Understanding the Oldest White Dwarfs: Atmospheres of Cool WDs as Extreme Physics Laboratories

Uniformity of the quiet solar disk: 3130 - 46700 Å

Universality in the run-up of shock waves to the surface of a star

Universality of the Small-Scale Dynamo Mechanism

Unmasking the Supernova Impostors

Unsolved Problems about Supernovae

Unusual Dust Emission from Planetary Nebulae in the Magellanic Clouds

Unusual glitch activity in the RRAT J1819-1458: an exhausted magnetar?

Unusual Trends in Solar P-Mode Frequencies During the Current Extended Minimum

Unusually Wide Binaries: Are They Wide or Unusual?

Unveiling stellar magnetic activity using CoRoT seismic observations

Unveiling the gas kinematics at 10 AU scales in high-mass star-forming regions (Milliarcsecond structure of 6.7 GHz methanol masers)

Unveiling the main heating sources in the Cepheus A HW2 region

Unveiling the phenomenon of Double Periodic Variables

Unveiling the Structure of Pre-Transitional Disks

Updated phase coherent timing solution of the isolated neutron star RX J0720.4-3125 using recent XMM-Newton and Chandra observations

Updated stellar yields from Asymptotic Giant Branch models

Updating the Historical Sunspot Record

Upflows in funnel-like legs of coronal magnetic loops

Upflows in the central dark lane of sunspot light bridges