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Star-forming Regions (star-forming + regions)
Selected AbstractsA shallow though extensive H2 2.122-,m imaging survey of Taurus,Auriga,Perseus , I. NGC 1333, L1455, L1448 and B1MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2008C. J. Davis ABSTRACT We discuss wide-field near-infrared (near-IR) imaging of the NGC 1333, L1448, L1455 and B1 star-forming regions in Perseus. The observations have been extracted from a much larger narrow-band imaging survey of the Taurus,Auriga,Perseus complex. These H2 2.122-,m observations are complemented by broad-band K imaging, mid-IR imaging and photometry from the Spitzer Space Telescope, and published submillimetre CO J= 3,2 maps of high-velocity molecular outflows. We detect and label 85 H2 features and associate these with 26 molecular outflows. Three are parsec-scale flows, with a mean flow lobe length exceeding 11.5 arcmin. 37 (44 per cent) of the detected H2 features are associated with a known Herbig,Haro object, while 72 (46 per cent) of catalogued HH objects are detected in H2 emission. Embedded Spitzer sources are identified for all but two of the 26 molecular outflows. These candidate outflow sources all have high near-to-mid-IR spectral indices (mean value of ,, 1.4) as well as red IRAC 3.6,4.5 ,m and IRAC/MIPS 4.5,24.0 ,m colours: 80 per cent have [3.6],[4.5] > 1.0 and [4.5],[24] > 1.5. These criteria , high , and red [4.5],[24] and [3.6],[4.5] colours , are powerful discriminants when searching for molecular outflow sources. However, we find no correlation between , and flow length or opening angle, and the outflows appear randomly orientated in each region. The more massive clouds are associated with a greater number of outflows, which suggests that the star formation efficiency is roughly the same in each region. [source] The dust temperatures of the pre-stellar cores in the , Oph main cloud and in other star-forming regions: consequences for the core mass functionMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007Dimitris Stamatellos ABSTRACT We estimate the dust temperatures of the clumps in the , Oph main cloud taking into account the 3D geometry of the region, and external heating from the interstellar radiation field and from HD 147879, a nearby luminous B2V star, which is believed to dominate the radiation field in the region. We find that the regions where pre-stellar cores are observed (i.e. at optical visual extinctions >7 mag) are colder than ,10 ,11 K. These dust temperatures are smaller than those which previous studies of the same region have assumed. We use the new dust temperatures to estimate the masses of the pre-stellar cores in the , Oph main cloud from millimetre observations, and we find core masses that are larger than previous estimates by a factor of ,2 ,3. This affects the core mass function (CMF) of the region; we find that the mass at which the core mass spectrum steepens from a slope ,, 1.5 to a slope ,, 2.5 has moved from ,0.5 to ,1 M,. In contrast with the CMF in other star-forming regions (e.g. Orion), there is no indication for a turnover down to the completeness limit (,0.2 M,), but the CMF may flatten at around ,0.4 M,. We generalize our results to the pre-stellar cores in Taurus and in Orion. In Taurus, the ambient radiation field heating the pre-stellar cores is believed to be weaker than that in , Oph. Hence, the dust temperatures of the cores in Taurus are expected to be below ,10 ,11 K. In Orion, the radiation field is believed to be 103 times stronger than the standard interstellar radiation field. Based on this assumption, we estimate that the dust temperatures of the pre-stellar cores in Orion are around ,20 ,30 K. [source] New photometric and spectroscopic observations of the Seyfert galaxy Mrk 315MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2005S. Ciroi ABSTRACT We present new important results about the intermediate-type Seyfert galaxy Mrk 315, recently observed through optical imaging and integral-field spectroscopy. Broad-band images were used to study the morphology of the host galaxy, narrow-band H, images to trace the star-forming regions, and middle-band [O iii] images to evidence the distribution of the highly ionized gas. Some extended emission regions were isolated and their physical properties studied by means of flux-calibrated spectra. High-resolution spectroscopy was used to separate different kinematic components in the velocity fields of gas and stars. Some peculiar features characterize this apparently undisturbed and moderately isolated active galaxy. Such features, already investigated by other authors, are re-analysed and discussed in the light of these new observations. The most relevant results we obtained are: the multitiers structure of the disc; the presence of a quasi-ring of regions with star formation much higher than previous claims; a secondary nucleus confirmed by a stellar component kinematically decoupled by the main galaxy; a new hypothesis about the controversial nature of the long filament, initially described as hook shaped, and more likely made of two independent filaments caused by interaction events between the main galaxy and two dwarf companions. [source] Toru, 6-cm polarimetry of the MilkyWayASTRONOMISCHE NACHRICHTEN, Issue 5-6 2006S. Ry Abstract We present first results of a radio continuum and polarization survey of the Milky Way at 4.7 GHz carried out with the 32-m radio telescope in Toru,. The survey is much less affected by depolarization effects than previous measurements at lower frequencies. This enables the study of magnetic field structure and its interrelations with particular features in the interstellar medium to much larger distances from the Sun. Our preliminary total power map shows a good association of radio features with galactic star-forming regions while the polarization data reveal an increasing coherence of magnetic fields away from the Galaxy's mid-plane. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||