HD 52721 - A close binary system among the Ae/Be Herbig stars

Погодин, М. А.; Beskrovnaya, N. G.; Guseva, I. S.; Pavlovskiy, S. E.; Rusomarov, N.

doi:10.1007/s10511-011-9173-x

Cited by 4 publications

(12 citation statements)

References 6 publications

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“…At phases 0.23−0.33 from the main minimum (Fig. 5), the light curve exhibited a wave-like jump in brightness; according to the ASAS data (see Pogodin et al 2011), a similar feature was present at the same phases in 2003-2009. Besides, a low-amplitude local minimum at a phase of about 0.8 from the main minimum was also observed in 2013 (Fig.…”

Section: Results and Their Discussionmentioning

confidence: 71%

“…Unfortunately, the phase light curve obtained previously in our first observations in 2010 (see Pogodin et al 2011) was insufficiently complete. At least 25 photometric nights are required to obtain a detailed light curve of this star with the period P = 1 d .610.…”

Section: Observationsmentioning

confidence: 69%

“…6), an interesting close binary system. The first results of our investigation of this star were published in and Pogodin et al (2011. A detailed review of the results obtained previously by other researchers is also given in these papers.…”

Section: Introductionmentioning

confidence: 76%

“…A stable wave of brightness variations at phase 0.3 (measured from the deepest photometric minimum) with an amplitude of ∼0 m . 03 persisting during the entire 7-year period of observations is clearly seen on the phase light curve (Pogodin et al 2011). The secondary lowamplitude brightness minimum was also noticed by Praderie et al (1991), who presented the results of a short set of photometric observations (more than 100 UBVRI measurements during five nights in 1985).…”

Section: Introductionmentioning

confidence: 85%

“…The observations were made in integrated light (without filters). The spectral sensitivity curve of the instrumentation is presented in Pogodin et al (2011). During the observations, the array of the CCD camera was cooled to temperatures within the range from −20 to −30 • C, depending on the ambient temperature.…”

Section: Observationsmentioning

confidence: 99%

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New photometric investigation of the Herbig Ae/Be star HD 52721, a close binary system: Evidence for the existence of large-scale azimuthal inhomogeneities

et al. 2015

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We present new results of our photometry for the Herbig Be star HD 52721 obtained from January 16 to March 25, 2013. A new data reduction technique is used. Using this technique, we have also reanalyzed the previous results of our photometry for this object pertaining to the period from March 7 to March 28, 2010. The Be star HD 52721 is known as an eclipsing variable with the period P = 1 d .610. Two photometric minima observed during one period are a peculiarity of its photometric variability. They are separated in phase of the period P by 0.5 and differ from one another in depth by 0 m . 04. We have also detected additional minima observed at the phases of maximum brightness. We hypothesize that they can be associated with the existence of local azimuthal inhomogeneities rotating synchronously with the orbital motion of the binary component stars in the circumstellar envelope. When processing our CCD frames, we have applied an efficient CCD-frame rejection method that has allowed the accuracy of observations to be increased considerably. The CCD frames have been further processed using the Apex II software package, which is a universal software platform for astronomical image processing. We justify the need for additional photometric observations of HD 52721 in various color bands to confirm the hypothesis about the existence of azimuthal inhomogeneities in the program binary system and to analyze their physical properties.

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Section: Results and Their Discussionmentioning

confidence: 71%

Section: Observationsmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 76%

Section: Introductionmentioning

confidence: 85%

Section: Observationsmentioning

confidence: 99%

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New photometric investigation of the Herbig Ae/Be star HD 52721, a close binary system: Evidence for the existence of large-scale azimuthal inhomogeneities

et al. 2015

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The Be Herbig Star HD 52721 – New Signs of Binarity

