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Near Infrared Star Counts as a Probe of Asymmetries in the Galaxy's Disk

Published online by Cambridge University Press:  25 May 2016

James E. Rhoads
James E. Rhoads*
Affiliation:
Princeton University Observatory, Princeton NJ 08544, USA. email: [email protected]

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I have recently started an observing program to study the distribution of dynamically old giant stars in the disk, looking for (i) large amplitude spiral arms and (ii) small amplitude corrugations.

  1. (i) Theoretical studies of spiral density waves usually assume that the mass density contrast is weak and the waves linear. Recent observations in red and near-IR light (e.g., Elmegreen and Elmegreen 1984; Rix and Zaritsky 1994), coupled with stellar population models, suggest otherwise. In the Galaxy, we can compare observations of diffuse NIR light and of individual stars, eliminating the need for population modeling. Moreover, we can estimate distances to stars to learn about 3D structure.

  2. (ii) Recent work by Malhotra (1994a; 1994b) has shown that the midplane of the molecular and atomic gas differs from the nominal (Galactic latitude b = 0°) plane by up to 50 pc in the inner Galaxy. Various observations (Djorgovski & Sosin 1989, Freudenreich et al 1994, Carney & Seltzer 1993) show that the stellar distribution also deviates from b = 0. We will choose fields to test the possibility that the stars behave like the gas. This constrains theories of the corrugations; e.g., if old stars participate then magnetic fields aren't the cause.

Type
Chapter 1: Are the Disk and Halo Axisymmetric?
Information
Symposium - International Astronomical Union , Volume 169: Unsolved Problems of the Milky Way , 1996 , pp. 59 - 60
Copyright
Copyright © Kluwer 1996 

References

Carney, B. W. & Seitzer, P. 1993. AJ 105, 2127.CrossRefGoogle Scholar
Djorgovski, & Sosin, 1989. ApJ Lett 341, L13.CrossRefGoogle Scholar
Elmegreen, D. M. & Elmegreen, B. G. 1984. ApJS 54, 127.CrossRefGoogle Scholar
Freudenreich, et al 1994. ApJ Lett 429, L69.CrossRefGoogle Scholar
Malhotra, S. 1994a. ApJ 433, 687.CrossRefGoogle Scholar
Malhotra, S. 1994b. ApJ , submitted.Google Scholar
Rhoads, J. E. 1995. In the proceedings of the “Formation of the Milky Way” workshop Alfaro, E., ed., Cambridge University Press.Google Scholar
Rix, H.-W. & Zaritsky, D. 1994. ApJ , submitted.Google Scholar
Wainscoat, R. J. et al 1992. ApJS 83, 111.CrossRefGoogle Scholar