Pulsations and long-term photometric variability of three candidates for protoplanetary nebulae

Архипова, В. П.; Иконникова, Н. П.; Комиссарова, Г. В.

doi:10.1134/s1063773710040055

Cited by 29 publications

(47 citation statements)

References 18 publications

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“…c Percy & Welch (1981), where the data are listed. d Arkhipova et al (1993Arkhipova et al ( , 2000Arkhipova et al ( , 2010; data available on-line from VizieR We combined with our V observations the long and consistent data set of Fernie's. In comparing the data of Fernie's with ours during the overlap from 1984 to 1998, we find that there are 22 dates on which we observed on the same night, and from these we find an average offest of 0.000 ± 0.002.…”

Section: Combined Light Curvesmentioning

confidence: 99%

“…Combined Light Curves IRAS 18095+2704 was observed by Arkhipova et al (1993Arkhipova et al ( , 2000Arkhipova et al ( , 2010 for 19 years, beginning with only a few observations in 1990-1992 but then more frequently through 2008. They quote an uncertainty of ±0.01 mag in B andV.…”

Section: Iras 18095+2704mentioning

confidence: 99%

“…Subsequent long-term photometric monitoring has revealed periods for many of them, ranging from 35 to 160 days (Arkhipova et al 2000(Arkhipova et al , 2010(Arkhipova et al , 2011Hrivnak et al 2010). When combined with stellar pulsation models (e.g., Fokin et al 2001), pulsation periods and amplitudes have the potential of yielding information on the mass, luminosity, and stellar structure of these transitional objects.…”

Section: Introductionmentioning

confidence: 99%

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Variability in Proto-Planetary Nebulae. Iv. Light Curve Analysis of Four Oxygen-Rich, F Spectral Type Objects

Hrivnak¹,

Lu²,

Nault³

2015

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We present new light curves covering 14-19 years of observations of four bright proto-planetary nebulae (PPNs), all oxygen-rich and of F spectral type. They each display cyclical light curves with significant variations in amplitude. All four were previously known to vary in light. Our data were combined with published data and searched for periodicity. The results are as follows: IRAS 19475+3119 (HD 331319; 41.0 days), 17436+5003 (HD 161796; 45.2 days), 19386+0155 (101.8 days), and 18095+2704 (113.3 days). The two longer periods are in agreement with previous studies while the two shorter periods each reveal for the first time a dominant period over these long observing intervals. Multiple periods were also found for each object. The secondary periods were all close to the dominant periods, with P 2 /P 1 ranging from 0.86 to 1.06. The variations in color reveal maximum variations in T eff of 400-770 K. These variations are due to pulsations in these post-asymptotic giant branch objects. Maximum seasonal light variations are all less than 0.23 mag (V), consistent for their temperatures and periods with the results of Hrivnak et al. for 12 C-rich PPNs. For all of these PPNs, there is an inverse relationship between period and temperature; however, there is a suggestion that the period-temperature relationship may be somewhat steeper for the O-rich than for the C-rich PPNs.

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Section: Combined Light Curvesmentioning

confidence: 99%

Section: Iras 18095+2704mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Variability in Proto-Planetary Nebulae. Iv. Light Curve Analysis of Four Oxygen-Rich, F Spectral Type Objects

Hrivnak¹,

Lu²,

Nault³

2015

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“…The type of variability depends on the star's effective temperature, i.e., on its position on the horizontal evolutionary track. In particular, F-G supergiants with infrared excesses exhibit semiregular brightness variations with time scales from 40 to 130 days caused by their pulsational instability (Hrivnak and Lu 2000;Kiss et al 2007;Arkhipova et al 2010;Hrivnak et al 2010). Hotter stars, early B supergiants with infrared excesses, exhibit photometric variability without any distinct periodicity with amplitudes from 0 m .2 to 0 m .4 in the V band on time scales from one day to several days (Hrivnak and Lu 2000) and a color-magnitude relation that cannot be explained by temperature variations.…”

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confidence: 99%

Variability and possible rapid evolution of the hot post-AGB stars Hen 3-1347, Hen 3-1428, and LSS 4634

Архипова¹,

Бурлак²,

Есипов³

et al. 2014

Astron. Lett.

