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Title: Episodic mass loss from the hydrogen-deficient central star of the planetary nebula Longmore 4

Abstract

A spectacular transient mass-loss episode from the extremely hot, hydrogen-deficient central star of the planetary nebula (PN) Longmore 4 (Lo 4) was discovered in 1992 by Werner et al. During that event, the star temporarily changed from its normal PG 1159 spectrum to that of an emission-line low-luminosity early-type Wolf-Rayet [WCE] star. After a few days, Lo 4 reverted to its normal, predominantly absorption-line PG 1159 type. To determine whether such events recur, and if so how often, I monitored the optical spectrum of Lo 4 from early 2003 to early 2012. Out of 81 spectra taken at random dates, 4 of them revealed mass-loss outbursts similar to that seen in 1992. This indicates that the episodes recur approximately every 100 days (if the recurrence rate has been approximately constant and the duration of a typical episode is ∼5 days), and that the star is in a high-mass-loss state about 5% of the time. Since the enhanced stellar wind is hydrogen-deficient, it arises from the photosphere and is unlikely to be related to phenomena such as a binary or planetary companion or infalling dust. I speculate on plausible mechanisms for these unique outbursts, including the possibility that they are relatedmore » to the non-radial GW Vir-type pulsations exhibited by Lo 4. The central star of the PN NGC 246 has stellar parameters similar to those of Lo 4, and it is also a GW Vir-type pulsator with similar pulsation periods. I obtained 167 spectra of NGC 246 between 2003 and 2011, but no mass ejections were found.« less

Authors:
 [1]
  1. Current address: Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802, USA. (United States)
Publication Date:
OSTI Identifier:
22342275
Resource Type:
Journal Article
Journal Name:
Astronomical Journal (New York, N.Y. Online)
Additional Journal Information:
Journal Volume: 148; Journal Issue: 3; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1538-3881
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; APPROXIMATIONS; DUSTS; EMISSION; HYDROGEN; LUMINOSITY; MASS TRANSFER; PHOTOSPHERE; PLANETARY NEBULAE; PULSATIONS; RANDOMNESS; SPECTRA; STARS; STELLAR WINDS; TRANSIENTS; WOLF-RAYET STARS

Citation Formats

Bond, Howard E., E-mail: heb11@psu.edu. Episodic mass loss from the hydrogen-deficient central star of the planetary nebula Longmore 4. United States: N. p., 2014. Web. doi:10.1088/0004-6256/148/3/44.
Bond, Howard E., E-mail: heb11@psu.edu. Episodic mass loss from the hydrogen-deficient central star of the planetary nebula Longmore 4. United States. https://doi.org/10.1088/0004-6256/148/3/44
Bond, Howard E., E-mail: heb11@psu.edu. 2014. "Episodic mass loss from the hydrogen-deficient central star of the planetary nebula Longmore 4". United States. https://doi.org/10.1088/0004-6256/148/3/44.
@article{osti_22342275,
title = {Episodic mass loss from the hydrogen-deficient central star of the planetary nebula Longmore 4},
author = {Bond, Howard E., E-mail: heb11@psu.edu},
abstractNote = {A spectacular transient mass-loss episode from the extremely hot, hydrogen-deficient central star of the planetary nebula (PN) Longmore 4 (Lo 4) was discovered in 1992 by Werner et al. During that event, the star temporarily changed from its normal PG 1159 spectrum to that of an emission-line low-luminosity early-type Wolf-Rayet [WCE] star. After a few days, Lo 4 reverted to its normal, predominantly absorption-line PG 1159 type. To determine whether such events recur, and if so how often, I monitored the optical spectrum of Lo 4 from early 2003 to early 2012. Out of 81 spectra taken at random dates, 4 of them revealed mass-loss outbursts similar to that seen in 1992. This indicates that the episodes recur approximately every 100 days (if the recurrence rate has been approximately constant and the duration of a typical episode is ∼5 days), and that the star is in a high-mass-loss state about 5% of the time. Since the enhanced stellar wind is hydrogen-deficient, it arises from the photosphere and is unlikely to be related to phenomena such as a binary or planetary companion or infalling dust. I speculate on plausible mechanisms for these unique outbursts, including the possibility that they are related to the non-radial GW Vir-type pulsations exhibited by Lo 4. The central star of the PN NGC 246 has stellar parameters similar to those of Lo 4, and it is also a GW Vir-type pulsator with similar pulsation periods. I obtained 167 spectra of NGC 246 between 2003 and 2011, but no mass ejections were found.},
doi = {10.1088/0004-6256/148/3/44},
url = {https://www.osti.gov/biblio/22342275}, journal = {Astronomical Journal (New York, N.Y. Online)},
issn = {1538-3881},
number = 3,
volume = 148,
place = {United States},
year = {Mon Sep 01 00:00:00 EDT 2014},
month = {Mon Sep 01 00:00:00 EDT 2014}
}