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Research On Astrophysics Discussed By A.A. Hakobyan And Co-Researche

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  • Research On Astrophysics Discussed By A.A. Hakobyan And Co-Researche

    RESEARCH ON ASTROPHYSICS DISCUSSED BY A.A. HAKOBYAN AND CO-RESEARCHERS

    Science Letter
    February 2, 2010

    According to recent research from Armenia, "With the goal of providing
    constraints on the nature of the progenitors of core-collapse (CC)
    supernovae (SNe), we compare their radial distribution within their
    spiral host galaxies with the distributions of stars and ionized gas
    in spiral disks. SNe positions are taken from the Asiago catalog for
    a well-defined sample of 224 SNe within 204 host galaxies."

    "The SN radial distances are estimated from the deprojected separations
    from the host galaxy nuclei, and normalized both to the 25th mag
    arcsec(-2) blue-band isophotal radius and (for the first time)
    to the statistically-estimated disk scale length. The normalized
    radial distribution of all CCSNe is consistent with an exponential
    law, as previously found, with a possible depletion of CCSNe within
    one-fifth of the isophotal radius (less significant with scale-length
    normalization). There are no signs of truncation of the exponential
    distribution of CCSNe out to 7 disk scale lengths. The scale length
    of the distribution of type II SNe appears to be significantly larger
    than that of the stellar disks of their host galaxies, but consistent
    with the scale lengths of Freeman disks. SNe Ib/c have a significantly
    smaller scale length than SNe II, with little difference between types
    Ib and Ic. The radial distribution of type Ib/c SNe is more centrally
    concentrated than that of the stars in a Freeman disk, but is similar
    to the stellar disk distribution that we infer for the host galaxies.

    All CCSN subsamples are consistent with the still uncertain
    distribution of H II regions. The scale length of the CCSN radial
    distribution shows no significant correlation with the host galaxy
    morphological type, or the presence of bars. However, low luminosity as
    well as inclined hosts have a less concentrated distribution (with the
    scale-length normalized radial distances) of CCSNe, which are probably
    a consequence of metallicity and selection effects, respectively. The
    exponential distribution of CCSNe shows a scale length consistent with
    that of the ionized gas confirming the generally accepted hypothesis
    that the progenitors of these SNe are young massive stars," wrote
    A.A. Hakobyan and colleagues (see also Astrophysics).

    The researchers concluded: "Given the lack of correlation of the
    normalized radial distances of CCSNe with the morphological type of
    the host galaxy, we conclude that the more concentrated distribution
    of SNe Ib/c relative to SNe II must arise from the higher metallicity
    of their progenitors or possibly from a shallower initial mass function
    in the inner regions of spirals."

    Hakobyan and colleagues published their study in Astronomy &
    Astrophysics (The radial distribution of core-collapse supernovae
    in spiral host galaxies. Astronomy & Astrophysics, UNKNOWN
    DATE;508(3):1259-1268).

    For additional information, contact A.A. Hakobyan, Byurakan
    Astrophysics Observ, Armenian Branch, Byurakan 0213, Aragatzotn Prov,
    Armenia.

    Publisher contact information for the journal Astronomy & Astrophysics
    is: EDP Sciences S a, 17, Avenue du Hoggar, PA Courtaboeuf, BP 112,
    F-91944 les Ulis Cedex a, France.
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