A search for stars in the intergalactic neutral hydrogen cloud H I 1225 + 01: The star formation threshold in galaxies

N. J J Turner, A. MacFadyen

    Research output: Contribution to journalArticle

    Abstract

    H I 1225 + 01 is an intergalactic neutral hydrogen cloud in Virgo, made up of two main clumps. The north-east (NE) clump has a dwarf galaxy optical counterpart consisting of knots of stars about 5 × 5 arcsec2 and larger. Although the south-west (SW) clump has a peak H I column density similar to that of the NE clump, past V-band searches of the SW clump reveal no stars. However, stars remaining from a previous epoch of star formation would be more easily detected at infrared wavelengths. An I-band image of the SW clump is obtained and modal-filtered on a 5 × 5 arcsec2 box. The filtering yields a surface brightness limit for extended emission 2.8 mag arcsec-2 fainter than that in the original image. No extended emission is seen to a limiting surface brightness of 27.27 mag arcsec-2. This is about 4 I mag arcsec-2 fainter than the highest surface brightness portion of the dwarf galaxy in the NE clump. We discuss several ways to prevent the SW clump from forming stars, including photodissociation of its molecular hydrogen and gravitational interaction with the NE clump.

    Original languageEnglish (US)
    Pages (from-to)125-129
    Number of pages5
    JournalMonthly Notices of the Royal Astronomical Society
    Volume285
    Issue number1
    StatePublished - 1997

    Fingerprint

    hydrogen clouds
    clumps
    star formation
    hydrogen
    galaxies
    stars
    thresholds
    brightness
    dwarf galaxies
    wavelength
    extremely high frequencies
    photodissociation
    boxes
    time measurement

    Keywords

    • Galaxies: evolution
    • Galaxies: individual: H i 1225+ 01
    • Stars: formation

    ASJC Scopus subject areas

    • Space and Planetary Science

    Cite this

    A search for stars in the intergalactic neutral hydrogen cloud H I 1225 + 01 : The star formation threshold in galaxies. / Turner, N. J J; MacFadyen, A.

    In: Monthly Notices of the Royal Astronomical Society, Vol. 285, No. 1, 1997, p. 125-129.

    Research output: Contribution to journalArticle

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    AB - H I 1225 + 01 is an intergalactic neutral hydrogen cloud in Virgo, made up of two main clumps. The north-east (NE) clump has a dwarf galaxy optical counterpart consisting of knots of stars about 5 × 5 arcsec2 and larger. Although the south-west (SW) clump has a peak H I column density similar to that of the NE clump, past V-band searches of the SW clump reveal no stars. However, stars remaining from a previous epoch of star formation would be more easily detected at infrared wavelengths. An I-band image of the SW clump is obtained and modal-filtered on a 5 × 5 arcsec2 box. The filtering yields a surface brightness limit for extended emission 2.8 mag arcsec-2 fainter than that in the original image. No extended emission is seen to a limiting surface brightness of 27.27 mag arcsec-2. This is about 4 I mag arcsec-2 fainter than the highest surface brightness portion of the dwarf galaxy in the NE clump. We discuss several ways to prevent the SW clump from forming stars, including photodissociation of its molecular hydrogen and gravitational interaction with the NE clump.

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    KW - Stars: formation

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