Identifying birth places of young isolated neutron stars

Abstract

Young isolated radio-quiet neutron stars are still hot enough to be detectable at X-ray and optical wavelengths due to their thermal emission and can hence probe cooling curves. An identification of their birth sites can constrain their age. For that reason we try to identify the parent associations for four of the so-called Magnificent Seven neutron stars for which proper motion and distance estimates are available. We are tracing back in time each neutron star and possible birth association centre to find close encounters. The associated time of the encounter expresses the kinematic age of the neutron star which can be compared to its characteristic spin-down age. Owing to observational uncertainties in the input data, we use Monte-Carlo simulations and evaluate the outcome of our calculations statistically. RX J1856.5-3754 most probably originated from the Upper Scorpius association about 0.3 Myr ago. RX 0720.4-3125 was either born in the young local association TWA about 0.4 Myr ago or in Tr 10 0.5 Myr in the past. Also RX J1605.3+3249 and RBS 1223 seem to come from a nearby young association such as the Sco-Cen complex or the extended Corona-Australis association. For RBS 1223 also a birth in Sct OB2 is possible. We also give constraints on the observables as well as on the radial velocity of the neutron star. Given the birth association, its age and the flight time of the neutron star, we estimate the mass of the progenitor star. Some of the potential supernovae were located very nearby (<100pc) and thus should have contributed to the 10Be and 60Fe material found in the Earth's crust. In addition we reinvestigate the previously suggested neutron star/ runaway pair PSR B1929+10/ zeta Ophiuchi and conclude that it is very likely that both objects were ejected during the same supernova event.Comment: 14 figures, 13 table

Direct detection of a substellar companion to the young nearby star PZ Telescopii

“…Because of its space motion ([U, V, W] = [−10.6, −15.4, −7.9]km s −1 ) and its other youth indicators, Zuckerman et al (2001) and Torres et al (2006) proposed that PZ Tel is a member of the β Pic moving group, with an age of 12 +8 −4 Myr. Tetzlaff et al (2010) determined the age of PZ Tel by comparing its luminosity and temperature with several theoretical model isochrones yielding an age of 12.8 ± 2.2 Myr, consistent with the general age estimate for the β Pic moving group. Rebull et al (2008) reported the detection of excess emission in the spectral energy distribution of PZ Tel at 70 μm with MIPS/Spitzer.…”

THE FIRST SPECTROPOLARIMETRIC MONITORING OF THE PECULIAR O4 Ief SUPERGIANT ζ PUPPIS

“…It was suggested that the fields are either "fossil" remnants of the Galactic ISM field, which is amplified during the collapse of a magnetized gas cloud (e.g., Price & Bate 2007), or that they are formed in a dramatic close binary interaction, i.e., in a merger of two stars or a dynamical mass transfer event (e.g., Ferrario et al 2009). Tetzlaff et al (2010) reinvestigated the scenario of a binary SN in Upper Scorpius involving ζ Oph and PSR B1929+10 and concluded that it is very likely that both objects were ejected during the same supernova event. Although in the case of ζ Oph binary interaction is expected, no significant field was detected in this star.…”

On the origin of LS 5039 and PSR J1825−1446

“…Forbes (2000) provides a distance to the association of 1.9 ± 0.3 kpc, and an average age of 5 ± 1 Myr. Tetzlaff et al (2010) provide a parallax measurement based on Hipparcos stars of 0.63 mas, which correspond to a distance from the Sun of 1.6 kpc and sets an age of the association of 4-5 Myr. On the other hand, the open cluster in the centre of region #2 is NGC 6604, which can be found in the WEBDA catalogue, with a distance of 1.7 kpc, and an age of ∼6 Myr.…”