* Astronomy

Blobrana · L

RE: WISE J0254+0223 and WISE J1741+2553

Blobrana · L

Two new brown dwarf Solar neighbours discovered

Scientists from the Leibniz Institute for Astrophysics Potsdam (AIP) have discovered two new brown dwarfs at estimated distances of only 15 and 18 light years from the Sun. For comparison: The next star to the Sun, Proxima, is located slightly more than 4 light years from the Sun, whereas the nearest known brown dwarfs, epsilon Indi Ba and Bb, also found at the AIP several years ago, are about 12 light years away.
Ralf-Dieter Scholz and his AIP colleagues used the recently published data of the NASA satellite WISE (Wide-field Infrared Survey Explorer) for their discovery. The two new Solar neighbours, named WISE J0254+0223 and WISE J1741+2553, attracted attention by the extreme contrast between their strong brightness in the infrared and their almost invisible appearance in optical light. In addition, both objects move at comparably large speed across the sky (proper motion), i.e. their positions are remarkably different with respect to earlier observations.
Read more

Blobrana · L

Title: Two very nearby (d ~ 5 pc) ultracool brown dwarfs detected by their large proper motions from WISE, 2MASS, and SDSS data
Authors: R.-D. Scholz, G. Bihain, O. Schnurr, J. Storm (Leibniz-Institut für Astrophysik Potsdam (AIP))

Aims: WISE provides an infrared all-sky survey which aims at completing our knowledge on the possibly dramatically increasing number of brown dwarfs with lower temperatures. We search for the nearest representatives of the coolest brown dwarfs, which will be very interesting for detailed follow-up observations, once they haven been discovered.
Methods: We have used the preliminary data release from WISE, selected bright candidates with colours typical of late-T dwarfs, tried to match them with faint 2MASS and SDSS objects, to determine their proper motions, and to follow-up them spectroscopically.
Results: We have identified two new ultracool brown dwarfs, WISE J0254+0223 and WISE J1741+2553, with large proper motions of about 2.5 and 1.5 arcsec/yr, respectively. With their w1-w2~3.0 and J-w2~4.0 colour indices we expect them both to have a spectral type of ~T9-T10 and absolute magnitude of M_{w2}~14. For WISE J1741+2553 we confirm a spectral type of T10 from near-infrared spectroscopy with LBT/LUCIFER1. From their bright WISE w2 magnitudes of 12.7 and 12.3, we estimate distances of about 5.5 pc and 4.6 pc and tangential velocities of ~65 km/s and ~34 km/s indicating Galactic thick and thin disk membership, respectively.

Read more (782kb, PDF)