学术文献库

Within a 400~pc sphere around the Sun, we search for members of the Pisces-Eridanus (Psc-Eri) stellar stream in the Gaia Data Release 2 (DR2) data set. We compare basic astrophysical characteristics of the stream with those of the Pleiades. We used a modified convergent-point method to identify stars with 2D - velocities consistent with the space velocity of the Psc-Eri stream and the Pleiades, respectively. We found 1387 members of the Psc-Eri stream in a G magnitude range from 5.1 mag to 19.3 mag at distances between 80 and 380 pc from the Sun. The stream has a nearly cylindrical shape with length and thickness of about 700 pc and 100 pc, respectively. The total stellar mass contained in the stream is about 770 M_Sun, and the members are gravitationally unbound. For the stream we found an age of about 135 Myr. In many astrophysical properties Psc-Eri is comparable to the open cluster M45 (the Pleiades): in its age, its luminosity function (LF), its Present-day mass Function (PDMF) as well as in its total mass. Nonetheless, the two stellar ensembles are completely unlike in their physical appearance. We cautiously give two possible explanations for this disagreement: (i) the star-formation efficiency in their parental molecular clouds was higher for the Pleiades than for Psc-Eri or/and (ii) the Pleiades had a higher primordial mass segregation immediately after the expulsion of the molecular gas of the parental cloud.