Philippe Eenens | Universidad de Guanajuato (original) (raw)
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Papers by Philippe Eenens
![Research paper thumbnail of Near-Infrared Spectra of LBV; Be and B[e] Stars: Does Axisymmetry Provide a Morphological Link?](https://attachments.academia-assets.com/54171945/thumbnails/1.jpg)
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Photometric time series in different narrow-band filters are given for the eclipsing binary syste... more Photometric time series in different narrow-band filters are given for the eclipsing binary systems Cyg OB2 #5 = V729 Cyg = BD+40 4220. The data were obtained with the CCD camera at the 1.2m telescope at the Observatoire de Haute Provence. (1 data file).
We discuss the first results of our ongoing optical spectroscopic monitoring campaign of the two ... more We discuss the first results of our ongoing optical spectroscopic monitoring campaign of the two O-type stars 9 Sgr and HD 168112. Both objects display a non-thermal radio emission and were considered as single stars. Based on a large set of high-resolution spectra, we find that 9 Sgr is clearly an eccentric SB2 binary with an orbital period of several years. On the other hand, no evidence for radial velocity variations attributable to binary motion is found in our spectra of HD 168112.
Aims. We present the results obtained from a long-term spectroscopic campaign devoted to the mult... more Aims. We present the results obtained from a long-term spectroscopic campaign devoted to the multiplicity of O-type stars in the young open cluster NGC2244 and in the Mon OB2 association. Methods. Our spectroscopic monitoring was performed over several years, allowing us to probe different time-scales. For each star, several spectral diagnostic tools are applied, in order to search for line shifts and profile variations. We also measure the projected rotational velocity and revisit the spectral classification. Results. In our sample, several stars were previously considered as spectroscopic binaries, though only a few scattered observations were available. Our results now reveal a more complex situation. Our study identifies two new spectroscopic binaries (HD46149 in NGC2244 and HD46573 in MonOB2). The first object is a long-period double-lined spectroscopic binary, though the exact value of its period remains uncertain and the second object is classified as an SB1 system with a period of about 10.67 days but the time series of our observations do not enable us to derive a unique orbital solution for this system. We also classify another star as variable in radial velocity (HD46150) and we detect line profile variations in two rapid rotators (HD46056 and HD46485). Conclusions. This spectroscopic investigation places a firm lower limit (17%) on the binary fraction of O-stars in NGC2244 and reveals the lack of short-period O+OB systems in this cluster. In addition, a comparison of these new results with two other well-studied clusters (NGC6231 and IC1805) puts forward possible hints of a relation between stellar density and binarity, which could provide constraints on the theories about the formation and early evolution of hot stars.
We reported in 2008 the first detection of the binary nature of Cyg OB2 #9. Since then, we have c... more We reported in 2008 the first detection of the binary nature of Cyg OB2 #9. Since then, we have continued our spectroscopic monitoring of this object, doubling the number of available spectra of the star while covering a second periastron passage. Using a variety of techniques, the radial velocities were estimated and a first, preliminary orbital solution was derived (P=2.4 yrs). The mass ratio appears close to unity and the eccentricity is large, 0.7-0.75.
The line profile variability and photometric variability of the O9.5 Vp star HD93521 are examined... more The line profile variability and photometric variability of the O9.5 Vp star HD93521 are examined in order to establish the properties of the non-radial pulsations in this star. Fourier techniques are used to characterize the modulations of the He I 5876, 6678 and H-alpha lines in several spectroscopic time series and to search for variations in a photometric time series. Our spectroscopic data confirm the existence of two periods of 1.75 and 2.89 hr. The line profiles, especially those affected by emission wings, exhibit also modulations on longer time scales, but these are epoch-dependent and change from line to line. Unlike previous claims, we find no unambiguous signature of the rotational period in our data, nor of a third pulsation period (corresponding to a frequency of 2.66 day$^{-1}$). HD 93521 very likely exhibits non-radial pulsations with periods of 1.75 and 2.89 hr with lsimeq8pm1l \simeq 8 \pm 1lsimeq8pm1 and lsimeq4pm1l \simeq 4 \pm 1lsimeq4pm1 respectively. No significant signal is found in the first harmonics of these two periods. The 2.89 hr mode is seen at all epochs and in all lines investigated, while the visibility of the 1.75 hr mode is clearly epoch dependent. Whilst light variations are detected, their connection to these periodicities is not straightforward.
Proceedings of The International Astronomical Union, 2007
After realising that V2368 Oph is a variable star, we started systematic UBV observations of it a... more After realising that V2368 Oph is a variable star, we started systematic UBV observations of it at Hvar and SPM observatories. A limited set of UBV observations was also obtained by HA at the Turkish National Observatory. Simultaneously with photometric observations, we also begun to collect electronic spectra in Ondrejov, San Pedro Martir, and Dominion Astrophysical Observatory. (6 data files).