et al. 2013

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Photometric and high-resolution spectral data on the Be Herbig star HD 52721 from our earlier article [1] are supplemented by new data obtained with an echelle spectrograph mounted on the 2.1-m telescope at the San Pedro Martir Observatory (Ensenada, Mexico). BVR photometry data obtained during 1987-1998 at the Maidanak Observatory (Uzbekistan) are also examined in more detail. This confirms that the phase light curve for an orbital period P=1 d .610 has two minima with different depths separated in phase by 0.5, and reveals a reddening of the object at the phases of the minima. The profiles of atmospheric He I lines in the 4000-4500 Å range are found to be broader, shallower, and more asymmetric at the brightness maximum than at the minimum, as expected in close binary systems. Various factors which may influence the formation of the observed atmospheric line profiles are discussed. The observations confirm the hypothesis of a dense disk shaped gas envelope surrounding the system that makes a significant contribution to its overall brightness and contains a global azimuthal inhomogeneity rotating in synchrony with the orbital motion of the system components. We emphasize the need for new photometric observations of HD 52721 in the region of the atmospheric lines, as well as a continuation of the photometric program, in order to confirm the existence of and to analyze the stable, small variations in the light curve of this object.

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Spectro-astrometry of the pre-transitional star LkCa 15 does not reveal an accreting planet but extended Hα emission

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Oudmaijer

Schneider

et al. 2018

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Context. The detection of forming planets in protoplanetary disks around young stars remains elusive, and state-of-the-art observational techniques provide somewhat ambiguous results. The pre-transitional T Tauri star LkCa 15 is an excellent example. It has been reported that it could host three planets; candidate planet b is in the process of formation, as inferred from its Hα emission. However, a more recent work casts doubts on the planetary nature of the previous detections. Aims. We test the potential of spectro-astrometry in Hα as an alternative observational technique to detect forming planets around young stars, taking LkCa 15 as a reference case Methods. LkCa 15 was observed with the ISIS spectrograph at the 4.2m William Herschel Telescope (WHT). The slit was oriented towards the last reported position of LkCa 15 b (parallel direction) and 90 • from that (perpendicular). The photocenter and full width half maximum (FWHM) of the Gaussians fitting the spatial distribution at Hα and the adjacent continuum were measured. A well-known binary (GU CMa) was used as a calibrator to test the spectro-astrometric performance of ISIS/WHT. Results. A consistent spectro-astrometric signature is recovered for GU CMa. However, the photocenter shift predicted for LkCa 15 b is not detected, but the FWHM in Hα is broader than in the continuum for both slit positions. Our simulations show that the photocenter and FWHM observations cannot be explained simultaneously by an accreting planet, but the lack of photocenter shift alone could still be consistent with an emitting planet with contrast 5.5 mags in Hα or 6 mag in the adjacent continuum. In turn, both spectro-astrometric observations are naturally reproduced from a roughly symmetric Hα emitting region centered on the star and extent comparable to the orbit originally attributed to the planet at several au. Conclusions. The extended Hα emission around LkCa 15 could be related to a variable disk wind, but additional multi-epoch data and detailed modeling are necessary to understand its physical nature. Optical spectro-astrometry carried out with mid-size telescopes is capable of probing small-scale structures in relatively faint young stars that are not easily accessible with state-of-the-art instrumentation mounted on larger telescopes. Therefore, spectro-astrometry in Hα is able to test the presence of accreting planets and can be used as a complementary technique to survey planet formation in circumstellar disks.

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HD 52721 - A close binary system among the Ae/Be Herbig stars

Cited by 4 publications

References 6 publications

New photometric investigation of the Herbig Ae/Be star HD 52721, a close binary system: Evidence for the existence of large-scale azimuthal inhomogeneities

New photometric investigation of the Herbig Ae/Be star HD 52721, a close binary system: Evidence for the existence of large-scale azimuthal inhomogeneities

The Be Herbig Star HD 52721 – New Signs of Binarity

Spectro-astrometry of the pre-transitional star LkCa 15 does not reveal an accreting planet but extended Hα emission

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