Search Publications

X-ray emission from the M9 dwarf 1RXS J115928.5-524717. Quasi-quiescent coronal activity at the end of the main-sequence

Schmitt, J. H. M. M.; Robrade, J.

Aims: X-ray emission is an important diagnostic for studying magnetic activity in presumably fully convective, very low-mass stars with virtually neutral photospheres.
Methods: We analyse an XMM-Newton observation of 1RXS J115928.5-524717, an ultracool dwarf with spectral type M9, and compare its X-ray properties to those of other similar very…

The Hipparcos catalog. Commentary on: Perryman M. A. C., Lindegren L., Kovalevsky J., et al., 1997, A&A, 323, L49

van Leeuwen, F.

On the origin of reverse polarity patches found by Hinode in sunspot penumbrae

Ichimoto, K.; Sánchez Almeida, J.

Context: The topology of penumbral magnetic fields is poorly known. The satellite Hinode has recently revealed penumbral structures of a magnetic polarity that is opposite to the main sunspot polarity. They may be direct confirmation that magnetic field lines and mass flows return to the solar interior throughout the penumbra, a configuration prev…

Radial distribution of near-UV flux in disc galaxies in the range 0 ⪉ z ⪉ 1

Beckman, J. E.; Trujillo, I.; Azzollini, R.

Context: In the last 8 Gyr of cosmic time the global star formation rate (SFR) has declined by roughly an order of magnitude, and most of this activity has been progressively confined to ever less massive galaxies (“downsizing”). Previous studies show that the main drivers of the decline in the global SFR are the spiral galaxies. However, we still…

Pulsed thermal emission from the accreting pulsar XMMU J054134.7-682550

Audard, M.; Walter, R.; Lanz, T. +1 more

Aims: Soft X-ray excesses have been detected in several Be/X-ray binaries and interpreted as the signature of hard X-ray reprocessing in the inner accretion disk. The system XMMU J054134.7-682550, located in the LMC, featured a giant Type II outburst in August 2007. The geometry of this system can be understood by studying the response of the soft…

The low-mass stellar-mass functions of rich, compact clusters in the Large Magellanic Cloud

de Grijs, R.; Hu, Y.; Liu, Q. +2 more

Context: The LMC is an ideal environment for studying stellar MFs, because it contains a large population of compact clusters at different evolutionary stages. We aim to obtain constraints on the initial MFs (IMFs) of our sample clusters on the basis of their present-day MFs, combined with our understanding of their dynamical and photometric evolu…

Weak lensing density profiles and mass reconstructions of the galaxy clusters Abell 1351 and Abell 1995

Dahle, H.; Schirmer, M.; Holhjem, K.

Aims: The aim of the present work is to study the overall mass distribution of the galaxy clusters Abell 1351 and Abell 1995 using weak gravitational lensing. These clusters have a very different mass structure and dynamical state and are the two extremes from a larger sample of 38 X-ray luminous clusters of similar size and redshift.
Methods:…

On the massive star content of the nearby dwarf irregular Wolf-Rayet galaxy IC 4662

Crowther, P. A.; Bibby, J. L.

Aims: We investigate the massive stellar content of the nearby dwarf irregular Wolf-Rayet galaxy IC 4662, and consider its global star forming properties in the context of other metal-poor galaxies, namely the SMC, IC 10 and NGC 1569.
Methods: Very Large Telescope/FORS2 imaging and spectroscopy plus archival Hubble Space Telescope/ACS imaging …

Bursting behavior of the Galactic center faint X-ray transient GRS 1741.9-2853

Grosso, N.; Porquet, D.; Bozzo, E. +6 more

Aims: The neutron star low-mass X-ray binary GRS 1741.9-2853 is a known type-I burster at the Galactic center. It is transient, faint, and located in a very crowded region, only 10' from the supermassive black hole Sgr A^star. Therefore, its bursting behavior has been poorly studied so far. In particular, its persistent emission has rarely been de…

The very short supersoft X-ray state of the classical nova M31N 2007-11a

Della Valle, M.; Pietsch, W.; Haberl, F. +9 more

Context: Short supersoft X-ray source (SSS) states (durations ≤100 days) of classical novae (CNe) indicate massive white dwarfs that are candidate progenitors of supernovae type Ia.
Aims: We carry out a dedicated optical and X-ray monitoring program of CNe in the bulge of M 31.
Methods: We discovered M31N 2007-11a and determined its optica…