St Andrews Research Repository

St Andrews University Home
View Item 
  •   St Andrews Research Repository
  • Physics & Astronomy (School of)
  • Physics & Astronomy
  • Physics & Astronomy Theses
  • View Item
  •   St Andrews Research Repository
  • Physics & Astronomy (School of)
  • Physics & Astronomy
  • Physics & Astronomy Theses
  • View Item
  •   St Andrews Research Repository
  • Physics & Astronomy (School of)
  • Physics & Astronomy
  • Physics & Astronomy Theses
  • View Item
  • Login
JavaScript is disabled for your browser. Some features of this site may not work without it.

A spectroscopic and photometric investigation of the extreme helium-rich star HD 168476

Thumbnail
View/Open
HelenWalkerPhDThesis.pdf (32.75Mb)
Date
1979
Author
Walker, H. J.
Supervisor
Hill, Philip W.
Funder
Science Research Council (Great Britain)
Metadata
Show full item record
Abstract
Spectra were obtained from several sources for a fine abundance analysis of the extreme helium-rich star HD 168476. The atmospheric parameters are found using theoretical models and abundances determined for the ions identified in the spectra. The star is found to have an effective temperature of 14000°K, log(surface gravity) of 1.5 and a microturbulent velocity of 10 km/s. Over 1400 lines are identified on the spectra ranging in wavelength from 3100A to 4925A and 5490A to 6585A, and about 530 lines are suitable for the abundance analysis. It is confirmed that helium, carbon, nitrogen and neon are overabundant, with hydrogen and oxygen underabundant. An ultraviolet spectrum of the star is also obtained and lines identified. In addition to the ions found in the visible region of the spectrum, neutral ions are also present, indicating the possibility of a cool outer shell to the star. Photometric and spectroscopic observations are made to study the light and radial velocity of the star, to determine if it is variable. Statistical tests showed that the star is variable in its V magnitude, and most probably in its colours, as well as being variable in its radial velocity. No period is found and it is suspected that the variability may be complex. Several theories for the causes of the variability are discussed and a possible origin for the extreme helium-rich nature of the star mentioned.
Type
Thesis, PhD Doctor of Philosophy
Collections
  • Physics & Astronomy Theses
URI
http://hdl.handle.net/10023/14373

Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.

Advanced Search

Browse

All of RepositoryCommunities & CollectionsBy Issue DateNamesTitlesSubjectsClassificationTypeFunderThis CollectionBy Issue DateNamesTitlesSubjectsClassificationTypeFunder

My Account

Login

Open Access

To find out how you can benefit from open access to research, see our library web pages and Open Access blog. For open access help contact: openaccess@st-andrews.ac.uk.

Accessibility

Read our Accessibility statement.

How to submit research papers

The full text of research papers can be submitted to the repository via Pure, the University's research information system. For help see our guide: How to deposit in Pure.

Electronic thesis deposit

Help with deposit.

Repository help

For repository help contact: Digital-Repository@st-andrews.ac.uk.

Give Feedback

Cookie policy

This site may use cookies. Please see Terms and Conditions.

Usage statistics

COUNTER-compliant statistics on downloads from the repository are available from the IRUS-UK Service. Contact us for information.

© University of St Andrews Library

University of St Andrews is a charity registered in Scotland, No SC013532.

  • Facebook
  • Twitter