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Post Info TOPIC: Messier 81
Blobrana


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RE: Messier 81
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False-colour view of galaxy M81

An important part of studying celestial objects is understanding and removing the background noise.
The image presented here was created to demonstrate the power of software tools used to analyse observations by ESA's XMM-Newton of large objects like galaxies, clusters of galaxies, and supernova remnants. 
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Blobrana


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The Ghostly Remnants of Galaxy Interactions Uncovered in a Nearby Galaxy Group

Astronomers using the Subaru Telescope's Hyper Suprime-Cam prime-focus camera recently observed the nearby large spiral galaxy M81, together with its two brightest neighbours, M82 and NGC3077. The results of their observations are deep, super wide-field images of the galaxies and their populations of young stars. As part of a Galactic Archaeology study, the team discovered that the spatial distribution of the young stars around these galaxies follows very closely that of their distribution of neutral hydrogen. 
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Blobrana


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NGC 3031
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NGC 3031 (also Bode's Galaxy or Messier 81) is a magnitude +6.9 spiral galaxy located 11.8 ±0.4 million light years away in the constellation Ursa Major.

The galaxy was discovered by German astronomer Johann Elert Bode at the Berlin observatory on the 31st December 1774.

The galaxy hosted Supernova 1993J

Messier 81 is the largest galaxy in the M81 Group, a group of 34 galaxies located in the constellation Ursa Major. At approximately 11.7 Mly (3.6 Mpc) from the Earth, it makes this group and the Local Group, containing the Milky Way, relative neighbours in the Virgo Supercluster.
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M81/NGC 3031 or Bode's Galaxy, zoom into

Spoiler

Right Ascension 09h 55m 34s, Declination +69° 04' 02"



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Blobrana


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Title: Jet precession in the active nucleus of M81. Ongoing VLBI monitoring
Authors: I. Marti-Vidal, J.M. Marcaide, A. Alberdi, A. Brunthaler

In a recent publication, we reported results of a multi-frequency VLBI campaign of observations of the Active Galactic Nucleus (AGN) in galaxy M 81, phase-referenced to the supernova SN 1993J. We were able to extract precise information on the relative astrometry of the AGN radio emission at different epochs and frequencies. We found strong evidence of precession in the AGN jet (i.e., a systematic evolution in the jet inclination at each frequency) coupled to changes in the overall flux density at the different frequencies. In these proceedings, we summarise the main contents of our previous publication and we report on (preliminary) new results from our follow-up VLBI observations, now phase-referenced to the young supernova SN2008iz. We also briefly discuss how these results match the picture of our previously-reported precession model.

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Blobrana


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Title: An Oxygen Abundance Gradient into the Outer Disk of M81
Authors: Maria T. Patterson, Rene A.M. Walterbos, Robert C. Kennicutt, Cristina Chiappini, David A. Thilker

The extended HI disk and tidal tails of M81 present an interesting environment to study the effects of galaxy interaction on star formation and chemical evolution of the outer disk of a large spiral galaxy. We present H{\alpha} imaging of the outer disk of M81 and luminosities for 40 HII regions out to about 3 times the optical radius. We have also obtained MMT spectra for 21 HII regions out to more than twice the optical radius. We derive strong line oxygen abundances for all HII regions using R_{23} based and [NII]/[OII] based calibrations and electron temperature abundances for seven regions spanning a galactocentric distance between 5.7 and 32 kpc. We also comment on the abundances of HII regions near KDG 61 and the "tidal dwarf" candidate HoIX. Our results constitute the most radially extended metallicity study for M81 to date. With this extended data set, we find an overall oxygen abundance gradient of -0.013 dex/kpc over the entire radial range. This is significantly flatter than what has been found in previous studies which were limited to the optical disk. From our temperature based abundances, we find a gradient of -0.020 dex/kpc and present the possibility of a broken gradient from these data, but note the need to obtain more temperature based abundances at intermediate galactocentric distances (~10-20 kpc) to verify whether or not this may be the case. We discuss our main result of a rather flat gradient for M81 in the context of simulations and observations of abundance gradients in other galaxies. We find that the shallow abundance gradient of M81 is likely a result of the interaction history of this galaxy.

