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Astron. Astrophys. 344, 143-150 (1999)

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Appendix A: position angle (P.A.) measurements: notes on individual objects

HD168625 : The emission nebula surrounding HD168625 consists of an elliptical ring from which seems to emerge a bipolar nebula (Hutsemékers et al. 1994, Nota et al. 1996). After several measurements from these published images, we estimate the long bipolar axis to be oriented at P.A. = 29[FORMULA] 5o.

G25.5+0.2 : On the radio and near-infrared images displayed by Subrahmanyan et al. (1993), the very distant nebula G25.5+0.2 appears roughly bipolar, with two brighter condensations along the minor axis. From these images, we estimate P.A. = 128[FORMULA] 5o for the long nebular axis.

M1-67 : The nebula M1-67 is associated with the WN8 star 209 BAC (WR124). On the images in Chu & Treffers (1981) and Solf & Carsenty (1982) it appears as a clumpy nebula without definite bipolar or elliptical morphology. It is nevertheless elongated along one direction, and Solf & Carsenty (1982) give P.A. [FORMULA]20o for its long axis. On the basis on these published images plus new ones obtained with EFOSC, we adopt P.A. = 25[FORMULA] 10o.

NGC6888 : The nebula NGC6888 surrounding the WN6 star HD 192163 (WR136) is nicely illustrated in Miller & Chu (1993). The overall morphology looks roughly elliptical, or bipolar with a possible "waist". Marston & Meaburn (1988) give P.A. = 35o for the long axis orientation. After additional measurements from the Miller & Chu (1993) H[FORMULA]+[NII ] image, we adopt P.A. = 38[FORMULA] 3o.

G79.29+0.46 : The nebula G79.29+0.46 has been imaged at radio wavelengths by Higgs et al. (1994). The nebula appears as a nearly circular ring, slightly elongated in the north-east direction. A faint spur is also seen in this direction, external to the ring. We adopt P.A. = 45[FORMULA] 10o for the major axis of the ellipse.

S308 : The nebula S308 surrounds the WN5 star HD50896 (WR6). On the [OIII ] images shown by Chu et al. (1982), the nebula appears nearly circular with a funnel-shaped elongation. Although this morphology is less typical (as compared to younger LBV nebulae), it is nevertheless reminiscent of a bipolar lobe (rather small here) with brighter condensations along the perpendicular axis. We therefore assume the long axis going through this elongation and we adopt P.A. = 146[FORMULA] 10o. Note that a distant funnel-shaped nebulosity aligned with the nebula long axis has been found in the vicinity of HR Car (Weis et al. 1997).

HR Car : The HR Car nebula was recently identified as a true bipolar nebula by Weis et al. (1997) and Nota et al. (1997). These authors respectively give P.A. = 125o and 135o for the nebula long bipolar axis. We adopt P.A. = 130[FORMULA] 5o. The comparison with the discovery images in Hutsemékers & Van Drom (1991a) illustrates the importance of good quality data for measuring accurate position angles.

[FORMULA] Car : The famous homunculus surrounding [FORMULA] Car is mainly a reflection nebula whose morphology is clearly bipolar. The orientation of its long axis is well defined and Meaburn et al. (1993) give P.A. = 132o. We adopt P.A. = 132[FORMULA] 2o.

He3-519 : The nebula around He3-519 appears as an elliptical ring, roughly box-shaped (Stahl, 1987). The P.A. of the major axis is measured from the image shown in Stahl (1987), plus additional ones we obtained with EFOSC. We find P.A. = 34[FORMULA] 5o.

AG Car : The emission nebula around AG Car is ring-like, roughly elliptical. Smith (1991) and Schulte-Ladbeck et al. (1994) respectively give P.A. = 131o and 135o for the major axis. After additional measurements namely from our EFOSC images, we adopt a mean P.A. of 132[FORMULA] 3o.

WRA751 : On the images shown in Hutsemékers & Van Drom (1991b), the nebula around WRA751 appears nearly circular, slightly extended along P.A. [FORMULA] 160o. Additional images obtained with EFOSC reveal a more complex ring-like morphology with arcs and ansae. The orientation of the long axis lies between P.A. = 145o and 165o. We adopt P.A. = 155[FORMULA] 10o.

RCW58 : The nebula RCW58 surrounds the WN8 star HD96548 (WR40). In H[FORMULA] it appears as an elliptical ring (Chu 1982, Smith et al. 1988, Marston 1996). When measured from these published images, we estimate the major axis to be oriented at P.A. = 8[FORMULA]5o.

Br13 : The nebula around the WN8 star Br13 in the LMC appears elliptical on the H[FORMULA] images displayed by Garnett & Chu (1994). From these images, we measure P.A. = 47[FORMULA]3o for the major axis.

S119 : Nota et al. (1995) found the nebula surrounding the LMC Of/WN star S119 apparently elliptical with a very bright condensation along the minor axis. From their published [FORMULA] image, we estimate the major axis to be oriented at P.A. = 133[FORMULA]5o.

SN1987A : Although its true nature is far from clear, the three-ring nebula associated with SN1987A in the LMC has an overall bipolar morphology (Burrows et al. 1995). Using Hubble Space Telescope images available in the literature (Burrows et al. 1995, Panagia et al. 1996), we measure P.A. = 168[FORMULA]5o for the long axis of the whole nebula.

R127 : Images of the nebula surrounding the LBV R127 in the LMC are shown in Clampin et al. (1993) and Nota et al. (1995). The nebula is essentially elliptical. Clampin et al. (1993) found the major axis lying at P.A. = 165o. Since the definition of the axis may be affected by the subtraction of neighbouring stars (cf. Clampin et al. 1993), we also take into account the P.A. of the minor axis, assuming it is perpendicular to the major one. Schulte-Ladbeck et al. (1993) have estimated the P.A. of the minor axis between 90o and 100o. After some additional measurements, we adopt P.A. = 180[FORMULA]10o for the orientation of the nebula major axis.

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Online publication: March 10, 1999