8/5/2023 0 Comments Kspectra for windows![]() Error bars show the width of the distribution in each bin. The last two bins are wider to have enough stars per bin. The number of stars in each proper motion bin is given at the top. Mean distances of nearby stars (from Gliese & Jahreiß 1991) with 10% accurate parallaxes vs. ![]() This motivated our HPM search for cool brown dwarfs in the immediate solar neighbourhood using the preliminary WISE data release combined with the previous near-infrared (2MASS) and deep optical (SDSS) surveys. However, seven out of ten HPM late-T dwarfs with μ > 1 arcsec/yr fall in the 10 pc sample, whereas the other three are very close to the 10 pc horizon. Compared to 912 nearby stars shown with their mean values, only a few (34) late-T dwarfs are available with parallax measurements. HPM stars with μ > 1 arcsec/yr typically lie within 10 pc. Figure 1 shows the correlation between proper motion and parallax. 2011).Īs for the nearest stars in the catalogue of Gliese & Jahreiß ( 1991), we expect the nearest cool brown dwarfs to be high proper motion (HPM) objects. 2006) and the ongoing Sloan Digital Sky Survey with its two recent data releases (SDSS DR7, Abazajian et al. It allows the detection of nearby cool brown dwarfs (spectral types >T5) with much higher efficiency than the existing Two Micron All Sky Survey (2MASS Skrutskie et al. 2010) observed the sky in four infrared bands ( w1 at 3.4 μm, w2 at 4.6 μm, w3 at 12 μm, and w4 at 22 μm). The Wide-field Infrared Survey Explorer (WISE Wright et al. From their bright WISE w2 magnitudes of 12.7 and 12.3, we estimate distances of 5.5 pc and 4.6 pc and tangential velocities of ~65 km s -1 and ~34 km s -1 that indicate Galactic thick and thin disk membership, respectively.īased on observations with the Large Binocular Telescope (LBT). We confirm WISE J1741+2553 as a T9-T10 dwarf from near-infrared spectroscopy with LBT/LUCIFER1. With their w1 − w2 ~ 3.0 and J − w2 ~ 4.0 colour indices, we expect both to have spectral types of ~T8-T10 and absolute magnitude of M w2 ~ 14. We have identified two new ultracool brown dwarfs with large proper motions, WISE J0254+0223 (2.5 arcsec/yr) and WISE J1741+2553 (1.5 arcsec/yr). We used the preliminary data release from WISE, then selected bright candidates with colours typical of late-T dwarfs, and tried to match them with faint 2MASS and SDSS objects, to determine their proper motions, and to follow them up spectroscopically. We search for the nearest representatives of the coolest brown dwarfs, which will be very interesting for detailed follow-up observations, once they have been discovered. WISE provides an infrared all-sky survey that aims at completing our knowledge on the possibly dramatically increasing number of brown dwarfs with lower temperatures. Leibniz-Institut für Astrophysik Potsdam (AIP),Īims.
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