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Blobrana


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Title: Detection of jet precession in the active nucleus of M81
Authors: I. Marti-Vidal, J. M. Marcaide, A. Alberdi, M. A. Perez-Torres, E. Ros, J. C. Guirado
(Version v3)

We report on VLBI monitoring of the low-luminosity AGN (LLAGN) in M81 at 1.7, 2.3, 5, and 8.4GHz. These observations are phase-referenced to the supernova SN1993J (located in the same galaxy) and cover from late 1993 to late 2005. The source consists at all frequencies of a slightly resolved core and a small jet extension towards the north-east direction (position angle of ~65 degrees) in agreement with previous publications. We find that the position of the intensity peak in the images at 8.4GHz is very stable in the galactic frame of M81 (proper motion upper limit about 0.010 mas per year). We confirm previous reports that the peaks at all frequencies are systematically shifted among them, possibly due to opacity effects in the jet as predicted by the standard relativistic jet model. We use this model to estimate the magnetic field in the jet and the mass of the central black hole. We obtain a black-hole mass of ~2.e+7 solar masses, comparable to estimates previously reported, but the magnetic fields obtained are thousands of times lower than previous estimates. We find that the positions of the cores at 1.7, 2.3, and 5GHz are less stable than that at 8.4GHz and evolve systematically, shifting southward at a rate of several tens of micro-arcsec per year. The evolution in the jet orientation seems to be related to changes in the inclination of the cores at all frequencies. These results can be interpreted as due to a precessing jet. The jet precession also seems to be related to a flare in the flux densities at 5.0 and 8.4GHz, which lasts ~4 years. A continued monitoring of the flux density and the jet structure evolution in this LLAGN will be necessary to further confirm our jet precession model.

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Partner Galaxies Wildly Different In New WISE Image

NASA's Wide-field Infrared Survey Explorer has captured a new view of two companion galaxies -- a somewhat tranquil spiral beauty and its rambunctious partner blazing with smoky star formation.
The unlikely pair, named Messier 81 and Messier 82, got to know each other a lot better during an encounter that occurred a few hundred million years ago. As they swept by each other, gravitational interactions triggered new bursts of star formation. In the case of Messier 82, also known as the Cigar galaxy, the encounter has likely triggered a tremendous wave of new star birth at its core. Intense radiation from newborn massive stars is blowing copious amounts of gas and smoky dust out of the galaxy, as seen in the WISE image in yellow hues.
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M81's "Halo" Sheds Light on Galaxy Formation

Observations with Subaru Telescope's Prime Focus Camera (Suprime-Cam) have revealed an extended structure of the spiral galaxy Messier 81 (M81) that may hold a key to understanding the formation of galaxies. This structure could be M81's halo. Until now, ground-based telescopes have only observed individual stars in the haloes around the Milky Way and Andromeda Galaxies. Differences in M81's extended structure from the Milky Way's halo may point to variations in the formation histories of spiral galaxies.
M81 is one of the largest galaxies in the M81 Group, a group of 34 galaxies located toward the constellation Ursa Major. At 11.7 million light years from Earth, it is one of the closest groups to the Local group, the group of galaxies that includes our own Milky Way. Thanks to its proximity and similarity to the Milky Way, M81 provides an excellent laboratory for testing galaxy formation models.
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Blobrana


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Here's another Astro pic for anyone interested, its of the Galaxies M81 (Centre of pic) M82 and the very faint NGC 3077 top left.
The sky was a bit clearer over the weekend so i managed to get a bit more detail in this pic than the last time i posted it.
These Galaxies are around 12 Million light years away, and were taken on my 3.1 inch refractor telescope
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M81
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Title: Resolving the Stellar Outskirts of M81: Evidence for a Faint, Extended Structural Component
Authors: M. K. Barker, A. M. N. Ferguson (Inst. for Astr., Edinburgh), M. Irwin (Inst. of Astr., Cambridge), N. Arimoto (Nat. Astr. Obs. of Japan), P. Jablonka (Geneva Obs.)

We present a wide field census of resolved stellar populations in the northern half of M81, conducted with Suprime-Cam on the 8-m Subaru telescope and covering an area ~ 0.3 square degrees. The resulting colour-magnitude diagram reaches over one magnitude below the red giant branch (RGB) tip, allowing a detailed comparison between the young and old stellar spatial distributions. The surface density of stars with ages <~ 100 Myr is correlated with that of neutral hydrogen in a manner similar to the disk-averaged Kennicutt-Schmidt relation. We trace this correlation down to gas densities of ~ 2 x 10^20 cm^{-2}, lower than typically probed with H-alpha flux. Both diffuse light and resolved RGB star counts show compelling evidence for a faint, extended structural component beyond the bright optical disk, with a much flatter surface brightness profile. The star counts allow us to probe this component to significantly fainter levels than is possible with the diffuse light alone. From the colours of its RGB stars, we estimate this component has a peak global metallicity [M/H] ~ -1.1 ±0.3 at deprojected radii 32 - 44 kpc assuming an age of 10 Gyr and distance of 3.6 Mpc. The spatial distribution of its RGB stars follows a power-law surface density profile, I(r) ~ r^{-gamma}, with gamma ~ 2.

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