H-R Diagram
The two primary variables plotted on the axes of a Hertzsprung-Russell (H-R) diagram.
What are Surface Temperature and Luminosity?
This measurement compares the brightness or energy output of a star relative to the Sun.
What is Luminosity?
Compared to low-mass stars, high-mass stars have this type of lifespan due to their rapid fusion rates.
Compared to low-mass stars, high-mass stars have this type of lifespan due to their rapid fusion rates.
The primary nuclear process powering Main Sequence stars by combining light atomic nuclei into heavier ones.
What is Nuclear Fusion?
Einstein's famous equation demonstrating how mass lost during nuclear fusion converts directly into energy.
What is $E = mc^2$?
This prominent band running from top-left to bottom-right contains stars that spend about 90% of their lives fusing hydrogen into helium.
What is the Main Sequence?
This standard unit ($M_\odot$), equal to approximately $2 \times 10^{30}\text{ kg}$, is used to measure and compare the mass of stars.
What is a Solar Mass?
This contracting cloud of gas and dust increases its spin and density before becoming a full-fledged star.
What is a nebula?
The element produced when three helium nuclei fuse together inside an evolving star's core.
What is Carbon?
The primary fuel element consumed in the core of stars during their Main Sequence phase.
What is Hydrogen?
Surface temperature on an H-R diagram changes in this specific direction across the horizontal axis.
What is decreasing from left to right?
On the Main Sequence, larger and more massive stars consistently exhibit higher values for these two physical properties.
What are Surface Temperature and Luminosity?
In general, stars spend the vast majority of their lives in this stable phase where they fuse hydrogen into helium in their cores.
What is the Main Sequence stage?
The heaviest element that can be created in the core of a massive star via stellar fusion before core collapse.
What is Iron ($\text{Fe}$)?
The process of heavy atomic nuclei splitting into lighter ones—which is not the process that powers stars.
What is Nuclear Fission?
A star with a surface temperature of $28,000\text{ K}$ and a luminosity of $10,000$ solar units would be located in this region of an H-R diagram.
What is the upper portion of the Main Sequence?
Astronomers analyze these distinct dark or bright spectral patterns in a star's light to determine its surface temperature and chemical composition.
What are Absorption and Emission Spectra?
The stage a massive Main Sequence star transitions into after exhausting its core hydrogen, expanding greatly before core collapse.
What is a Red Supergiant?
Elements heavier than iron (such as Gold or Uranium) are synthesized exclusively during this violent event.
What is a Supernova explosion?
The explosive event that scatters heavy elements across space to seed future star systems and planets.
The explosive event that scatters heavy elements across space to seed future star systems and planets.
Stars located in the upper-right region of an H-R diagram have low surface temperatures but extremely high brightness due to this physical property.
What is a large size (or radius)?
The fundamental stellar property that dictates both a star's rate of nuclear fusion and its overall lifespan.
What is Initial Mass?
The dense remnant core left behind by a low-to-medium mass star like our Sun after shedding its outer layers.
What is a White Dwarf?
The overarching scientific term for the creation of new chemical elements inside stars through nuclear fusion.
What is Stellar Nucleosynthesis?
Main Sequence stars generate massive amounts of energy through fusion with near $100\%$ energy efficiency compared to chemical reactions because they overcome this force pushing protons apart.
What is Electrostatic (or Electromagnetic) Repulsion?