2000/06/28 by L. D. Matthews · 58 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Bulge #Disc #Galaxies: Formation, Evolution, Phenomena #Galaxy #RADIUS #Scale height #Spiral galaxy #Stellar, planetary, and galactic studies #Surface brightness #Thick disk #Thin disk #astro-ph
paper · pdf · doi:10.1086/301555
published in The Astronomical Journal 120(4), 1764-1778 (Institute of Physics) · Accepted to the Astronomical Journal; 27 pages, 12 figures, 2 tables; Fig. 12 is in color
arxiv created 2000/06/28 · openalex publication_date 2000/10/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We explore the vertical light distribution as a function of galactocentric radius in the edge-on ( i = 88°) Sd "superthin" galaxy UGC 7321. UGC 7321 is a low-luminosity spiral ( M B , i = -17.0) with a diffuse, low surface brightness stellar disk and no discernible bulge component. Within ∼ 0 25 (∼725 pc) of the disk center the global luminosity profile of UGC 7321 can be reasonably characterized by an exponential function with a scale height h z ∼ 2 9 (∼140 pc) in H and h z ∼ 3 1 (∼150 pc) in R , making this among the thinnest galaxy disks known. Near the disk center we derive a ratio of disk scale length to global disk scale height h r / h z ∼ 14 in both H and R ; near the edge of the disk, h r / h z ∼ 10. At intermediate galactocentric radii (0 25 ≤ | r | ≤ 1 5), the disk of UGC 7321 becomes less peaked than an exponential near the galactic plane. At these radii the vertical luminosity profiles can be well reproduced by a linear combination of two isothermal disk components of differing scale heights. These fits, together with the strong disk color gradients by Matthews, Gallagher, & van Driel, suggest that UGC 7321 has multiple disk subcomponents comprised of stellar populations with different ages and velocity dispersions. Thus even examples of the thinnest pure disk galaxies exhibit complex structure and signatures of dynamical heating.