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We present the results of spectroscopic and photometric observations for three hot southernhemisphere post-AGB objects, Hen 3-1347 = IRAS 17074-1845, Hen 3-1428 = IRAS 17311-4924, and LSS 4634 = IRAS 18023-3409. In the spectrograms taken with the 1.9-m telescope of the South African Astronomical Observatory (SAAO) in 2012, we have measured the equivalent widths of the most prominent spectral lines. Comparison of the new data with those published previously points to a change in the spectra of Hen 3-1428 and LSS 4634 in the last 20 years. Based on ASAS data, we have detected rapid photometric variability in all three stars with an amplitude up to 0.3 mag, 0.4 mag in the V band. A similarity between the patterns of variability for the sample stars and other hot protoplanetary nebulae is pointed out. We present the results of U BV observations for Hen 3-1347, according to which the star undergoes rapid irregular brightness variations with maximum amplitudes ∆V =0.25 mag, ∆B=0.25 mag, and ∆U =0.30 mag and shows color-magnitude correlations. Based on archival data, we have traced the photometric history of the stars over more than 100 years. Hen 3-1347 and LSS 4634 have exhibited a significant fading on a long time scale. The revealed brightness and spectrum variations in the stars, along with evidence for their enhanced mass, may be indicative of their rapid post-AGB evolution.Keywords: post-AGB stars, planetary nebulae, photometric and spectroscopic observations, photometric variability. * E-mail: ikonnikova@gmail.com 2 INTRODUCTIONThe post-asymptotic giant branch (post-AGB) phase of evolution of intermediate-mass stars (M ZAMS = 0.8 − 8M ⊙ ) is the transition period from the asymptotic giant branch (AGB) to planetary nebula nuclei.Protoplanetary nebulae are stars of spectral types from late G to early B with extended atmospheres surrounded by dust envelopes formed through intense mass loss at previous evolutionary phases. The dust envelopes gradually dissipate, which is reflected in the visibility of the stars at optical wavelengths.The studies of post-AGB stars were begun in the mid-1980s after the appearance of the IRAS survey. These objects were initially suspected and subsequently revealed among the supergiant stars with dust envelopes detected in this survey (Parthasarathy and Pottasch 1986;van der Veen et al. 1989;Hrivnak et al. 1989).An important feature of post-AGB stars is their photometric variability. The type of variability depends on the star's effective temperature, i.e., on its position on the horizontal evolutionary track. In particular, F-G supergiants with infrared excesses exhibit semiregular brightness variations with time scales from 40 to 130 days caused by their pulsational instability (Hrivnak and Lu 2000;Kiss et al. 2007;Arkhipova et al. 2010;Hrivnak et al. 2010). Hotter stars, early B supergiants with infrared excesses, exhibit photometric variability without any distinct periodicity with amplitudes from 0 m .2 to 0 m .4 in the V band on time scales from one day to several days (Hrivnak a...

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“…Figure 15 shows the period-temperature relation for 12 carbon-rich objects from Hrivnak et al (2010) and for four oxygen-rich stars: V887 Her, V1648 Aql, HD 331319, and V1027 Cyg. The pulsation periods for V887 Her, V1648 Aql, and HD 331319 were taken from Arkhipova et al (2010Arkhipova et al ( , 2006, while the effective temperatures for V887 Her and V1648 Aql were estimated by Klochkova (1995) and Pereira et al (2004), respectively. Two effective temperature determinations exist for HD 331319: 7750 ± 100 K (Arellano Ferro et al 2001) and 7200 ± 100 (Klochkova et al 2002).…”

Section: Discussionmentioning

confidence: 99%

Photometric and spectroscopic study of the supergiant with an infrared excess V1027 Cygni

et al. 2016

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We present the results of our U BV and JHKLM -photometry for the semiregular pulsating variable V1027 Cyg, a supergiant with an infrared excess, over the period from 1997 to 2015 (U BV ) and in . Together with the new data, we analyze the photometric observations of V1027 Cyg that we have obtained and published previously. Our search for a periodicity in the U BV brightness variations has led to several periods from P = 212 10. An ambiguous correlation of the B − V and U − B colors with the brightness has been revealed. For example, a noticeable bluing of the star was observed during the deep 1992, 2008, and 2011 minima, while the variations with smaller amplitudes show an increase in B − V at the photometric minima. The spectral energy distribution for V1027 Cyg from our photometry in the range 0.36 (U )-5.0 (M ) µm corresponds to spectral types from G8I to K3I at different phases of the pulsation cycle. Low-resolution spectra of V1027 Cyg in the range λ4400-9200 A were taken during 16 nights over the period . At the 1995 and 2011 photometric minima the star's spectrum exhibited molecular TiO bands whose intensity corresponded to spectral types M0-M1, while the photometric data point to a considerably earlier spectral type. We hypothesize that the TiO bands are formed in the upper layers of the extended stellar atmosphere. We have measured the equivalent widths of the strongest absorption lines, in particular, the infrared Ca II triplet in the spectrum of V1027 Cyg. The calcium triplet (Ca T) with W λ (Ca T) = 20.3 ± 1.8Å as a luminosity indicator for supergiants places V1027 Cyg in the region of the brightest G-K supergiants. V1027 Cyg has been identified with the infrared source IRAS 20004+2955 and is currently believed to be a candidate for post-AGB stars. The evolutionary status of the star and its difference from other post-AGB objects are discussed.

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Pulsations and long-term photometric variability of three candidates for protoplanetary nebulae

Cited by 29 publications

References 18 publications

Variability in Proto-Planetary Nebulae. Iv. Light Curve Analysis of Four Oxygen-Rich, F Spectral Type Objects

Variability in Proto-Planetary Nebulae. Iv. Light Curve Analysis of Four Oxygen-Rich, F Spectral Type Objects

Variability and possible rapid evolution of the hot post-AGB stars Hen 3-1347, Hen 3-1428, and LSS 4634

Photometric and spectroscopic study of the supergiant with an infrared excess V1027 Cygni

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