Decade-long time-monitoring of candidate luminous blue variable stars in the two very metal-deficient star-forming galaxies DDO 68 and PHL 293B
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY(2022)
摘要
We have studied the spectral time variations of candidate luminous blue variable (cLBV) stars in two low-metallicity star-forming galaxies, DDO 68 and PHL 293B. The LBV in DDO 68, located in H ii region #3, shows an outburst, with an increase of more than 1000 times in H alpha luminosity during the period 2008-2010. The broad emission of the H i and He i lines display a P Cygni profile, with a relatively constant terminal velocity of similar to 800 km s(-1), reaching a maximum luminosity L(H alpha) of similar to 2 x 10(38) erg s(-1), with a full width at half-maximum (FWHM) of similar to 1000-1200 km s(-1). On the other hand, since the discovery of a cLBV in 2001 in PHL 293B, the fluxes of the broad components and the broad-to-narrow flux ratios of the H i and He i emission lines in this galaxy have remained nearly constant over 16 yr, with small variations. The luminosity of the broad H alpha component varies between similar to 2 x 10(38) erg s(-1) and similar to 10(39) erg s(-1), with the FWHM varying in the range similar to 500-1500 km s(-1). Unusually persistent P Cygni features are clearly visible until the end of 2020 despite a decrease of the broad-to-narrow flux ratio in the most recent years. A terminal velocity of similar to 800 km s(-1) is measured from the P Cygni profile, similar to the one in DDO 68, although the latter is 3.7 more metal-deficient than PHL 293B. The relative constancy of the broad H alpha luminosity in PHL 293B suggests that it is due to a long-lived stellar transient of type LBV/SN IIn.
更多查看译文
关键词
galaxies: abundances, galaxies: dwarf, galaxies: ISM, galaxies: starburst
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要