The ringed spiral galaxy NGC 4622. I. Photometry, kinematics, and the case for two strong leading outer spiral arms

dc.contributor.authorButa, RJ
dc.contributor.authorByrd, GG
dc.contributor.authorFreeman, T
dc.contributor.otherUniversity of Alabama Tuscaloosa
dc.date.accessioned2019-06-19T17:49:29Z
dc.date.available2019-06-19T17:49:29Z
dc.date.copyright2003
dc.date.issued2003-02
dc.description.abstractThe intriguing nearly face-on southern ringed spiral galaxy NGC 4622, the first galaxy definitively shown to have leading spiral structure, is revisited in this paper with new images from the Hubble Space Telescopes (HST) WFPC2, together with ground-based optical and near-IR imaging, and a Fabry-Perot Halpha velocity field. The data provide new information on the disk/bulge/halo mix, rotation curve, star formation in the galaxy, and the sense of winding of its prominent spiral arms. Previously, we suggested that the weaker, inner single arm most likely has the leading sense, based on a numerical simulation. Now, taking advantage of HST resolution and using de Vaucouleurs standard extinction and reddening technique to determine the near side of the galaxy's slightly tilted disk, we come to the more surprising conclusion that the two strong outer arms have the leading sense. We suggest that this highly unusual configuration may be the result of a past minor merger or mild tidal encounter. Possible evidence for a minor merger is found in a short, central dust lane, although this is purely circumstantial and an unrelated interaction with a different companion could also be relevant. The leading arms may be allowed to persist because NGC 4622 is dark halo dominated (i.e., not maximum disk in the inner regions) and displays a significantly rising rotation curve. The new HST observations also reveal a rich globular cluster system in the galaxy. The mean color of these clusters is (V-I)(0) = 1.04, and the specific frequency is 3.4 +/- 0.6. The luminosity function of these clusters confirms the membership of NGC 4622 in the Centaurus Cluster.en_US
dc.format.mimetypeapplication/pdf
dc.identifier.citationButa, R., Byrd, G., Freeman, T. (2003): The Ringed Spiral Galaxy NGC 4622. I. Photometry, Kinematics, and the Case for Two Strong Leading Outer Spiral Arms. The Astronomical Journal, 125(2). DOI: 10.1086/345821
dc.identifier.doi10.1086/345821
dc.identifier.urihttp://ir.ua.edu/handle/123456789/5795
dc.languageEnglish
dc.language.isoen_US
dc.publisherIOP Publishing
dc.rights.holderAmerican Astronomical Society
dc.subjectgalaxies : kinematics and dynamics
dc.subjectgalaxies : photometry
dc.subjectgalaxies : spiral
dc.subjectgalaxies : structure
dc.subjectGLOBULAR-CLUSTER SYSTEMS
dc.subjectOPTICAL-ROTATION CURVES
dc.subjectHUBBLE-SPACE-TELESCOPE
dc.subjectSURFACE PHOTOMETRY
dc.subjectSA GALAXIES
dc.subjectDARK MATTER
dc.subjectLOCAL GROUP
dc.subjectDISKS
dc.subjectSOMBRERO
dc.subjectWFPC2
dc.subjectAstronomy & Astrophysics
dc.titleThe ringed spiral galaxy NGC 4622. I. Photometry, kinematics, and the case for two strong leading outer spiral armsen_US
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dc.typeArticle
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