نتایج جستجو برای: sgr 193031
تعداد نتایج: 3001 فیلتر نتایج به سال:
We report on the rapid X-ray variability of the variable star and X-ray transient V4641 Sagittarii (SAX J1819.3-2525 = XTE J1819-254) as observed on 1999 September 15 by the proportional counter array (PCA) on board the Rossi X-Ray Timing Explorer. During the first approximately 900 s of the first PCA observation, V4641 Sgr showed very strong X-ray fluctuations by a factor of 4 on timescales of...
Dynamical mass measurements to date have allowed determinations of the mass M and the distance D of a number of nearby supermassive black holes. In the case of Sgr A*, these measurements are limited by a strong correlation between the mass and distance scaling roughly as M ∼ D2. Future very long baseline interferometric (VLBI) observations will image a bright and narrow ring surrounding the sha...
Using Chandra data taken on 2008 June, we detected pulsations at 2.594 39(4) s in the soft gamma-ray repeater SGR 1627–41. This is the second measurement of the source spin period and allows us to derive for the first time a long-term spin-down rate of (1.9 ± 0.4) × 10 s s. From this value we infer for SGR 1627–41 a characteristic age of ∼2.2 kyr, a spin-down luminosity of ∼4 × 10 erg s (one of...
The MACHO Project has catalogued ∼ 8000 RR Lyrae stars in the Large Magellanic Cloud, ∼ 1800 in the Galactic bulge, and ∼ 50 in the Sgr dwarf galaxy. These variables are excellent distance indicators, and are used as tools to study the structure of the Large Magellanic Cloud and the bulge. The large datasets also probe uncommon pulsation modes. A number of double-mode RR Lyrae stars (RRd) are f...
The MACHO Project has catalogued 8000 RR Lyrae stars in the Large Magellanic Cloud, 1800 in the Galactic bulge, and 50 in the Sgr dwarf galaxy. These variables are excellent distance indicators, and are used as tools to study the structure of the Large Magellanic Cloud and the bulge. The large datasets also probe uncommon pulsation modes. A number of double-mode RR Lyrae stars (RRd) are found i...
We demonstrate that polarimetric interferometry can be used to extract precise spatial information about compact polarized flares of Sgr A∗. We show that, for a faint dynamical component, a single interferometric baseline suffices to determine both its polarization and projected displacement from the quiescent intensity centroid. A second baseline enables two-dimensional reconstruction of the d...
The latest Sloan Digital Sky Survey data reveal a prominent bifurcation in the distribution of debris of the Sagittarius dwarf spheroidal (Sgr) beginning at a right ascension of α ≈ 190. Two branches of the stream (A and B) persist at roughly the same heliocentric distance over at least 50 of arc. There is also evidence for a more distant structure (C) well behind the A branch. This paper provi...
We report the detection of radio QPOs with structure changes using the Very Long Baseline Array (VLBA) at 43 GHz. We found conspicuous patterned changes of the structure with P = 16.8, 22.2, 31.4,&56.4 min, roughly in a 3 : 4 : 6 : 10 ratio. The first two periods show a rotating one-arm structure, while the P = 31.4 min shows a rotating 3-arm structure, as if viewed edge-on. At the central 50μa...
We present new results based on high-resolution observations of Sgr A West at the Galactic center with the Very Large Array (VLA) at 1.3 cm. By combining recent observations with those made at earlier epochs with the VLA at wavelengths of 1.3 and 3.6 cm, we measured proper motions for 71 compact HII components in the central 80 (3 pc, assuming D = 8 pc). Using VLA archival data for the H92α rad...
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