The Kuiper Belt is a vast disk of icy debris left over from our Sun's formation 4.6 billion years ago. Kuiper Belt objects (KBOs) are a unique class of solar-system body that has never been visited by interplanetary spacecraft. They contain well-preserved clues to the origin of our solar system. NASA's New Horizons probe will fly by Pluto in mid-2015 and then continue across the Kuiper Belt on its way toward interstellar space. The Hubble Space Telescope was used to do a deep sky survey to identify KBOs that the New Horizons spacecraft could potentially visit on its outbound trajectory. The deep sky survey was successful, and Hubble found targetable KBOs for New Horizons.
Astrophysics: How tiny galaxies form stars
Nature 514, 7522 (2014). doi:10.1038/514310a
Authors: Bruce Elmegreen
Observations of two faint galaxies with a low abundance of elements heavier than helium show that the galaxies have an efficiency of star formation less than one-tenth of that of the Milky Way and similar galaxies. See Letter p.335
Inefficient star formation in extremely metal poor galaxies
Nature 514, 7522 (2014). doi:10.1038/nature13820
Authors: Yong Shi, Lee Armus, George Helou, Sabrina Stierwalt, Yu Gao, Junzhi Wang, Zhi-Yu Zhang & Qiusheng Gu
The first galaxies contain stars born out of gas with few or no ‘metals’ (that is, elements heavier than helium). The lack of metals is expected to inhibit efficient gas cooling and star formation, but this effect has yet to be observed in galaxies with an oxygen abundance (relative to hydrogen) below a tenth of that of the Sun. Extremely metal poor nearby galaxies may be our best local laboratories for studying in detail the conditions that prevailed in low metallicity galaxies at early epochs. Carbon monoxide emission is unreliable as a tracer of gas at low metallicities, and while dust has been used to trace gas in low-metallicity galaxies, low spatial resolution in the far-infrared has typically led to large uncertainties. Here we report spatially resolved infrared observations of two galaxies with oxygen abundances below ten per cent of the solar value, and show that stars formed very inefficiently in seven star-forming clumps in these galaxies. The efficiencies are less than a tenth of those found in normal, metal rich galaxies today, suggesting that star formation may have been very inefficient in the early Universe.
Dust to dust
Nature 514, 7522 (2014). doi:10.1038/514273b
What lessons can be learned from the presentation of the gravitational-waves story?
Credit: ESA/ATG medialab; background: ESO/S. Brunier
We started this blog just over one year ago and what a year it has been! We've had the excitement of the launch, the fabulous first-light image, the challenges of some aspects of commissioning and, more recently, the relief and satisfaction of getting the 'go' for science, and even the first of Gaia's science alerts.
Now that science data have started to flow, the main activity for scientists working on the mission is preparing for the first catalogue release, planned for summer 2016. So while they are busy with that important task, we will take a break on the blog.
But don't worry, this doesn't mean that there will be no news or updates about the Gaia mission. You will be able to keep in touch with the mission via our websites (Space Science Portal, Science & Technology, and Cosmos), and you can also follow the progress of Gaia via Twitter (@ESAGaia) and using the Gaia Mission app (for iPhones) which can be downloaded from iTunes.
Thanks to all of you for following us through this exciting first year!
The Gaia Team and Blog Editors