Dusty Space CloudThis new image shows the Large Magellanic Cloud galaxy in infrared light as seen by the Herschel Space Observatory, a European Space Agency-led mission with important NASA contributions, and NASA's Spitzer Space Telescope. In the instruments' combined data, this nearby dwarf galaxy looks like a fiery, circular explosion.
Title: Large Magellanic Cloud Cepheids in the ASAS data Authors: P. Karczmarek, W. A. Dziembowski, P. Lenz, P. Pietrukowicz, G. Pojmanski A catalogue of Cepheids in the Large Magellanic Cloud (LMC) from the ASAS project is presented. It contains data on 65 fundamental mode pulsators with periods longer than about 8 days. The period-luminosity (PL) relation in the V-band does not significantly differ from the relation determined by Soszynski et al. (2008) from the OGLE data extended toward longer periods but with much larger spread. For objects with periods longer than 40 days there is an evidence for a shallower PL relation. The rates of long-term period variations significant at 3 sigma level are found only for 7 objects. The rates for 25 objects determined with the 1 sigma significance are confronted with the values derived from stellar evolution models. The models from various sources yield discrepant predictions. Over the whole data range, a good agreement with measurements is found for certain models but not from the same source. Read more (888kb, PDF)
Title: H.E.S.S. observations of the Large Magellanic Cloud Authors: Nu. Komin, A. Djannati-Ataï, Y. Gallant, V. Marandon, C.C. Lu, S. Ohm, E. de Oña Wilhelmi, for the H.E.S.S. collaboration The Large Magellanic Cloud (LMC) is a satellite galaxy of the Milky Way at a distance of approximately 48 kpc. Despite its distance it harbours several interesting targets for TeV gamma-ray observations. The composite supernova remnant N 157B/PSR J05367-6910 was discovered by H.E.S.S. being an emitter of very high energy (VHE) gamma-rays. It is the most distant pulsar wind nebula ever detected in VHE gamma-rays. Another very exciting target is SN 1987A, the remnant of the most recent supernova explosion that occurred in the neighbourhood of the Milky Way. Models for Cosmic Ray acceleration in this remnant predict gamma-ray emission at a level detectable by H.E.S.S. but this has not been detected so far. Fermi/LAT discovered diffuse high energy (HE) gamma-ray emission from the general direction of the massive star forming region 30 Doradus but no clear evidence for emission from either N 157B or SN 1987A has been published. The part of the LMC containing these objects has been observed regularly with the H.E.S.S. telescopes since 2003. With deep observations carried out in 2010 a very good exposure of this part of the sky has been obtained. The current status of the H.E.S.S. LMC observations is reported along with new results on N 157B and SN 1987A. Read more (1328kb, PDF)
NEIGHBOUR GALAXY CAUGHT STEALING STARSAstronomers from the National Optical Astronomy Observatory (NOAO) and their collaborators have found that hundreds of the stars found in the Large Magellanic Cloud (LMC) were stolen from another nearby galaxy - the Small Magellanic Cloud (SMC). The Large and Small Magellanic Clouds are both neighbour galaxies to our Milky Way Galaxy and easily visible to the unaided eye from the southern hemisphere.By analysing the spectra of 5900 giant and supergiant stars in the Large Magellanic Cloud galaxy, NOAO astronomers Knut Olsen and Bob Blum, and their collaborators Dennis Zaritsky (University of Arizona), and Martha Boyer and Karl Gordon (Space Telescope Science Institute) found that over 5% of the stars they observed in the LMC are rotating counter to the direction of the majority of LMC stars, or perhaps in a plane that is greatly inclined to the rotation of the LMC. An ambiguity remains in the result, because the astronomers were only able to measure the projection of the stellar velocities into the line of sight, and not their full velocity vectors. In either case, these peculiar orbits indicate that these stars probably did not form from the rotating and collapsing cloud of gas that formed the LMC, a galaxy located about 160,000 light years away.
Title: A Population of Accreted SMC Stars in the LMCAuthors: Knut A.G. Olsen, Dennis Zaritsky, Robert D. Blum, Martha L. Boyer, Karl D. GordonWe present an analysis of the stellar kinematics of the Large Magellanic Cloud based on ~5900 new and existing velocities of massive red supergiants, oxygen-rich and carbon-rich AGB stars, and other giants. After correcting the line-of-sight velocities for the LMC's space motion and accounting for asymmetric drift in the AGB population, we derive a rotation curve that is consistent with all of the tracers used, as well as that of published HI data. The amplitude of the rotation curve is v_0=87±5 km s^-1 beyond a radius R_0=2.4±0.1 kpc, and has a position angle of the kinematic line of nodes of theta=142 degrees ±5 degrees. By examining the outliers from our fits, we identify a population of 376 stars, or >~5% of our sample, that have line-of-sight velocities that apparently oppose the sense of rotation of the LMC disk. We find that these kinematically distinct stars are either counter-rotating in a plane closely aligned with the LMC disk, or rotating in the same sense as the LMC disk, but in a plane that is inclined by 54 degrees ±2 degrees to the LMC. Their kinematics clearly link them to two known HI arms, which have previously been interpreted as being pulled out from the LMC. We measure metallicities from the Ca triplet lines of ~1000 LMC field stars and 30 stars in the kinematically distinct population. For the LMC field, we find a median [Fe/H]=-0.56 ±0.02 with dispersion of 0.5 dex, while for the kinematically distinct stars the median [Fe/H] is -1.25 ±0.13 with a dispersion of 0.7 dex. The metallicity differences provide strong evidence that the kinematically distinct population originated in the SMC. This interpretation has the consequence that the HI arms kinematically associated with the stars are likely falling into the LMC, instead of being pulled out. Read more (1591kb, PDF)
Astronomers scanning the skies as part of ESO's VISTA Magellanic Cloud survey have now obtained a spectacular picture of the Tarantula Nebula in our neighbouring galaxy, the Large Magellanic Cloud. This panoramic near-infrared view captures the nebula itself in great detail as well as the rich surrounding area of sky. The image was obtained at the start of a very ambitious survey of our neighbouring galaxies, the Magellanic Clouds, and their environment.
The NASA/ESA Hubble Space Telescope captures a complex network of gas clouds and star clusters within our neighbouring galaxy, the Large Magellanic Cloud. This region of energetic star birth is one of the most active in the nearby Universe.The Large Magellanic Cloud contains many bright bubbles of glowing gas. One of the largest and most spectacular is LHA 120-N 11, from the catalogue compiled in 1956 by the late astronomer and astronaut Karl Henize. It is informally known as N11.Close up, N11's billowing pink clouds of glowing gas resemble a puffy swirl of fairground candyfloss. From further away, its distinctive overall shape led some observers to nickname it the Bean Nebula. The dramatic and colourful features in the nebula are the telltale signs of star birth.
They are more than a 100 times the mass of the Sun, glow more than 10 million times as brightly, and, over the course of their lives, spew out more than half their mass in the form of a relentless stellar wind. Yet the origin of the young massive stars in the Large Magellanic Cloud (LMC) galaxy has been a mystery for astronomers for decades.Vasilii Gvaramadze, an astronomer at the Sternberg Astronomical Institute at Moscow State University, and his colleagues have now located the birthplace of one of the group, and have shown that it is a 'runaway star', bolting across the LMC at more than 130 kilometres per second after being ejected from its home cluster. The discovery implies that other young massive stars in the LMC might also be runaways, and casts light on the violent processes that can cause giant stars to be ejected from the stellar clusters in which they first form.