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J/A+A/336/263       Radial velocities of HR 4049 (Bakker+ 1998)

Spectral variability of the binary HR 4049 Bakker E.J., Lambert D.L., Van Winckel H., McCarthy J.K., Waelkens C., Gonzalez G. <Astron. Astrophys. 336, 263 (1998)> =1998A&A...336..263B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Line Profiles ; Radial velocities Keywords: line formation - line profiles - AGB and post-AGB stars - close binaries - stars: emission line, Be - individual stars: HR 4049 Abstract: The C I, Na I D, and Hα lines of the post-AGB binary HR 4049 have been studied. Na I D variability results from a photospheric absorption component ([Na/H]=-1.6±0.2) which follows the velocity of the primary and a stationary, non-photospheric component. An emission component is attributed to the circumbinary disc, and an absorption component to mass-loss from the system with a velocity of 5.3±0.5km/s. The Hα profile varies with the orbital period. The two strong shell type emission peaks are identified as from one single broad emission feature with an absorption centered around -7.5km/s. The intensity variations are largely attributed to a differential amount of reddening towards the Hα emitting region and the stellar continuum. The radial velocities suggest that the Hα emission moves in phase with the primary, but with a slightly lower velocity amplitude. From this we infer that the Hα emission comes from outside the orbit of the primary, but still gravitationally bound to the primary. Hα also shows a weak emission feature at -21.3±3.5km/s, which originates from the circumbinary disc and a weak absorption feature at -7.5±1.6km/s due to absorption by the circumbinary disc. We propose two competing models that could account for the observed velocity and intensity variations of the Hα profile. Model I: light from the primary reflects on a localized spot near the inner radius of the circumbinary disc which is closest to the primary. Model II: Hα emission originates in the outer layers of the extended atmosphere of the primary due to activity. These activities are locked to the position of the primary in its orbit. We discuss the similarities of variability and shape of the Hα emission of HR 4049 with those of early type T-Tauri stars (e.g SU Aur). Objects: ---------------------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------------------- 10 18 07.6 -28 59 32 HR 4049 = HD 89353 ---------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3.dat 49 32 Log of 32 Na I D observations table4.dat 49 60 Log of 60 Hα observations tables.tex 109 132 LaTeX version of the tables fig12.ps 76 1675 *Observed NaI D2 line profiles in order of relative orbital phase φrel fig13.ps 76 2386 Figure 12 continued fig14.ps 76 2297 *Observed Hα line profiles in order of relative orbital phase φrel fig15.ps 76 2301 Figure 14 continued fig16.ps 76 2309 Figure 14 continued fig17.ps 76 2036 Figure 14 continued
Note on fig12.ps: The systemic velocity of the binary, γs=-32.15km/s, is at zero (solid line) with on both sides a short-dashed line at the extreme velocity of the star in its orbit. The long-dashed lines correspond to the velocity of that star. The measured velocities and intensities of the marker points are marked. The photospheric component (on the profile, only if measured) and the predicted stellar velocity (at an intensity of 1.0) have both been plotted with a dot. These two points can be at different velocities because the photospheric velocity cannot be very well determined from the observed NaI D2 profile. The circumsystem markers (diamond and triangle) and the interstellar markers (crosses) have been marked. In each window, the upper left corner gives the absolute orbital phase and the upper right corner the telescope/instrument with which the spectrum was obtained. Note on fig14.ps: The systemic velocity of the binary, γs=-32.15km/s, is at zero (solid line) with on both sides a short-dashed line at the extreme velocity of the star in its orbit. The long-dashed lines correspond to the velocity of that star. The "blue maximum" (cross), "blue minimum" (open square), "central maximum" (open triangle), "red minimum" (open diamond), and "red maximum" (asterisk) have been marked. In each window, the upper left corner gives the absolute orbital phase and the upper right corner the telescope/instrument with which the spectrum was obtained.
See also: J/A+A/306/924 : Optical spectrum of HR 4049 (Bakker+, 1996), Paper I. Byte-by-byte Description of file: table3.dat table4.dat
Bytes Format Units Label Explanations
1- 8 A8 "DD/MM/YY" Date Observation date 10- 20 F11.3 d HJD Heliocentric Julian date 22- 25 F4.2 --- φabs Phase (1) 27- 35 A9 --- Tel/Instr Telescope/Instrument (2) 37- 42 I6 --- R Spectral resolving power 44- 49 F6.2 km/s HRV Heliocentric radial velocity (3)
Note (1): φabs=0.0 at HJD=T0=2446746.6±2.4 Note (2): CAT/CES: Twenty-three Hα and two Na I D single-order spectra (R∼55,000) have been obtained by HvW and CW on the ESO observatory at La Silla (Chili) using the coude echelle spectrograph at the 1.4m Coude Auxiliary Telescope. McD/CS11: Twenty-three Hα and twenty-one Na I D single-order spectra (R∼60,000) have been obtained by DLL, JKM, and Jos Tomkin using the echelle spectrograph (6-foot camera) on the 2.7m McDonald telescope. McD/CE: Ten multi-order spectra (R∼45,000) have been obtained by GG using the Sandiford cassegrain echelle spectrograph (McCarthy et al., 1993PASP..105..881M) on the 2.1m McDonald telescope. Eight contain Hα and four Na I D. WHT/UES: Three multi-order spectra (R∼50,000) have been obtained in service time using the Utrecht echelle spectrograph on the 4.2m William Herschel telescope on La Palma (Unger, 1994, La Palma Technical Notes No. XXIII). All three spectra contain Hα, Na I D, and numerous photospheric absorption lines. An extensive analysis of these spectra and complete line identification have been published in Paper I (Bakker et al., 1996, Cat. J/A+A/306/924). McD/CS21: Two multi-order spectra (R∼160,000) have been obtained by EJB using the cross-dispersed echelle spectrograph (Tull et al., 1995PASP..107..251T) at the 2.7m McDonald telescope. Both contain Hα and Na I D. CTIO/ES: One single-order Hα spectrum (R∼18,000) has been obtained by Andy McWilliam using the echelle spectrograph with the air Schmidt camera on the 4m CTIO telescope. Note (3): In table3.dat, heliocentric radial velocities are computed using the orbital parameters In table4.dat, heliocentric radial velocities are measured from CI, N I, and O I lines; the velocity accuracy is 2km/s
Acknowledgements: Eric J. Bakker
(End) Patricia Bauer [CDS] 05-Mar-1998
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