The Role of Radioactivities in Astrophysics

I present both a history of radioactivity in astrophysics and an introduction to the major applications of radioactive abundances to astronomy

The Rate and Spatial Distribution of Novae in M31 as Determined by a 20 Year Survey

A long-term (1995-2016) survey for novae in the nearby Andromeda galaxy (M31) was conducted as part of the Research-Based Science Education initiative. During the course of the survey 180 nights of observation were completed at Kitt Peak, Arizona. A total of 262 novae were either discovered or confirmed, 40 of which have not been previously reported. Of these, 203 novae form a spatially complete sample detected by the KPNO/WIYN 0.9 m telescope within a 20 ′ × 20 ′ field centered on the nucleus of M31. An additional 50 novae are part of a spatially complete sample detected by the KPNO 4 m telescope within a larger 36 ′ × 36 ′ field. Consistent with previous studies, it is found that the spatial distribution of novae in both surveys follows the bulge light of M31 somewhat more closely than the overall background light of the galaxy. After correcting for the limiting magnitude and the spatial and temporal coverage of the surveys, a final nova rate in M31 is found to be R = 40 − 4 + 5 yr−1, which is considerably lower than recent estimates. When normalized to the K-band luminosity of M31, this value yields a luminosity-specific nova rate, ν K = 3.3 ± 0.4 yr − 1 [ 10 10 L ⊙ , K ] − 1 . By scaling the M31 nova rate using the relative infrared luminosities of M31 and our Galaxy, a nova rate of R G = 28 − 4 + 5 yr−1 is found for the Milky Way. © 2022. The Author(s). Published by the American Astronomical Society.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

D3 Dopamine and Kappa Opioid Receptor Alterations in Human Brain of Cocaine-overdose Victims

Cocaine is thought to be addictive because chronic use leads to molecular adaptations within the mesolimbic dopamine (DA) circuitry, which affects motivated behavior and emotion. Although the reinforcing effects of cocaine are mediated primarily by blockade of DA uptake, reciprocal signaling between DA and endogenous opioids has important implications for understanding cocaine dependence. We have used in vitro autoradiography and ligand binding to map D3 DA and kappa opioid receptors in the human brains of cocaine‐overdose victims. The number of D3 binding sites was increased one‐ to threefold over the nucleus accumbens and ventromedial sectors of the caudate and putamen from cocaine‐overdose victims, as compared to age‐matched and drug‐free control subjects. D3 receptor/cyclophilin mRNA ratios in the nucleus accumbens were increased sixfold in cocaine‐overdose victims over control values, suggesting that cocaine exposure also affects the expression of D3 receptor mRNA. The number of kappa opioid receptors in the nucleus accumbens and other corticolimbic areas from cocaine fatalities was increased twofold as compared to control values. Cocaine‐overdose victims exhibiting preterminal excited delirium had a selective upregulation of kappa receptors measured also in the amygdala. Understanding the complex regulatory profiles of DA and opioid synaptic markers that occur with chronic misuse of cocaine may suggest multitarget strategies for treating cocaine dependence