Characterizing the satellites of massive galaxies up to z ∼ 2: young populations to build the outskirts of nearby massive galaxies

The accretion of minor satellites is currently proposed as the most likely mechanism to explain the significant size evolution of the massive galaxies during the last ∼10 Gyr. In this paper, we investigate the rest-frame colours and the average stellar ages of satellites found around massive galaxies (M_star ∼ 10^11 M_⊙) since z ∼ 2. We find that the satellites have bluer colours than their central galaxies. When exploring the stellar ages of the galaxies, we find that the satellites have similar ages to the massive galaxies that host them at high redshifts, while at lower redshifts they are, on average, ≳1.5 Gyr younger. If our satellite galaxies create the envelope of nearby massive galaxies, our results would be compatible with the idea that the outskirts of those galaxies are slightly younger, metal-poorer and with lower [α/Fe] abundance ratios than their inner regions.

Identification of geostationary satellites using polarization data from unresolved images

In order to protect critical military and commercial space assets, the United States Space Surveillance Network must have the ability to positively identify and characterize all space objects. Unfortunately, positive identification and characterization of space objects is a manual and labor intensive process today since even large telescopes cannot provide resolved images of most space objects. Since resolved images of geosynchronous satellites are not technically feasible with current technology, another method of distinguishing space objects was explored that exploits the polarization signature from unresolved images. The objective of this study was to collect and analyze visible-spectrum polarization data from unresolved images of geosynchronous satellites taken over various solar phase angles. Different collection geometries were used to evaluate the polarization contribution of solar arrays, thermal control materials, antennas, and the satellite bus as the solar phase angle changed. Since materials on space objects age due to the space environment, it was postulated that their polarization signature may change enough to allow discrimination of identical satellites launched at different times. The instrumentation used in this experiment was a United States Air Force Academy (USAFA) Department of Physics system that consists of a 20-inch Ritchey-Chrétien telescope and a dual focal plane optical train fed with a polarizing beam splitter. A rigorous calibration of the system was performed that included corrections for pixel bias, dark current, and response. Additionally, the two channel polarimeter was calibrated by experimentally determining the Mueller matrix for the system and relating image intensity at the two cameras to Stokes parameters S0 and S1. After the system calibration, polarization data was collected during three nights on eight geosynchronous satellites built by various manufacturers and launched several years apart. Three pairs of the eight satellites were identical buses to determine if identical buses could be correctly differentiated. When Stokes parameters were plotted against time and solar phase angle, the data indicates that there were distinguishing features in S0 (total intensity) and S1 (linear polarization) that may lead to positive identification or classification of each satellite.

Etude sur le système solaire; nouvelle loi des distances des planètes et des satellites,

Mode of access: Internet.

Tables écliptiques des satellites de Jupiter : d'apres la théorie de M. le Marquis de Laplace, et la totalité des observations faites depuis 1662 jusqu'à l'an 1802 /

Mode of access: Internet.

Astronomy of the satellites of the Earth, Jupiter and Saturn : grounded upon Sir Isaac Newton's theory of the Earth's satellite ... Also new tables of the motions of the satellites of Jupiter and Saturn ... by which their places and position ... may be exactly determined at any given time. Adapted to the meridian of London. To which is added a problem to find the latitude of the place by the altitude of the sun, moon, or star, upon any azimuth ... /

Mode of access: Internet.

Tables astronomiques du Soleil, de la Lune, des planetes, des etoiles fixes et des satellites de Jupiter et de Saturne ... /

Mode of access: Internet.

Direct broadcast satellites : policies, prospects, and potential competition /

Item 126-D-3

Popular astronomy : A concise elementary treatise on the sun, planets, satellites and comets /

Mode of access: Internet.

Tables écliptiques des satellites de Jupiter : d'après la théorie de leurs attractions mutuelles et les constantes déduites des observations /

Mode of access: Internet.

Naval Satellite Operations Center : Navy satellites for sea control.

Shipping list no.: 90-406-P.

Communications satellites : challenges of the future.

Mode of access: Internet.

Facilitating Locking Pin Alignment in Transtibial Amputees via Auto-Retracting Tethered Pin

Thesis (Master's)--University of Washington, 2016-06