منابع مشابه
X - ray spectral variability of the nucleus of M 81
We have analysed the soft X-ray emission from the nuclear source of the nearby spiral galaxy M 81, using the available data collected with ROSAT, ASCA, BeppoSAX and Chandra. The source flux is highly variable, showing (sometimes dramatic: a factor of 4 in 20 days) variability at different timescales, from 2 days to 4 years, and in particular a steady increase of the flux by a factor of 2 over 4...
متن کاملIdentification of molecular complexes in M 81
We report about high spatial resolution observations made with the IRAM Plateau de Bure interferometer of the 12CO(J = 1 → 0) emission from a 1.1 × 1.1 kpc plane-of-sky field on a spiral arm of Messier 81. With a beam of 5′′ ≈ 90 pc, we identify 6 giant molecular cloud complexes with virial masses of ≈ 106 M , including one associated with a giant HII region. The deduced N (H2)/ICO ratios are a...
متن کاملUltra - luminous M 81 X - 9 source : 20 years variability and spectral states
The source X-9 was discovered with the Einstein Observatory in the field of M81, and is located in the dwarf galaxy Holmberg IX. X-9 has a 0.2-4.0 keV luminosity of ∼ 5.5 × 10 39 ergs s −1 , if it is at the same distance as Holmberg IX (3.4 Mpc). This luminosity is above the Eddington luminosity of a 1 M ⊙ compact accreting object. Past hypotheses on the nature of this Super-Eddington source in...
متن کاملOne - sided Jet in the Center of M 81
The nucleus of the nearby spiral galaxy M81 was observed at 8.3 GHz with a global VLBI array at 20 epochs over four and a half years, with a linear resolution at the source of about 2000 AU or 0.01 pc. Phase-referenced mapping with respect to the geometric center of supernova 1993J in the same galaxy enabled us to find, with a standard error of about 600 AU, a stationary point in the source sou...
متن کاملTracing spiral density waves in M 81
We use SPITZER IRAC 3.6 and 4.5μm near infrared data from the Spitzer Infrared Nearby Galaxies Survey (SINGS), optical B, V and I and 2MASS Ks band data to produce mass surface density maps of M81. The IRAC 3.6 and 4.5μm data, whilst dominated by emission from old stellar populations, is corrected for small-scale contamination by young stars and PAH emission. The I band data are used to produce...
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ژورنال
عنوان ژورنال: Astronomy & Astrophysics
سال: 2006
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361:20066383