After a serendipitious discovery that HD 143418 is a light variable, we analyzed numerous UBV obs... more After a serendipitious discovery that HD 143418 is a light variable, we analyzed numerous UBV observations and Hipparcos Hp magnitudes transformed to Johnson V to find out whether the object is a very unusual spectroscopic binary. Initial reductions of new photometry were carried out with the HEC22 program, while the new spectra were reduced in the IRAF and SPEFO programs. Orbital elements were derived with the FOTEL program, the KOREL disentangling was applied, and period searches were carried out using phase dispersion minimalization technique and the program PERIOD04. Final modeling of radial-velocity and light variations was carried out in PHOEBE. (1 data file).
An analysis of new spectroscopic and photoelectric UBV observations, satisfactorily covering the ... more An analysis of new spectroscopic and photoelectric UBV observations, satisfactorily covering the whole orbital period of V436 Per, together with existing data allowed us to improve the knowledge of the basic physical characteristics of the binary and its components. In several aspects, our new results differ from the findings of Paper I (Harmanec et al., 1997, Cat. <J/A+A/319/867>) of this series: In particular, we found that it is the star eclipsed in the secondary minimum which is slightly more massive and larger than the optical primary. We also conclude that the apsidal advance -- if present at all -- is much slower than that estimated in a previous study. The orbital period might be increasing by 0.28 s per year but also this finding is very uncertain and needs verification by future observations. It is encouraging to note that two completely independent sets of programs for light-curve solutions lead to identical results. A notable finding is that both binary components rotate with very similar -- if not identical -- rotational periods of 1.45d and 1.40d, much shorter than what would correspond to a 10.9d spin-orbit synchronization period at periastron. Rapid line-profile changes reported earlier could not be confirmed from new, dedicated series of high-resolution and S/N spectra. (2 data files).
Astronomy & Astrophysics, 2006
An analysis of 1236 new electronic spectra of the eclipsing binary EN Lac from four observatories... more An analysis of 1236 new electronic spectra of the eclipsing binary EN Lac from four observatories and of 994 radial velocities (RV hereafter) from photographic spectra, published by several authors, has allowed us to disentangle the RV variations due to orbital motion and due to pulsations of the star. New, accurate orbital elements as well as precise values of the three pulsation periods, already known from the previous studies, were derived. The accuracy of the orbital solution has been substantially improved after the observed RV changes were properly prewhitened for the short-term oscillations. For the first time we present evidence of line profile variations of EN Lac. They correlate well with the short-term RV variations but they alternatively occur with periods corresponding either to the fundamental periods or to the first harmonics of the short-term RV variations. (1 data file).
Astronomy & Astrophysics, 2002
We include existing photometric and spectroscopic material with new observations in a detailed st... more We include existing photometric and spectroscopic material with new observations in a detailed study of the Be+F binary V360 Lac. We used the programs FOTEL and KOREL to derive an improved linear ephemeris and to disentangle the line profiles of both binary components and telluric lines. The BINSYN software suite (described in the paper) is used to calculate synthetic light curves and spectra to fit the UBV photometry, an IUE spectrum, blue and red ground-based spectra, and observed radial-velocity curves. (3 data files).
New systematic BV observations of V497 Cep were carried out at Ege University Observatory. The 0.... more New systematic BV observations of V497 Cep were carried out at Ege University Observatory. The 0.48-m Cassegrain reflector equipped with a SSP-5 photometer and Johnson B and V filters was used. The comparison star already used by Harmanec et al. (1999A&A...346...87H), HD 208440=NGC 7160*3, was used. Its all-sky UBV magnitudes derived by Harmanec et al. were adopted. V497 Cep was observed on 10 nights between July 31, 1999 and October 17, 2000. New electronic spectra of V497 Cep were obtained using two instruments, the 2.6m telescope and spectrograph of the Crimean Astrophysical Observatory, and the 1.2m telescope and Coude spectrograph of the Dominion Astrophysical Observatory. (2 data files).
The analysis of high S/N spectra and photometric data of 60 Cyg shows that: (1) Pronounced long-t... more The analysis of high S/N spectra and photometric data of 60 Cyg shows that: (1) Pronounced long-term variations in spectra are accompanied with light variations. (2) The medium-term variations of RV could indicate that 60 Cyg is a spectroscopic binary. (3) Two independent structures dominate the rapid variability of both spectrum and light of the star.
