Speckle Masking Observations of the Young Binary Z CMa

W. Barth, G. Weigelt, and H. Zinnecker

Astronomy and Astrophysics, v.291, p.500-504 (1994)


We present the first speckle masking observations of the pre-main sequence binary system Z canis majoris (Z CMa) at optical wavelengths (narrow-band R filter and edge filter RG 610). The diffraction-limited images confirm that Z CMa is a binary with a separation of 0.100'' ± 0.008'' at position angle 305° ± 2°. The intensity ratio of the stars is 7.2 for the narrow-band R filter and 7.7 for the RG610 filter. The south-eastern component is the brighter component (i.e. the FU Ori object), in agreement with the results of Koresko et al. (1991) based on near-infrared speckle data. However, our optical detection of the north-western component (the infrared companion) would not have been expected according to Koresko et al.'s analysis. One possible explanation could be scattered light. This agrees with recent polarimetric evidence from Whitney at a. (1993) that scattering plays a role in seeing the infrared companion. We discuss the possiblity that both components of the Z CMa system may be FU Ori objects.

You can get this publication by following this link to the ADS website.

Simultaneous Optical Speckle Masking and NIR adaptive Optics Imaging of the 126 mas Herbig Ae/Be Binary Star NX Puppis

M. Schöller, W. Brandner, T. Lehmann, G. Weigelt, and H. Zinnecker

Astronomy and Astrophysics, v.315, p.445-452 (1996)


We present simultaneous optical and near-infrared high angular resolution observations of the close Herbig Ae/Be binary star NX Pup which is associated with cometary globule 1. The reconstructed images have a diffraction-limited resolution of 62mas in V, 75mas in R (speckle masking reconstruction), and 115mas in H, 156mas in K (adaptive optics + post-processing). Compared to previous results we were able to derive better estimates on spectral type and luminosity and hence put better constraints on the evolutionary status (mass & age) of NX Pup A and B: with NX Pup A of spectral type F0-F2 we estimate the spectral type of NX Pup B in the range F7-G4, masses of 2M and 1.6 - 1.9 M, respectively, and an age of 3 - 5 Myr for both stars.

We discuss the implication of the new age determination on the physical relation between NX Pup and the cometary globule. The dynamical lifetime of ≈ 106yr for cometary globule 1 suggests that cometary globule 1 and the nearby cometary globule 2 represent transient phenomena and are left overs of a larger molecular cloud which in turn was the parental cloud of NX Pup A and B and finally got dispersed by photoevaporation.

The IR excess of NX Pup A can be modeled by a viscous accretion disk, which is cut off at ≈ 20AU from the star. NX Pup B has a smaller IR excess which indicates that there is less circumstellar material present than around the primary.

You can get this publication by following this link to the ADS website.

Photopolarimetric activity and circumstellar environment of the young binary system DF Tau

Shakhovskoj, D., Grinin, V., Rostopchina, A., Schertl, D., Hofmann, K.-H., Weigelt, G., Balega, Yu., Kiyaeva, O., and Melnikov, S.

Astronomy & Astrophysics, 448, pg.1075-1082 (2006)


We present the results of multi-year photometric and polarimetric observations of the young binary system DF Tau in the UBVRI bands, as well as bispectrum speckle interferometric observations in the H and K bands obtained between 2001 and 2003. The photometric and polarimetric observations suggest that the linear polarization of DF Tau does not depend on its brightness, and the polarization variation has a stochastic character. This result confirms earlier suggestions about the dominant role of hot accretion spots in the photometric activity of this star. We argue that the hot spots are at high latitudes and/or the star rotation axis is inclined to the line-of-sight. The influence of circumstellar (CS) dust on the variability is probably small since the inclination of the primary's CS disk to the line-of-sight is large. Using the total mass of the binary system DF Tau from Hartigan & Kenyon (2003, ApJ, 583, 334), we calculated new orbital parameters of the system. The new value of the orbital period (P = 74.1 yr) disagrees with the photometric cycle of about 40 yr revealed by Lamzin et al. (2001b, A&A, 372, 922) from analysis of the historical light curve of this star. This suggests that this cycle is not caused by the orbital motions of the binary components, but probably reflects the cyclical variability of the global magnetic field on the main component.

You can get this publication by following this link to the ADS website.

Speckle interferometry of the HAeBe star V376 Cas

Smith, K.W., Balega, Y.Y., Hofmann, K.-H., Preibisch, Th., Schertl, D., Weigelt, G.

Astronomy and Astrophysics 413, 217 (2004)


We report H- and K'-band speckle interferometric observations of the HAeBe star V376 Cas. Our observations show that the object is partially resolved. The visibility curves suggest three separate components: a large scattering envelope visible only in the H band, a component approximately 100 mas in radius, and a component with a Gaussian HWHM of approximately 8±3 mas, corresponding to approximately 5 AU at 600 pc distance, which contributes most of the flux. We compare the smallest structure to the radius of dust sublimation in the radiation field of the star and find that the radius is approximately six times larger than that expected. This may indicate that the inner regions of the system are in fact obscured by a flaring circumstellar disk or torus seen close to edge-on.

You can get this publication by following this link to the ADS website.

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