With 500 Startups Accelerator’s new class introduction videoand its notorious chant, you can’t help but wonder if the current system for funding startups is really the best route to building lasting companies. Some even believe that…
Unfortunately, stars don’t have birth certificates. So, astronomers have a tough time figuring out their ages. Knowing a star’s age is critical for understanding how our Milky Way galaxy built itself up over billions of years from smaller galaxies. But Jason Kalirai of the Space Telescope Science Institute and The Johns Hopkins University’s Center for Astrophysical Sciences, both in Baltimore, Md., has found the next best thing to a star’s birth certificate.
Using a new technique, Kalirai probed the burned-out relics of Sun-like stars, called white dwarfs, in the inner region of our Milky Way galaxy’s halo. The halo is a spherical cloud of stars surrounding our galaxy’s disk. Those stars, his study reveals, are 11.5 billion years old, younger than the first generation of Milky Way stars. They formed more than 2 billion years after the birth of the universe 13.7 billion years ago. Previous age estimates, based on analyzing normal stars in the inner halo, ranged from 10 billion to 14 billion years. Kalirai’s study reinforces the emerging view that our galaxy’s halo is composed of a layer-cake structure that formed in stages over billions of years.
White dwarf stars have remarkable properties, yet they are very simple. These stripped cores of normal hydrogen-burning stars are about 1 million times denser than matter on Earth. This means that a tablespoon of material from a white dwarf’s surface would weigh as much as a school bus on Earth. White dwarfs also have no fuel to generate energy, and most of their atmospheres contain a single atom, hydrogen.
The second figure illustrates the spectral features of a white dwarf, in comparison to the Sun and a blue giant. The white dwarf spectrum is simple, containing only absorption lines from the hydrogen atom. But, unlike the same lines in the blue giant spectrum (a bloated star with a low density), the features in the white dwarf are broadened due to the intense pressure on the surface of the star (essentially, the energy levels of the atom are being perturbed). This broadening of the lines, as well as their depth, is directly related to the mass and temperature of the star. Unlike for most stars, astronomers can therefore reliably establish fundamental properties for white dwarfs from their spectra.
© - kunstoph - STOPH SAUTER - 2013
The mad killing of 20 first-graders and six of their teachers in Newtown, Conn., followed by the mayhem of the Boston Marathon bombs, has ignited passionate discussion about gun violence in the U.S.
Misery and death inflicted on the innocent, and especially children, are devastating. But the furor over these mass assaults by individuals — terrible, but rare — obscures the routine violence of a country spreading poverty at home and war abroad. And the mainstream debate doesn’t even touch upon the need and right of working and oppressed people to effectively defend themselves against an inhumane social order that is utterly dependent on armed force to survive.
For anyone concerned about reducing violence, these are very real issues.
Poverty kills. Of all the U.S. deaths in 2000, 36 percent were caused by social diseases such as racist segregation, income inequality, inadequate social services, minimal education, and poverty. So concluded an impressive Columbia University study reported in the American Journal of Public Health in 2011.
By comparison, just over 1 percent of U.S. deaths in 2010 were gun deaths. And three out of five of these were suicides, not homicides.
It’s clear that, first, these statistics hardly support tightening gun laws and, second, poverty and inequality are far more fatal than guns.
Joblessness, dangerous jobs, stingy or nonexistent healthcare, environmental ills, and systemic sexism and racism are taking a profound toll. Their cause is the capitalist economy, owned and run by a very few individuals of obscene wealth and power.
Integral to this economy is the weapons industry, with its arms lobbyists including the NRA. Now this industry’s profits are bolstered by the permanent “war on terror,” which has intensified the U.S. culture of militarism and provides justification for foreign wars and for repression, spying, and torture abroad and at home. They call it “national security,” but the intent is to keep rebellion at bay.
We talked with Kalpona Akter, the executive director of the Bangladesh Center for Worker Solidarity, about how American consumers can best pressure US corporations to protect workers abroad. Read the full interview here.