An analysis of numerous homogenized UBV photoelectric observations and red spectra of the Be star... more An analysis of numerous homogenized UBV photoelectric observations and red spectra of the Be star from several observatories is presented. (4 data files).
Photometric time series in different narrow-band filters are given for the eclipsing binary syste... more Photometric time series in different narrow-band filters are given for the eclipsing binary systems Cyg OB2 #5 = V729 Cyg = BD+40 4220. The data were obtained with the CCD camera at the 1.2m telescope at the Observatoire de Haute Provence. (1 data file).
We discuss the first results of our ongoing optical spectroscopic monitoring campaign of the two ... more We discuss the first results of our ongoing optical spectroscopic monitoring campaign of the two O-type stars 9 Sgr and HD 168112. Both objects display a non-thermal radio emission and were considered as single stars. Based on a large set of high-resolution spectra, we find that 9 Sgr is clearly an eccentric SB2 binary with an orbital period of several years. On the other hand, no evidence for radial velocity variations attributable to binary motion is found in our spectra of HD 168112.
Aims. We present the results obtained from a long-term spectroscopic campaign devoted to the mult... more Aims. We present the results obtained from a long-term spectroscopic campaign devoted to the multiplicity of O-type stars in the young open cluster NGC2244 and in the Mon OB2 association. Methods. Our spectroscopic monitoring was performed over several years, allowing us to probe different time-scales. For each star, several spectral diagnostic tools are applied, in order to search for line shifts and profile variations. We also measure the projected rotational velocity and revisit the spectral classification. Results. In our sample, several stars were previously considered as spectroscopic binaries, though only a few scattered observations were available. Our results now reveal a more complex situation. Our study identifies two new spectroscopic binaries (HD46149 in NGC2244 and HD46573 in MonOB2). The first object is a long-period double-lined spectroscopic binary, though the exact value of its period remains uncertain and the second object is classified as an SB1 system with a period of about 10.67 days but the time series of our observations do not enable us to derive a unique orbital solution for this system. We also classify another star as variable in radial velocity (HD46150) and we detect line profile variations in two rapid rotators (HD46056 and HD46485). Conclusions. This spectroscopic investigation places a firm lower limit (17%) on the binary fraction of O-stars in NGC2244 and reveals the lack of short-period O+OB systems in this cluster. In addition, a comparison of these new results with two other well-studied clusters (NGC6231 and IC1805) puts forward possible hints of a relation between stellar density and binarity, which could provide constraints on the theories about the formation and early evolution of hot stars.
We reported in 2008 the first detection of the binary nature of Cyg OB2 #9. Since then, we have c... more We reported in 2008 the first detection of the binary nature of Cyg OB2 #9. Since then, we have continued our spectroscopic monitoring of this object, doubling the number of available spectra of the star while covering a second periastron passage. Using a variety of techniques, the radial velocities were estimated and a first, preliminary orbital solution was derived (P=2.4 yrs). The mass ratio appears close to unity and the eccentricity is large, 0.7-0.75.
The line profile variability and photometric variability of the O9.5 Vp star HD93521 are examined... more The line profile variability and photometric variability of the O9.5 Vp star HD93521 are examined in order to establish the properties of the non-radial pulsations in this star. Fourier techniques are used to characterize the modulations of the He I 5876, 6678 and H-alpha lines in several spectroscopic time series and to search for variations in a photometric time series. Our spectroscopic data confirm the existence of two periods of 1.75 and 2.89 hr. The line profiles, especially those affected by emission wings, exhibit also modulations on longer time scales, but these are epoch-dependent and change from line to line. Unlike previous claims, we find no unambiguous signature of the rotational period in our data, nor of a third pulsation period (corresponding to a frequency of 2.66 day$^{-1}$). HD 93521 very likely exhibits non-radial pulsations with periods of 1.75 and 2.89 hr with lsimeq8pm1l \simeq 8 \pm 1lsimeq8pm1 and lsimeq4pm1l \simeq 4 \pm 1lsimeq4pm1 respectively. No significant signal is found in the first harmonics of these two periods. The 2.89 hr mode is seen at all epochs and in all lines investigated, while the visibility of the 1.75 hr mode is clearly epoch dependent. Whilst light variations are detected, their connection to these periodicities is not straightforward.
Proceedings of The International Astronomical Union, 2007
After realising that V2368 Oph is a variable star, we started systematic UBV observations of it a... more After realising that V2368 Oph is a variable star, we started systematic UBV observations of it at Hvar and SPM observatories. A limited set of UBV observations was also obtained by HA at the Turkish National Observatory. Simultaneously with photometric observations, we also begun to collect electronic spectra in Ondrejov, San Pedro Martir, and Dominion Astrophysical Observatory. (6 data files).
