Star on EARTH Magazine

Second stars can distort planet size estimates

Wed, 18 Oct 2017 12:11:52 -0400

An artist's illustration of a two-star system: One star can be obscured by the light of another, making it difficult to estimate the size of planets orbiting the stars. Credit: NASA/JPL-Caltech.

When light from a star is blocked by another celestial body — as when the moon obstructed light from the much-larger sun during the recent solar eclipse — astronomers can estimate the density of exoplanets that orbit the star. And from the density, they can determine whether a planet is rocky like Earth or gaseous like Jupiter. But a new study in the Astronomical Journal shows that such density assessments, which are normally calculated from the size of the planet, may be skewed by the presence of “hidden” stars.

High-powered simulation tracks evolution of universe in detail

Thu, 25 Sep 2014 14:14:32 -0400

Illustris simulation of dark matter transitioning to gas density. Credit: Illustris Simulation.

The universe burst into existence 14.6 billion years ago, and has been expanding ever since. Of course, humans have only been around to glimpse the most recent fraction of stellar history. Now, a new high-powered computer simulation called Illustris, which traces more than 13 billion years of cosmological evolution, is giving scientists and the public alike an armchair view of how things came to look the way they do.

Twinkle, twinkle new little star

Tue, 19 Aug 2014 13:43:27 -0400

A new hybrid star, called a Thorne-Zytkow object, was observed in the Small Magellanic Cloud, one of the closest and brightest galaxies near the Milky Way. Credit: NASA/CXC/JPL-Caltech/STScI.

What’s red, sparkly and far from home? Not Dorothy’s shoes, but a Thorne-Zytkow object (TZO), a type of hybrid star theorized since 1975 to exist but not observed until now.

Unprecedented low water-vapor levels detected on exoplanets

Tue, 12 Aug 2014 15:57:13 -0400

Illustration of a 'hot Jupiter' exoplanet orbiting its star. Credit: Haven Giguere, Nikku Madhusudhan.

Dust surrounding a star coalesces into larger particles, spinning and building over a million years or more to create the beginning of a planet. This is part of the widely accepted core-accretion theory of planet formation. As planetesimals combine into a planet, surrounding gases are attracted by the gravity of the new planet, forming the planet’s new atmosphere. According to the theory, oxygen, in the form of water vapor in the atmosphere, will be the most abundant element present on the planet. However, recent discoveries have raised questions about the commonly held understanding of the processes involved in planet formation.

North star loses mass but still shines bright

Wed, 25 Apr 2012 15:34:42 -0400

This sequence of images taken by the Hubble Space Telescope shows that the North Star, Polaris, is a triple star system. New research also confirms the main North Star is a Cepheid variable. NASA, ESA, N. Evans (Harvard-Smithsonian CfA), and H. Bond (STScI)

The North Star, the Pole Star, the Guiding Star, Polaris: Its many names reflect the many centuries humans have gazed northward to it for guidance. Because Earth’s North Pole is aligned with Polaris’ position in the sky, the star appears motionless, providing a steadfast beacon for early sailors and adventurers alike. But the star itself is far from motionless. In fact, Polaris is a specific type of star known as a Cepheid variable, which pulsates, varying in size and luminosity over a period of days and, according to recent observations, also ejects large amounts of mass into space. Now, combining 170 years worth of observational data on Polaris’ pulsation rates with state-of-the-art stellar evolution models, a team of scientists suggests that Polaris is losing mass at a significant rate. But this does not mean Polaris will vanish from the night sky anytime soon.

Online stargazing with GigaGalaxy Zoom

Thu, 05 Jan 2012 06:41:58 -0500

Blogging on EARTH

In need of a sense of perspective? The European Southern Observatory has a new way to look at the universe: with a zoom button.

ESO has unveiled an interactive, online 360-degree panoramic view of the night sky called GigaGalaxy Zoom, with which you can gaze at the stars as they appeared above two of the observatory's dark, crystal-clear viewing sites in Chile (La Silla and Paranal). ESO plans to release three extremely high-resolution images, each successively more detailed, for viewing at GigaGalaxy Zoom as part of the International Year of Astronomy 2009.

Scientists find watery super-Earth

Thu, 05 Jan 2012 06:41:58 -0500

Newly discovered super-Earth GJ 1214b orbits a red dwarf star 40 light-years from Earth in this artist's conception. David A. Aguilar, CfA

The search for Earth-like planets has never looked better. Scientists say they have discovered a water-rich planet that is only 2.7 times larger than Earth. Although positioned just outside the habitable zone for life, the planet gives scientists their best hope yet that other Earth-like planets exist in our universe.