Search

H  i observations of the nearby blue compact dwarf galaxy IC 10 obtained with the Dominion Radio Astrophysical Observatory synthesis telescope, for a total integration of ∼1000 h, are presented. We confirm the NW faint 21 cm H  i emission feature discovered in Green Bank Telescope (GBT) observations. The H  i feature has an H  i mass of 4.7 × 105 M⊙, which is only ∼0.6  |${{\ \rm per\ cent}}$| of the total H  i mass of the galaxy (7.8 × 107 M⊙). In the inner disc, the rotation curve of IC 10 rises steeply, then flattens until the last point where it rises again, with a maximum velocity of 30 km s−1. Based on our mass models, the kinematics of the inner disc of IC 10 can be described without the need of a dark matter halo. However, this does not exclude the possible presence of dark matter on a larger scale. It is unlikely that the disturbed features seen in the outer H  i disc of IC 10 are caused by an interaction with M 31. Features seen from our simulations are larger and at lower surface density than can be reached by current observations. The higher velocity dispersions seen in regions where several distinct H  i features meet with the main core of IC 10 suggest that there is ongoing accretion. [ABSTRACT FROM AUTHOR]

The Local Group starburst galaxy IC 10 is the closest example of a blue compact galaxy. Here, we use optical gi imaging from Canada-France-Hawaii Telescope/MegaCam and near infrared JHK imaging from United Kingdom Infrared Telescope/Wide Field Camera to conduct a comprehensive survey of the structure of IC 10. We examine the spatial distribution of its resolved young, intermediate and old stellar populations to large radius and low effective surface brightness levels. Akin to other dwarfs with multiple populations of different ages, stellar populations of decreasing average age are increasingly concentrated in this galaxy. We find that the young, starbursting population and the asymptotic giant branch population are both offset from the geometric centre of the older red giant branch (RGB) population by a few hundred parsecs, implying that the younger star formation occurred significantly away from the centre of the galaxy. The RGB population traces an extended structure that is typical of blue compact galaxies, with an effective radius of ~5.75 arcmin (~1.25 kpc). These measurements show that IC 10 is much more extended than has previously been realized, and this blue compact galaxy is one of the most extended dwarf galaxies in the Local Group. The outermost isophotes of this galaxy are very regular in shape and essentially circular in morphology. Based on this analysis, we do not find any evidence to suggest that IC 10 has undergone a recent, significant, interaction with an unknown companion. [ABSTRACT FROM AUTHOR]

We present the results of medium-resolution spectroscopy of 28 globular clusters (GCs) in six nearby galaxies of different luminosities and morphological types, situated in M33 (15 objects), M31 (three), IC10 (four), UGCA86 (four), Holmberg IX (one) and DDO71 (one) obtained at the Special Astrophysical Observatory 6-m telescope. Measurements of Lick absorption line indices and comparison with Simple Stellar Population models enabled us to obtain their spectroscopic ages, metallicities and -element to Fe abundance ratios. We found that all old- and intermediate-age GCs in our sample have low metallicities dex. Metal-rich clusters are young and are preferentially found in galaxies more massive than . The least massive dwarfs of our sample, DDO71 and Holmberg IX, host one massive intermediate-age and one massive young metal-poor GC, respectively. [ /Fe] abundance ratios tend to be enhanced but closer to solar values for dwarf galaxies compared to GCs in more massive galaxies. We analyse the age–metallicity relation for GCs in our sample and others from the literature, and find that (1) there is a general trend for GCs in low surface brightness dwarf galaxies to be more metal-poor at a given age than GCs in more massive galaxies; (2) the GC metallicity spread is wider for more massive galaxies and (3) intermediate-age GCs in early-type dwarf galaxies are more metal-rich at any given age than those in irregular galaxies of similar luminosity. [ABSTRACT FROM AUTHOR]

