Search Publications
Streams, Substructures, and the Early History of the Milky Way
Helmi, Amina
The advent of the second data release of the Gaia mission, in combination with data from large spectroscopic surveys, is revolutionizing our understanding of the Galaxy. Thanks to these transformational data sets and the knowledge accumulated thus far, a new, more mature picture of the evolution of the early Milky Way is currently emerging. Two of…
Evidence for Initial Mass Function Variation in Massive Early-Type Galaxies
Smith, Russell J.
The initial mass function (IMF), describing the distribution of birth masses of stars, plays a pivotal role in establishing the observable properties of galaxies. This article reviews the evidence for variation in the IMF of massive early-type galaxies (ETGs), especially from spectroscopic studies and from dynamical and gravitational lensing measu…
Star Clusters Across Cosmic Time
Bland-Hawthorn, Joss; Krumholz, Mark R.; McKee, Christopher F.
Star clusters stand at the intersection of much of modern astrophysics: the ISM, gravitational dynamics, stellar evolution, and cosmology. Here, we review observations and theoretical models for the formation, evolution, and eventual disruption of star clusters. Current literature suggests a picture of this life cycle including the following sever…
The Faintest Dwarf Galaxies
Simon, Joshua D.
The lowest luminosity (L < 105L⊙) Milky Way satellite galaxies represent the extreme lower limit of the galaxy luminosity function. These ultra-faint dwarfs are the oldest, most dark matter-dominated, most metal-poor, and least chemically evolved stellar systems known. They therefore provide unique windows into the formati…
Exoplanetary Atmospheres: Key Insights, Challenges, and Prospects
Madhusudhan, Nikku
Exoplanetary science is on the verge of an unprecedented revolution. The thousands of exoplanets discovered over the past decade have most recently been supplemented by discoveries of potentially habitable planets around nearby low-mass stars. Currently, the field is rapidly progressing toward detailed spectroscopic observations to characterize th…
The Most Luminous Supernovae
Gal-Yam, Avishay
Over a decade ago, a group of supernova explosions with peak luminosities far exceeding (often by >100 times) those of normal events has been identified. These superluminous supernovae (SLSNe) have been a focus of intensive study. I review the accumulated observations and discuss the implications for the physics of these extreme explosions. SLS…
Accuracy and Precision of Industrial Stellar Abundances
Jofré, Paula; Heiter, Ulrike; Soubiran, Caroline
There has been an incredibly large investment in obtaining high-resolution stellar spectra for determining chemical abundances of stars. This information is crucial to answer fundamental questions in astronomy by constraining the formation and evolution scenarios of the Milky Way as well as the stars and planets residing in it. We have just entere…
Cometary Chemistry and the Origin of Icy Solar System Bodies: The View After Rosetta
Altwegg, Kathrin; Balsiger, Hans; Fuselier, Stephen A.
In situ research of cometary chemistry began when measurements from the Giotto mission at Comet 1P/Halley revealed the presence of complex organics in the coma. New telescopes and space missions have provided detailed remote and in situ measurements of the composition of cometary volatiles. Recently, the Rosetta mission to Comet 67P/Churyumov-Gera…
New View of the Solar Chromosphere
De Pontieu, Bart; Carlsson, Mats; Hansteen, Viggo H.
The solar chromosphere forms a crucial, yet complex and until recently poorly understood, interface between the solar photosphere and the heliosphere. Advances in high-resolution instrumentation, adaptive optics, image reconstruction techniques, and space-based observatories allow unprecedented high-resolution views of the finely structured and hi…
Interstellar Hydrides
Neufeld, David A.; Gerin, Maryvonne; Goicoechea, Javier R.
Interstellar hydrides—that is, molecules containing a single heavy element atom with one or more hydrogen atoms—were among the first molecules detected outside the solar system. They lie at the root of interstellar chemistry, being among the first species to form in initially atomic gas, along with molecular hydrogen and its associated ions. Becau…