What change slowly occurs during the main-sequence lifetime of a star?
A) As hydrogen is used up in the core, the fusion rate decreases and reduces the luminosity.
B) It gathers more gas from interstellar space, increasing its mass and hence the luminosity.
C) Its core temperature slowly increases, increasing the fusion rate and hence the luminosity.
D) As the solar wind blows material into space, the decreasing mass reduces pressure in the core, which in turn reduces the fusion rate and the luminosity.
Question 2
The Doppler technique can be used to estimate the semimajor axis of a planet's orbit by
A) measuring the time it takes for the star's line-of-sight velocity to cycle from peak to peak, and using Newton's version of Kepler's Third law.
B) measuring the speed at which the star orbits the mutual center-of-mass of the star and planet, and using Newton's theory of gravity.
C) measuring the asymmetries in the velocity curve.
D) measuring the amount by which the starlight is reduced when the planet transits.
Hydrogen sulfide as an energy source for chemoautotrophic bacteria in the deep sea.
Pap smear. Cells of the cervix (shown in the center) change in appearance as they progress through
Main Facial Bones
Cumulative change for six personality-trait domains across the life course show distinct patterns.
Fossil fuel emissions and climate change
The enthalpy change for converting 10.0 g of ice at -25.0 C to water at 80.0 C is ________ kJ. ...