We present K-band (2.2 m) imaging polarimetry that resolves 19 T Tauri binary and multiple systems in the Taurus-Auriga and Scorpius-Ophiuchus star-forming regions. We observed systems with projected separations 1B5-7B2 ($200-1000 AU) in order to determine the relative orientation of the circumstellar disks in each binary system. Scattered light from these disks is polarized, allowing us to deduce the position angle of the disk on the sky from the position angle of polarization even though our observations do not resolve the disks themselves. We detected measurable polarization (typically 0.5%-2%, with typical uncertainty 0.1%) from both stars in 14 of the systems observed. In eight of the nine binary systems, the two stars' polarization position angles are within 30 of each other, inconsistent with random orientations. In contrast, the five triple and quadruple systems appear to have random disk orientations when comparing the polarization position angles of the widest pair in the system; the close pairs are unresolved in all but one system. Our observations suggest that disks in wide (200-1000 AU) binaries are aligned with each other within P20 but not perfectly coplanar. However, we cannot conclusively rule out random relative disk orientations if the observed polarizations are significantly contaminated by interstellar polarization. Even in the presence of interstellar polarization our observations securely exclude coplanar disks. These results provide constraints on possible binary formation mechanisms if the observed orientations are primordial. On the other hand, models of disk-binary interactions indicate that the disks may have had time to decrease their relative inclinations since formation. If the common orientation of the disks in these binaries is a tracer of the binary orbital plane, then our results also have significance for the stability of planetary orbits, suggesting that planetary systems in wide binaries should be stable over 10 9 yr timescales.
We report the precise optical and X-ray localization of the 3.2 ms accretion-powered X-ray pulsar XTE J1814−338 with data from the Chandra X-Ray Observatory as well as optical observations conducted during the 2003 June discovery outburst. Optical imaging of the field during the outburst of this soft X-ray transient reveals an R = 18 star at the X-ray position. This star is absent (R > 20) from an archival 1989 image of the field and brightened during the 2003 outburst, and we therefore identify it as the optical counterpart of XTE J1814−338. The best source position derived from optical astrometry is R.A. = 18 h 13 m 39. s 04, Dec.= −33 • 46 ′ 22. ′′ 3 (J2000). The featureless X-ray spectrum of the pulsar in outburst is best fit by an absorbed power-law (with photon index γ = 1.41 ± 0.06) plus blackbody (with kT = 0.95 ± 0.13 keV) model, where the blackbody component contributes approximately 10% of the source flux. The optical broad-band spectrum shows evidence for an excess of infrared emission with respect to an X-ray heated accretion disk model, suggesting a significant contribution from the secondary or from a synchrotron-emitting region. A follow-up observation performed when XTE J1814−338 was in quiescence reveals no counterpart to a limiting magnitude of R = 23.3. This suggests that the secondary is an M3 V or later-type star, and therefore very unlikely to be responsible for the soft excess, making synchroton emission a more reasonable candidate.
An exceptionally intense gamma-ray burst, GRB 030329, was detected and localized by the instruments on board the High Energy Transient Explorer satellite (HETE ) at 11:37:14 UT on 2003 March 29. The burst consisted of two $10 s pulses of roughly equal brightness and an X-ray tail lasting more than 100 s. The energy fluence in the 30-400 keV energy band was S ¼ 1:2 ; 10 À4 ergs cm À2 , making GRB 030329 one of the brightest GRBs ever detected. Communication of a 2 0 error box 73 minutes after the burst allowed the rapid detection of a counterpart in the optical, X-ray, and radio and the ensuing discovery of a supernova with most unusual characteristics. Analyses of the burst light curves reveal the presence of a distinct, bright, soft X-ray component underlying the main GRB; the 2-10 keV fluence of this component is $7 ; 10 À6 ergs cm À2 . The main pulses of GRB 030329 were preceded by two soft, faint, nonthermal bumps. We present details of the HETE observations of GRB 030329.
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