Solar-cycle irradiance variations over the last four billion years

Global solar wind variations over the last four centuries

The most recent "grand minimum" of solar activity, the Maunder minimum (MM, 1650-1710), is of great interest both for understanding the solar dynamo and providing insight into possible future heliospheric conditions. Here, we use nearly 30 years of output from a data-constrained magnetohydrodynamic model of the solar corona to calibrate heliospheric reconstructions based solely on sunspot obser...

Morphological evolution of galaxies over the last 8 billion years

In this chapter I describe the motivation behind this Thesis work. I briefly review the main theoretical aspects and the very broad observational scenario, explaining the fundamental goals of this work and summarizing its most relevant contributions to the study of galaxy evolution. The review of previous work, both observational and theoretical, is by no means to be intended as exhaustive nor ...

The First Four Billion Years

Conservation of protein structure over four billion years.

Little is known about the evolution of protein structures and the degree of protein structure conservation over planetary time scales. Here, we report the X-ray crystal structures of seven laboratory resurrections of Precambrian thioredoxins dating up to approximately four billion years ago. Despite considerable sequence differences compared with extant enzymes, the ancestral proteins display t...

The heliospheric Hale cycle over the last 300 years and its implications for a “lost” late 18th century solar cycle

A Hale cycle, one complete magnetic cycle of the Sun, spans two complete Schwabe cycles (also referred to as sunspot and, more generally, solar cycles). The approximately 22-year Hale cycle is seen in magnetic polarities of both sunspots and polar fields, as well as in the intensity of galactic cosmic rays reaching Earth, with oddand even-numbered solar cycles displaying qualitatively different...