (which has a high...