We present the results of the first spectroscopic observations of two planetary nebula (PN) candidates in the Local Group dwarf irregular galaxy IC 10. Using several spectral classification diagrams, we show that the brightest PN candidate (PN 7) is not a PN, but rather a compact H ii region consisting of two components with low electron number densities. After the rejection of this PN candidate, the IC 10 PN luminosity function cut-off becomes very close to the standard value. With the compiled spectroscopic data for a large number of extragalactic PNe, we analyse a series of diagnostic diagrams to generate quantitative criteria for separating PNe from unresolved H ii regions. We show that, with the help of the diagnostic diagrams and the derived set of criteria, PNe can be distinguished from H ii regions with an efficiency of ∼99.6 per cent. With the obtained spectroscopic data, we confirm that another, 1.7 mag fainter PN candidate (PN 9) is a genuine PN. We argue that, based on all currently available PNe data, IC 10 is located at a distance of 725+63−33 kpc [distance modulus ]. [ABSTRACT FROM AUTHOR]

We present an X-ray study of our nearest starburst galaxy IC 10, based on XMM–Newton and Chandra observations. A list of 73 XMM–Newton and 28 Chandra detections of point-like X-ray sources in the field is provided; a substantial fraction of them are likely stellar objects in the Milky Way due to the low Galactic latitude location of IC 10. The brightest source in the IC 10 field, X-1, has a mean 0.3–8.0 keV luminosity of and shows a large variation by a factor of up to ∼6 on time-scales of ∼104 s during the XMM–Newton observation. The X-ray spectra of the source indicate the presence of a multicolour blackbody accretion disc with an inner disc temperature . These results are consistent with the interpretation of the source as a stellar mass black hole (BH), probably accreting from a Wolf–Rayet (W–R) star companion. We infer the mass of this BH to be if it is not spinning, or a factor of up to ∼6 higher if there is significant spinning. We also detect an apparent diffuse soft X-ray emission component of IC 10. An effective method is devised to remove the X-ray CCD-readout streaks of X-1 that strongly affect the study of the diffuse component in the XMM–Newton and Chandra observations. We find that the diffuse X-ray morphology is oriented along the optical body of the galaxy and is chiefly associated with starburst regions. The diffuse component can be characterized by an optically thin thermal plasma with a mean temperature of and a 0.5–2 keV luminosity of , representing only a small fraction of the expected mechanical energy inputs from massive stars in the galaxy. There is evidence that the hot gas is driving outflows from the starburst regions; therefore, the bulk of the energy inputs may be released in a galactic wind. [ABSTRACT FROM AUTHOR]

Superbubbles are crucial for stellar feedback, with supposedly high (of the order of 10 per cent) thermalization rates. We combined multiband radio continuum observations from the Very Large Array (VLA) with Effelsberg data to study the non-thermal superbubble (NSB) in IC 10, a starburst dwarf irregular galaxy in the Local Group. Thermal emission was subtracted using a combination of Balmer Hα and VLA 32 GHz continuum maps. The bubble's non-thermal spectrum between 1.5 and 8.8 GHz displays curvature and can be well fitted with a standard model of an ageing cosmic ray electron population. With a derived equipartition magnetic field strength of 44 ± 8 μG, and measuring the radiation energy density from Spitzer MIPS maps as 5 ± 1 × 10−11 erg cm−3, we determine, based on the spectral curvature, a spectral age of the bubble of 1.0 ± 0.3 Myr. Analysis of the LITTLE THINGS H i data cube shows an expanding H i hole with 100 pc diameter and a dynamical age 3.8 ± 0.3 Myr, centred to within 16 pc on IC 10 X-1, a massive stellar mass black hole (M > 23 M⊙). The results are consistent with the expected evolution for a superbubble with a few massive stars, where a very energetic event like a Type Ic supernova/hypernova has taken place about 1 Myr ago. We discuss alternatives to this interpretation. [ABSTRACT FROM PUBLISHER]

The nature of the synchrotron superbubble in the IC 10 galaxy is discussed using the results of our investigation of its ionized gas structure, kinematics and emission spectrum from observations made with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences, and based on our analysis of the radio emission of the region. The hypernova explosion is shown to be a more plausible mechanism of formation of the synchrotron superbubble compared with the earlier proposed model of multiple supernova explosions. A compact remnant of this hypernova may be identified with the well-known X-ray binary X-1 – an accreting black hole. [ABSTRACT FROM AUTHOR]