Volume 397, Number 1, January I 2003
|Page(s)||147 - 157|
|Section||Galactic structure, stellar clusters, and populations|
|Published online||11 December 2002|
The stellar activity-rotation relationship revisited: Dependence of saturated and non-saturated X-ray emission regimes on stellar mass for late-type dwarfs *
INAF - Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
2 INAF - Osservatorio Astronomico di Roma, Via Frascati 33, 00040 Monteporzio, Italy
Corresponding author: N. Pizzolato, firstname.lastname@example.org
Accepted: 1 October 2002
We present the results of a new study on the relationship between coronal X-ray emission and stellar rotation in late-type main-sequence stars. We have selected a sample of 259 dwarfs in the range 0.5–2.0, including 110 field stars and 149 members of the Pleiades, Hyades, α Persei, IC 2602 and IC 2391 open clusters. All the stars have been observed with ROSAT, and most of them have photometrically-measured rotation periods available. Our results confirm that two emission regimes exist, one in which the rotation period is a good predictor of the total X-ray luminosity, and the other in which a constant saturated X-ray to bolometric luminosity ratio is attained; we present a quantitative estimate of the critical rotation periods below which stars of different masses (or spectral types) enter the saturated regime. In this work we have also empirically derived a characteristic time scale, , which we have used to investigate the relationship between the X-ray emission level and an X-ray-based Rossby number : we show that our empirical time scale resembles the theoretical convective turnover time for , but it also has the same functional dependence on as in the color range . Our results imply that – for non-saturated coronae – the Lx – Prot relation is equivalent to the vs. Re relation.
Key words: stars: activity / stars: late-type / X-rays: stars
© ESO, 2003
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.