We have seen how a star’s color or peak wavelength indicates its characteristic temperature near the stellar surface. But what about the temperature in the star’s deep interior? Intuitively, we expect this to be much higher than at the surface, but under what conditions does it become hot enough to allow for nuclear fusion to power the star’s luminosity? And how does it scale quantitatively with the overall stellar properties, like mass, radius, and luminosity? To answer these questions, we identify two distinct considerations.

The post-main-sequence evolution of stars with higher initial mass (>8 solar masses) has some distinct differences from those of solar and intermediate-mass stars. We show how multiple-shell burning can lead to core-collapse supernovae, which are important in generating elements heavier than iron. Some supernovae can lead to the curious stellar end points of neutron stars and black holes.

Exoplanets are planets orbiting stars other than our sun. While some have now been detected (or confirmed) by direct imaging, most exoplanet detections have been made via two other more indirect techniques, known as the radial velocity and transit methods. These methods have analogs in the study of stellar binary systems, as outlined in Chapter 10. We explore the population of known exoplanets and how we must compensate for observational biases inherent in each of these techniques.

We start with some of the historical work on measuring distances to galaxies, leading to the Hubble (or Hubble-Lemaitre) law, a linear proportionality between recession velocity and and a galaxy’s distance, with a proportionality constant known as the Hubble constant. For more distant galaxies, it becomes increasingly difficult to detect and resolve even giant stars like Cepheid variables as individual objects, limiting their utility in testing the Hubble law to larger distances and redshifts. For much larger distances, an important alternative method is the Tully–Fisher relation.

To test which of these models applies to our universe, one needs to extend redshift measurements to large distances, out to several Giga-light years. The most successful approach has been to use white dwarf supernovae (SN type Ia) as very luminous standard candles. One of the greatest surprises of modern astronomy is that the expansion of the universe must be accelerating! This implies there must be a positive, repulsive force that pushes galaxies apart, in opposition to gravity. We dub this force "dark energy."

Earth’s moon is quite distinct from other moons in the solar system, in being a comparable size to Earth. We explore the theory that a giant impact in the chaotic early solar system led to the Moon’s formation, and bombardment by ice-laden asteroids provided the abundant water we find on our planet. Further we find that Earth’s magnetic field shields us from solar wind protons, that protect our atmosphere from being stripped away. The icy moons of Jupiter and Saturn are the best targets for exploring if life exists elsewhere in the solar system.

This chapter characterizes the burden of suicidal behavior among adolescents using a sociological lens and a public health prevention approach. It describes the public health approach to preventing adolescent suicidal behavior. The public health approach includes assessing the problem; identifying causes or risk and protective factors; developing and evaluating programs; and implementing and disseminating findings. The chapter gives numbers on the extent of the problem among adolescents, describing the numbers, rates, and trends of fatal and nonfatal suicidal behavior among youth, then a summary of what is known about the community- and societal-level risk, and protective factors of the problem are presented, showing where sociology and public health complement each other. Lastly, the authors list several community- and societal-level prevention programs and the implications for what can be done to prevent adolescent suicidal behavior. Which types of suicidal behavior identified by Durkheim (i.e., anomic, egoistic, fatalistic, and altruistic) are addressed by modern prevention programs?

The close proximity of the Sun, and its extreme apparent brightness, makes it by far the most important star for lives here on Earth. In modern times we have access to powerful telescopes, both on the ground and in space, that observe and monitor the Sun over a wide range of wavelength bands. These vividly demonstrate that the Sun is in fact highly structured and variable over a wide range of spatial and temporal scales.

As a basis for interpreting observations of binary systems in terms of the orbital velocity of the component stars, we review the astrometric and spectrometric techniques used to measure the motion of stars through space. Nearby stars generally exhibit some systematic motion relative to the Sun, generally with components both transverse (i.e., perpendicular) to and along (parallel to) the observed line of sight.

What is the relationship between gender and mental health? What social forces shape this relationship? Evidence reveals that there are no differences by gender in overall rates of psychopathology, but gender predicts the types of psychopathology diagnosed and reported. Women suffer from higher rates of depression and anxiety (referred to as internalizing disorders), and men have higher rates of substance abuse and antisocial disorders (referred to as externalizing disorders). Sarah Rosenfield, Dena T. Smith, and Maleah Fekete concentrate on dominant gender conceptions – those held by groups in positions of power, which in the United States are primarily White and affluent. Focusing on the US adult population, the authors describe differences between men and women in power, responsibilities (i.e., different role positions), and personal characteristics that are relevant for mental health. For example, women earn less money, have jobs with less power and autonomy, and experience an overload of job and family demands more often than men. They have closer social ties, which bring more support but also more negative interactions. Women have personal characteristics of lower self-esteem and mastery than men. They are more nurturant and emotionally engaged, compared to men’s greater independence and assertiveness. Finally, gender predicts self-salience, that is, beliefs about the importance of the self versus others in social relations: women put others’ interests first more often, which promotes internalizing problems, while men tend to privilege the self more strongly, facilitating externalizing problems. It is important to note that most research on gender and mental health compares men and women while ignoring minority gender identities. It is also important to consider gender’s intersection with other social determinants of mental health such as socioeconomic status (SES), race, and ethnicity. The authors suggest that socializing practices encouraging high self-regard along with high regard for others improve mental health. What role can colleges play in encouraging high self-regard and regard for others for all students?

Our initial introduction of surface brightness characterized it as a flux confined within an observed solid angle. But actually the surface brightness is directly related to a more general and fundamental quantity known as the "specific intensity." The light we see from a star is the result of competition between thermal emission and absorption by material within the star.

The concept of accessed status lies at the intersection of two classic research traditions: stratification and social networks. Status is one of the most fundamental concepts that stratification sociologists contribute to social science and public discourse. From the social network perspective, status can be dichotomized into personal status (one’s own ranked positions) and accessed status (the ranked positions of one’s network members). In comparison to personal status, accessed status has been given much less attention (partly due to the lack of network data). Its theoretical meaning and role for well-being, mental well-being in particular, is actually relatively more complicated and intriguing, and appears to be puzzlingly double-edged (helpful and harmful). This chapter focuses on the relationship between accessed status and mental well-being. It first introduces accessed status and the external–internal well-being continuum and subsumes mental well-being within this continuum. It then describes a pair of competing theories (social capital versus social cost) on the double-edged role of accessed status and summarizes theoretical extensions and empirical efforts analyzing the diverse effects (direct, indirect, mediating, and interaction) of accessed status on mental well-being. It concludes with a discussion of future research directions and calls for more future efforts in the analysis of accessed status and well-being as well as network data collection. How is accessed status defined and measured? Where does mental well-being fall on the external–internal well-being continuum? Why does accessed status exhibit a more complex (both protective and harmful) association with mental well-being than with other types of well-being?