After a serendipitious discovery that HD 143418 is a light variable, we analyzed numerous UBV obs... more After a serendipitious discovery that HD 143418 is a light variable, we analyzed numerous UBV observations and Hipparcos Hp magnitudes transformed to Johnson V to find out whether the object is a very unusual spectroscopic binary. Initial reductions of new photometry were carried out with the HEC22 program, while the new spectra were reduced in the IRAF and SPEFO programs. Orbital elements were derived with the FOTEL program, the KOREL disentangling was applied, and period searches were carried out using phase dispersion minimalization technique and the program PERIOD04. Final modeling of radial-velocity and light variations was carried out in PHOEBE. (1 data file).
An analysis of new spectroscopic and photoelectric UBV observations, satisfactorily covering the ... more An analysis of new spectroscopic and photoelectric UBV observations, satisfactorily covering the whole orbital period of V436 Per, together with existing data allowed us to improve the knowledge of the basic physical characteristics of the binary and its components. In several aspects, our new results differ from the findings of Paper I (Harmanec et al., 1997, Cat. <J/A+A/319/867>) of this series: In particular, we found that it is the star eclipsed in the secondary minimum which is slightly more massive and larger than the optical primary. We also conclude that the apsidal advance -- if present at all -- is much slower than that estimated in a previous study. The orbital period might be increasing by 0.28 s per year but also this finding is very uncertain and needs verification by future observations. It is encouraging to note that two completely independent sets of programs for light-curve solutions lead to identical results. A notable finding is that both binary components rotate with very similar -- if not identical -- rotational periods of 1.45d and 1.40d, much shorter than what would correspond to a 10.9d spin-orbit synchronization period at periastron. Rapid line-profile changes reported earlier could not be confirmed from new, dedicated series of high-resolution and S/N spectra. (2 data files).
Astronomy & Astrophysics, 2006
An analysis of 1236 new electronic spectra of the eclipsing binary EN Lac from four observatories... more An analysis of 1236 new electronic spectra of the eclipsing binary EN Lac from four observatories and of 994 radial velocities (RV hereafter) from photographic spectra, published by several authors, has allowed us to disentangle the RV variations due to orbital motion and due to pulsations of the star. New, accurate orbital elements as well as precise values of the three pulsation periods, already known from the previous studies, were derived. The accuracy of the orbital solution has been substantially improved after the observed RV changes were properly prewhitened for the short-term oscillations. For the first time we present evidence of line profile variations of EN Lac. They correlate well with the short-term RV variations but they alternatively occur with periods corresponding either to the fundamental periods or to the first harmonics of the short-term RV variations. (1 data file).
Astronomy & Astrophysics, 2002
We include existing photometric and spectroscopic material with new observations in a detailed st... more We include existing photometric and spectroscopic material with new observations in a detailed study of the Be+F binary V360 Lac. We used the programs FOTEL and KOREL to derive an improved linear ephemeris and to disentangle the line profiles of both binary components and telluric lines. The BINSYN software suite (described in the paper) is used to calculate synthetic light curves and spectra to fit the UBV photometry, an IUE spectrum, blue and red ground-based spectra, and observed radial-velocity curves. (3 data files).
New systematic BV observations of V497 Cep were carried out at Ege University Observatory. The 0.... more New systematic BV observations of V497 Cep were carried out at Ege University Observatory. The 0.48-m Cassegrain reflector equipped with a SSP-5 photometer and Johnson B and V filters was used. The comparison star already used by Harmanec et al. (1999A&A...346...87H), HD 208440=NGC 7160*3, was used. Its all-sky UBV magnitudes derived by Harmanec et al. were adopted. V497 Cep was observed on 10 nights between July 31, 1999 and October 17, 2000. New electronic spectra of V497 Cep were obtained using two instruments, the 2.6m telescope and spectrograph of the Crimean Astrophysical Observatory, and the 1.2m telescope and Coude spectrograph of the Dominion Astrophysical Observatory. (2 data files).
The analysis of high S/N spectra and photometric data of 60 Cyg shows that: (1) Pronounced long-t... more The analysis of high S/N spectra and photometric data of 60 Cyg shows that: (1) Pronounced long-term variations in spectra are accompanied with light variations. (2) The medium-term variations of RV could indicate that 60 Cyg is a spectroscopic binary. (3) Two independent structures dominate the rapid variability of both spectrum and light of the star.
An analysis of numerous homogenized UBV photoelectric observations and red spectra of the Be star... more An analysis of numerous homogenized UBV photoelectric observations and red spectra of the Be star from several observatories is presented. (4 data files).