A continuous flaring- to normal-branch transition in Scorpius X-1
INAF – Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate (LC), Italy e-mail: email@example.com
2 INAF – Osservatorio Astronomico di Roma, via di Frascati 33, 00040 Monte Porzio Catone (Roma), Italy
Accepted: 8 June 2005
We report the first resolved rapid transition from a Flaring Branch Oscillation to a Normal Branch Oscillation in the RXTE data of the Z source Sco X-1. The transition took place on a time scale of ~100 s and was clearly associated to the Normal Branch-Flaring Branch vertex in the color–color diagram. We discuss the results in the context of possible association of the Normal Branch Oscillation with other oscillations known both in Neutron-Star and Black-Hole systems, concentrating on the similarities with the narrow 4–6 Hz oscillations observed at high flux in Black-Hole Candidates.
Key words: accretion, accretion disks / X-rays: binaries / stars: individual: Sco X-1
© ESO, 2006