Structure and spectra of irradiated secondaries in close binaries

Wawrzyn, A. C.; Barman, Travis; Günther, H. M.; Hauschildt, P. H.; Exter, Katrina

doi:10.1051/0004-6361/200911789

Cited by 18 publications

(21 citation statements)

References 44 publications

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“…a (Kurucz 1979) subgiant. However the day-side temperature in irradiated models can reach factors of between four and ten times larger than the shadowed side (e.g., Wawrzyn et al 2009).…”

Section: Discussionmentioning

confidence: 99%

Pan-Chromatic Observations of the Remarkable Nova Large Magellanic Cloud 2012

Schwarz

Shore

Page

et al. 2015

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We present the results of an intensive multiwavelength campaign on nova LMC 2012. This nova evolved very rapidly in all observed wavelengths. The time to fall two magnitudes in the V band was only 2 days. In X-rays the super soft phase began 13 ± 5 days after discovery and ended around day 50 after discovery. During the super soft phase, the Swift/XRT and Chandra spectra were consistent with the underlying white dwarf (WD) being very hot, ∼1 MK, and luminous, ∼10 38 erg s −1 . The UV, optical, and near-IR photometry showed a periodic variation after the initial and rapid fading had ended. Timing analysis revealed a consistent 19.24 ± 0.03 hr period in all UV, optical, and near-IR bands with amplitudes of ∼0.3 mag which we associate with the orbital period of the central binary. No periods were detected in the corresponding X-ray data sets. A moderately high inclination system, i = 60 ± 10, was inferred from the early optical emission lines. The HST/STIS UV spectra were highly unusual with only the N V (1240 Å) line present and superposed on a blue continuum. The lack of emission lines and the observed UV and optical continua from four epochs can be fit with a low mass ejection event, ∼10 −6  M , from a hot and massive WD near the Chandrasekhar limit. The WD, in turn, significantly illuminated its subgiant companion which provided the bulk of the observed UV/optical continuum emission at the later dates. The inferred extreme WD characteristics and low mass ejection event favor nova LMC 2012 being a recurrent nova of the U Sco subclass.

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“…a (Kurucz 1979) subgiant. However the day-side temperature in irradiated models can reach factors of between four and ten times larger than the shadowed side (e.g., Wawrzyn et al 2009).…”

Section: Discussionmentioning

confidence: 99%

Pan-Chromatic Observations of the Remarkable Nova Large Magellanic Cloud 2012

Schwarz

Shore

Page

et al. 2015

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“…To model the effects of irradiation and reproduce both the spectral variations and the reflection effect in the light curve of AA Dor, we followed the description of the geometry of eclipsing binaries developed by Günther & Wawrzyn (2011) and Wawrzyn et al (2009) (2011), we adopted the same spherical coordinate system with the origin at the centre of the secondary star and the z-axis intersecting the centre of the primary. The z-axis intersects the surface of the companion at the substellar point, where irradiation is the strongest.…”

Section: Modelling the Spectrum Of The Irradiated Secondarymentioning

confidence: 99%

Looking on the bright side: The story of AA Doradus as revealed by its cool companion

Vučković

Østensen

Németh

et al. 2016

A&A

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The effects of irradiation on the secondary stars of close binary systems are crucial for reliably determining the system parameters and for understanding the close binary evolution. They affect the stellar structure of the irradiated star and are reflected in the appearance of characteristic features in the spectroscopic and photometric data of these systems. We aim to study the light that originates from the irradiated side of the low-mass component of a close binary eclipsing system, which comprises a hot subdwarf primary and a low mass companion, to precisely interpret their high precision photometric and spectroscopic data, and accurately determine their system and surface parameters. We reanalyse the archival high-resolution time-resolved VLT/UVES spectra of AA Dor system, where irradiation features have already been detected. After removing the predominant contribution of the hot subdwarf primary, the residual spectra reveal more than 100 emission lines from the heated side of the secondary, which show maximum intensity close to the phases around the secondary eclipse. We analyse the residual spectrum to model the irradiation of the low-mass secondary. We perform a detailed analysis of 22 narrow emission lines of the irradiated secondary, mainly of O ii, with a few significant C ii lines. Their phase profiles constrain the emission region of the heated side to a radius ≥95% of the radius of the secondary, while the shape of their velocity profiles reveals two distinct asymmetry features, one at the quadrature and the other at the secondary eclipse. In addition, we identify weaker emission signatures originating from more than 70 lines, including lines from He i, N ii, Si iii, Ca ii, and Mg ii. From the emission lines of the heated side of the secondary star, we determine the radial velocity semi-amplitude of the centre-of-light and correct it to the centre-of-mass of the secondary which, in turn, gives accurate masses of both components of the AA Dor system. The resulting masses M 1 = 0.46 ± 0.01 M and M 2 = 0.079 ± 0.002 M are in perfect accordance with those of a canonical hot subdwarf primary and a low mass that is just at the substellar limit for the companion. We also compute a first generation atmosphere model of the low mass secondary, which includes irradiation effects and matches the observed spectrum well. We find an indication of an extended atmosphere of the irradiated secondary star.

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“…2.3). Wawrzyn et al (2009) suggested the enriched C and N abundance required to reproduce the strong lines may be the result of polluted material accreted from the primary. NGC 6326 is also one of a few post-CE binaries showing the higher ionisation C IV lines (Pollacco & Bell 1994;Corradi et al 2011;Miszalski et al 2011b).…”

Section: Gemini South Gmos Spectroscopy Of Ngc 6326mentioning

confidence: 99%

Discovery of close binary central stars in the planetary nebulae NGC 6326 and NGC 6778

Miszalski

Jones

Rodríguez‐Gil

et al. 2011

A&A

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We present observations proving the close binary nature of the central stars belonging to the planetary nebulae (PNe) NGC 6326 and NGC 6778. Photometric monitoring reveals irradiated lightcurves with orbital periods of 0.372 and 0.1534 days, respectively, constituting firm evidence that they passed through a common-envelope (CE) phase. Unlike most surveys for close binary central stars (CSPN) however, the binary nature of NGC 6326 was first revealed spectroscopically and only later did photometry obtain an orbital period. Gemini South observations revealed a large 160 km s −1 shift between the nebula and emission lines of C III and N III well known to originate from irradiated atmospheres of main-sequence companions. These so-called weak emission lines are fairly common in PNe and measurement of their radial velocity shifts in spectroscopic surveys could facilitate the construction of a statistically significant sample of post-CE nebulae. There is growing evidence that this process can be further accelerated by preselecting nebulae with traits of known post-CE nebulae. Both NGC 6326 and NGC 6778 were selected for their rich attribution of low-ionisation filaments and collimated outflows, thereby strengthening the connection between these traits and post-CE CSPN.

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Structure and spectra of irradiated secondaries in close binaries

Cited by 18 publications

References 44 publications

Pan-Chromatic Observations of the Remarkable Nova Large Magellanic Cloud 2012

Pan-Chromatic Observations of the Remarkable Nova Large Magellanic Cloud 2012

Looking on the bright side: The story of AA Doradus as revealed by its cool companion

Discovery of close binary central stars in the planetary nebulae NGC 6326 and NGC 6778

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