{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Structural Compon - Structural Compon Structural Components...

Info icon This preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Structural Compon Structural Components of Galaxies Several morphologically (and sometimes kinematically) distinct components emerge from the images of galaxies: for disk galaxies, these may include nucleus, bulge, lens, and disk. The disk may itself contain arms, a bar, rings, and other embellishments. The relative roles of these in some cases change with Hubble type. Some of these (i.e. disk-bulge luminosity ratio) were discussed by de Vaucouleurs (1977, Yale Conf. p. 43) under the rubric of "quantitative classification". Photometric Bulge and Disk Components: For S0 and spiral galaxies, we may broadly consider a disk and a central bulge. The disk is quite thin both in stars and gas (when present), with aspect ratio 10 or greater (beware photographic and visual effects in getting such numbers from pictures, however - the "real" axial ratio seldom exceeds 6). The bulge is more nearly spherical, though it is sometimes found to be a (triaxial) ellipsoid like a very stubby bar. A "classical" approach to separating the bulge and disk
Image of page 1
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern