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On the oscillation spectra of ultra compact stars: an extensive survey of gravitational-wave modes

On the oscillation spectra of ultra compact stars: an extensive survey of gravitational-wave modes
On the oscillation spectra of ultra compact stars: an extensive survey of gravitational-wave modes
An extensive survey of gravitational-wave modes for uniform density stars is presented. The study covers stars ranging in compactness from R/M=100 to the limit of stability in general relativity: R/M = 9/4. We establish that polar and axial gravitational-wave modes exist for all these stellar models. Moreover, there are two distinct families of both axial and polar modes. We discuss the physics of these modes and argue that one family is primarily associated with the interior of the star, while the second family is mainly associated with the stellar surface. We also show that the problem of axial perturbations has all the essential features of the polar problem as far as gravitational waves are concerned. This means that the axial problem is much more important than has previously been assumed. We also find some surprising features, such as avoided crossings between the polar gravitational-wave modes and the Kelvin f-mode as the star becomes very compact. This seems to suggest that the f-mode should be considered on equal footing with the polar w-modes for ultracompact stars. All modes may have the main character of trapped modes inside the curvature potential barrier for R/M < 3.
0004-637X
855-864
Andersson, Nils
2dd6d1ee-cefd-478a-b1ac-e6feedafe304
Kojima, Yasufuni
420d9412-61c6-4bc0-939f-2519de9a2863
Kokkotas, Kostas D.
0b8bb98a-a65f-434b-855b-ec5b488b4a96
Andersson, Nils
2dd6d1ee-cefd-478a-b1ac-e6feedafe304
Kojima, Yasufuni
420d9412-61c6-4bc0-939f-2519de9a2863
Kokkotas, Kostas D.
0b8bb98a-a65f-434b-855b-ec5b488b4a96

Andersson, Nils, Kojima, Yasufuni and Kokkotas, Kostas D. (1996) On the oscillation spectra of ultra compact stars: an extensive survey of gravitational-wave modes. The Astrophysical Journal, 462, 855-864.

Record type: Article

Abstract

An extensive survey of gravitational-wave modes for uniform density stars is presented. The study covers stars ranging in compactness from R/M=100 to the limit of stability in general relativity: R/M = 9/4. We establish that polar and axial gravitational-wave modes exist for all these stellar models. Moreover, there are two distinct families of both axial and polar modes. We discuss the physics of these modes and argue that one family is primarily associated with the interior of the star, while the second family is mainly associated with the stellar surface. We also show that the problem of axial perturbations has all the essential features of the polar problem as far as gravitational waves are concerned. This means that the axial problem is much more important than has previously been assumed. We also find some surprising features, such as avoided crossings between the polar gravitational-wave modes and the Kelvin f-mode as the star becomes very compact. This seems to suggest that the f-mode should be considered on equal footing with the polar w-modes for ultracompact stars. All modes may have the main character of trapped modes inside the curvature potential barrier for R/M < 3.

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Published date: 1996

Identifiers

Local EPrints ID: 29418
URI: http://eprints.soton.ac.uk/id/eprint/29418
ISSN: 0004-637X
PURE UUID: 2d0851a0-bf14-47f5-a53d-50a6b8ce8f42
ORCID for Nils Andersson: ORCID iD orcid.org/0000-0001-8550-3843

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Date deposited: 08 Feb 2007
Last modified: 08 Jan 2022 02:48

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Contributors

Author: Nils Andersson ORCID iD
Author: Yasufuni Kojima
Author: Kostas D. Kokkotas

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