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J/A+A/371/L5        CCD Δa-photometry of NGC 1866      (Maitzen+, 2001)

On the detection of the first extragalactic classical chemically peculiar stars. Maitzen H.M., Paunzen E., Pintado O.I. <Astron. Astrophys. 371, L5 (2001)> =2001A&A...371...L5M
ADC_Keywords: Magellanic Clouds ; Photometry, narrow-band ; Stars, peculiar Keywords: galaxies: Magellanic Clouds - stars: chemically peculiar - stars: early-type Abstract: We report on the detection of the first extragalactic, classical chemically peculiar (CP) stars more than 100 years after the discovery of this group. Using the tool of CCD Δa-photometry, eight definite positive detections in the globular-like stellar cluster NGC 1866 and its surrounding in the Large Magellanic Cloud were made. More than 1950 objects within a radius of 9.5' of the cluster center down to 20.5 magnitude were observed in this three filter, narrow band photometric system. Averaging more than 70 individual frames for all three filters yielded a 3σ detection limit of 0.015mag for stars with V=20mag. Furthermore we found three objects with significantly negative Δa-values indicating either an Ae/shell or λ Bootis nature. The overall percentage of chemically peculiar stars for NGC 1866 (1.5%) seems lower than for the majority of open clusters in our Milky Way whereas the incidence within the LMC field is decisively less (0.3%). For a description of the Δa photometric system, see e.g. GCPD/75 Objects: ---------------------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------------------- 05 13 39.0 -65 27 54 NGC 1866 ---------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 74 301 Observed program stars within 1.5' of NGC 1866 table2.dat 74 1678 Observed program stars in the surrounding of NGC 1866
See also: J/AJ/118/2839 : BV photometry of NGC 1866 (Testa+, 1999) J/ApJS/71/25 : NGC 1866 CCD photometry (Brocato+ 1989) J/A+A/373/153 : NGC 2489, 2567, 2658, 5281 and 6208 (Paunzen+, 2001) J/A+A/385/867 : NGC 2439, 3960, 6134, 6192 and 6451 (Paunzen+, 2002) J/A+A/395/823 : Collinder 272, Pismis 20, Lynga 14, NGC 6396 and 6611 (Paunzen+, 2002) J/A+A/412/721 : NGC 2099, 3114, 6204, 6705 and 6756 (Paunzen+, 2003) Byte-by-byte Description of file: table1.dat table2.dat
Bytes Format Units Label Explanations
1- 4 I4 --- Seq Notation for stars sorted after X and Y 6- 10 I5 --- TFC ? Notation according to Testa et al. (1999, Cat. J/AJ/118/2839) 12- 18 F7.2 pix Xpos X-coordinate (1pix=0.813") 20- 26 F7.2 pix Ypos Y-coordinate (1pix=0.813") 28- 33 F6.3 mag g1-y Mean (g1-y) index (1) 35- 39 F5.3 mag e_g1-y rms uncertainty on (g1-y) 41- 45 F5.3 mag a Mean a index (a = g2 - [(g1+y)/2]) (1) 47- 51 F5.3 mag e_a rms uncertainty on a 53- 58 F6.3 mag Deltaa Deviation from cluster line (2) 60- 65 F6.3 mag ymag Mean y value (1) 67- 71 F5.3 mag e_ymag rms uncertainty on ymag 73- 74 I2 --- N Number of measurements
Note (1): CCD filter photometry in the narrow band Δa-system introduced by Maitzen (1976A&A....51..223M). g1 is at 500nm, y at 550nm, both representing the continuum at the edges of the feature, and g2 is located at the center of the feature at 521nm. Note (2): Magnitude difference of g2 relative to the mean of g1 and y, normalized to zero for a non-peculiar star
Acknowledgements: Ernst Paunzen References: Bayer et al., Paper I 2000A&AS..147...99B Paunzen & Maitzen, Paper II 2001A&A...373..153P, Cat. J/A+A/373/153 Paunzen & Maitzen, Paper III 2002A&A...385..867P, Cat. J/A+A/385/867 Paunzen et al., Paper IV 2002A&A...395..823P, Cat. J/A+A/395/823
(End) Ernst Paunzen [IfA, Vienna], Patricia Bauer [CDS] 28-May-2001
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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