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Daily Archives: July 24, 2009

Using Kepler to Detect Exomoons

In a paper submitted to the Monthly Notices of the Royal Academy of Sciences, available online now here, astronomers use simulated data, expected from the Kepler mission photometer, to demonstrate how the Kepler-class photometry data can be used to detect moons around large exoplanets (exomoons). They conclude that “that habitable-zone exomoons down to 0.2″ solar masses, “may be detected and ~25, 000 stars could be surveyed for habitable-zone exomoons within Kepler ’s field-of view.”

Fermi’s Paradox Re-examined

In a paper published in the Serbian Astronomical Journal, available online now here, astronomers re-examine the widely known Fermi Paradox. Fermi expressed this paradox in the early 1950s in a debate with colleagues who felt that there must be many instances of intelligent life in our galaxy (extraterrestrial life). However, the search (SETI) for extraterrestrial life has yet to find any. He ended his argument by asking simply, “so where are they.” There is an entire book about this subject, originally published in 2002. You can check it out online here. The aforementioned journal article has a European flavor to it, and gives more of a history to the question in general.

Quiest Sun May Be Cover For Activity Beneath the Surface

In a paper to be published in the Astrophysical Journal Letters, available online now here, a team of British astronomers address the concerns some have stated over the recent quiet Sun. Apparently, using the techniques of helioseismology, which like its namesake seismology, uses surface waves to determine what is happening beneath the surface, astronomers have discovered that there is evidence of quite a bit of activity just beneath the surface of the Sun or photosphere. Apparently there is “activity-related
processes occurring in the solar interior, which are yet to reach the surface.”

Public to Gain Access to CoRoT Data

In a paper to be published in Astronomy and Astrophysics, available online now here, NASA and its European collaborators at LAEX (Laboratorio de Astrof´?sica Estelar y Exoplanetas) have announced the public accessibility of data from the CoRoT mission. These data “archives are designed with the aim of delivering science-quality data in a simple and ecient way.” They can be accessed at at http://sdc.lae .inta.es/corotfa/ and http://nsted.ipac.caltech.edu.

Brown Dwarfs and their Formation

In a paper to be published in the Astrophysical Journal Letters, available online now here, a team of Japanese astronomers report the first direct simulation of the formation of brown dwarfs in the core of a nebula. As they report, their “results indicate that brown dwarfs can be formed in compact cores in the same manner as hydrogen-burning stars, and the magnetic field and protostellar outflow are essential in determining the star formation efficiency and stellar mass.”

When White Dwarfs Collide

In a paper submitted to the Astrophysical Journal Letters, available online now here, an international team of astronomers propose a model for the development of a Type Ia supernova. In their model, a Type Ia supernova develops from the collision of two white dwarfs. This needs further examination before it makes its way into textbooks.

Wavelets Aid in Analysis of Type Ia Supernovae Spectra

Type Ia supernovae are those supernovae which develop within a binary star system, where one of the stars has already ended its life as a white dwarf, and manages to “steal” so much material from its companion star that it ends up collapsing under its own weight, and the rebound gives us a supernova explosion. These type of supernovae are especially of interest to astronomers because it was discovered that they can be used as a way to gauge the distance to remote galaxies which have this type of supernova explosion. In fact, it’s these type of supernovae which provided the initial evidence for astronomers that the universe is not only expanding, but it is accelerating in its expansion. Analysis of the spectra of Type Ia supernovae is also of interest, and now in a paper released this week, available online here, astronomers have discovered that the use of a mathematical tool called wavelets, can provide superior analysis of Type Ia supernovae spectra.

Astrophysicists Offer Explanation for Maunder Minimum

If you check Wikipedia for a definition of the Maunder Minimum, you will find that it is “the name given to the period roughly spanning 1645 to 1715 by John A. Eddy in a landmark 1976 paper published in Science titled “The Maunder Minimum”, when sunspots became exceedingly rare, as noted by solar observers of the time.” Jack Eddy died this past June. Our paths crossed as we were both associated with a Michigan consortium called CIESIN. Anyhow, in a paper to appear in Research in Astronomy & Astrophysics, physicists offer an explanation of why this sunspot minimum occurred. You can read about their explanation online now here.

Astronomers Seek Nature of Exoplanet Not Much Larger than Earth

In a paper to appear in Astronomy and Astrophysics, available online now here, astronomers speculate on the nature of one of the most recently discovered exoplanets, known as CoRoT-7b. This exoplanet is estimated to be at least 1.68 times the radius of the Earth. However, it is so close to its star that it takes less than a day for it to complete a single orbit. With better refinements of CoRoT-7b’s mass, and spectral analysis, astronomers hope to understand the nature and composition of the exoplanet. They present one possible view, which can be confirmed with additional observations.

Quasars and Galaxy Formation

The hallmark of a good theory is its testability. In a paper to appear in Astronomy and Astrophysics, available online now here, an international team of astronomers have laid out what they refer to as a ‘new paradigm’ for the evolution of galaxies and the role played by active galactic nuclei (AGN). They conclude that “quasars play a key role in the formation of galaxies.” Furthermore, they offer observational tests that would confirm or deny their galaxy formation theory. Next week in my summer astronomy course I will be discussing the nature of active galaxies and the formation of galaxies in the early universe.

July 2009
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