J/A+AS/139/231 Early-type stars towards the Galactic Centre (Dufton+, 1999)
A UKST survey of blue objects towards the Galactic Centre -
a search for early-type stars.
Dufton P.L., Smartt S.J., Hambly N.C.
<Astron. Astrophys. Suppl. Ser. 139, 231 (1999)>
=1999A&AS..139..231D 1999A&AS..139..231D
ADC_Keywords: Stars, early-type ; Stars, blue ; Photometry, photographic ;
Equivalent widths
Keywords: stars: early-type - stars: fundamental parameters - stars: imaging -
galaxy: center
Abstract:
We have begun a search for early-type stars towards the galactic
centre which are potentially young objects situated within the inner
few kiloparsecs of the disk. U and V (or I) band photographic
photometry from the UK Schmidt Telescope has been obtained to identify
the bluest candidates in nineteen Schmidt fields (centred close to the
galactic centre). We have spectroscopically observed these targets for
three fields with the FLAIR multi-fibre system to determine their
spectral types. In particular, ten early B-type stars have been
identified and equivalent width measurements of their Balmer and HeI
lines have been used to estimate atmospheric parameters. These
early-type objects have magnitudes in the range 11.5=<V≤16.0, and our
best estimates of their distance (given probable highly variable
reddening in this direction together with errors in the plate
photometry) suggest that some of them originated close to (i.e
Rg<3kpc), or even beyond the galactic centre. Future high-resolution
spectroscopy of these stars will provide reliable atmospheric
parameters and element abundances, in order to map the current
chemical composition of the inner galaxy.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 43 122 Blue stellar candidates for which spectroscopy
was not obtained
table3.dat 106 48 *Field 393 preliminary identifications of targets
table4.dat 104 31 Field 454 preliminary identifications of targets
table5.dat 108 46 Field 456 preliminary identifications of targets
table6.dat 87 36 *Equivalent widths for early-type candidates
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Note on table3.dat: For the two possible PN's identified in this field, no
object in the SIMBAD catalogue was found within 2' of their positions
Note on table6.dat: Also listed are the estimated atmospheric parameters
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See also:
J/A+A/373/608 : Early-type stars towards the Galactic Center (Dufton+, 2001)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1 A1 --- f_Star [+] when the star is also in table6
2- 4 I3 --- Field Field number (1)
7- 8 I2 --- Star Star number in the field (1)
10- 11 I2 h RAh Right ascension (J2000)
13- 14 I2 min RAm Right ascension (J2000)
16- 20 F5.2 s RAs Right ascension (J2000)
22 A1 --- DE- Declination sign (J2000)
23- 24 I2 deg DEd Declination (J2000)
26- 27 I2 arcmin DEm Declination (J2000)
29- 32 F4.1 arcsec DEs Declination (J2000)
34- 38 F5.2 mag Vmag V magnitude (I for field 456)
40- 44 F5.2 mag (u-v) (u-v) colour index (u-i for field 456)
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Note (1): In Simbad, the stars are identified as
[DSH99] 393-NN, [DSH99] 454-NN, [DSH99] 456-NN
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Byte-by-byte Description of file: table[34].dat
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Bytes Format Units Label Explanations
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1 A1 --- f_Star [+] when the star is also in table6
2- 4 I3 --- Field Field number
7- 8 I2 --- Star Star number in the field
11- 12 I2 h RAh Right ascension (J2000)
14- 15 I2 min RAm Right ascension (J2000)
17- 21 F5.2 s RAs Right ascension (J2000)
23 A1 --- DE- Declination sign (J2000)
24- 25 I2 deg DEd Declination (J2000)
27- 28 I2 arcmin DEm Declination (J2000)
30- 33 F4.1 arcsec DEs Declination (J2000)
35- 39 F5.2 mag Vmag V magnitude
41- 45 F5.2 mag (u-v) u-v colour index
47- 50 I4 --- Count Mean stellar count
52- 96 A45 --- Com Comments
98-107 A10 --- SpType Spectral type
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1 A1 --- f_Star [+] when the star is also in table6
2- 4 I3 --- Field [456] Field number
7- 8 I2 --- Star Star number in the field
11- 12 I2 h RAh Right ascension (J2000)
14- 15 I2 min RAm Right ascension (J2000)
17- 21 F5.2 s RAs Right ascension (J2000)
23 A1 --- DE- Declination sign (J2000)
24- 25 I2 deg DEd Declination (J2000)
27- 28 I2 arcmin DEm Declination (J2000)
30- 33 F4.1 arcsec DEs Declination (J2000)
35- 39 F5.2 mag Imag I magnitude
41- 45 F5.2 mag u-i u-i colour index
47- 50 I4 --- Cb Mean blue (3900Å to 4600Å) stellar count
51 A1 --- --- [/]
52- 55 I4 --- Cr Mean red (5600Å to 6800Å) stellar count
57-100 A44 --- Com Comments
102-111 A10 --- SpType Spectral type
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1 A1 --- Type [EML] Star type (1)
3- 5 I3 --- Field Field number
8- 9 I2 --- Star Star number in the field
11- 14 I4 --- Mean Mean stellar count
16- 19 F4.1 0.1nm EW3970 ? Balmer (3970Å) equivalent width
20 A1 --- u_EW3970 Marginal measurement
22- 24 F3.1 0.1nm EW4101 ? Hε (4101Å) equivalent width
25 A1 --- u_EW4101 Marginal measurement
26 A1 --- n_EW4101 Note on the presence of line EW4101 (2)
28- 30 F3.1 0.1nm EW4340 Hδ (4340Å) equivalent width
31 A1 --- u_EW4340 Marginal measurement
33- 35 F3.1 0.1nm EW4026 ? Hγ (4026Å) equivalent width
36 A1 --- u_EW4026 Marginal measurement
37- 38 A2 --- n_EW4026 Note on the presence of line EW4026 (2)
40- 42 F3.1 0.1nm EW4143 ? He I (4143Å) equivalent width
43 A1 --- u_EW4143 Marginal measurement
44- 45 A2 --- n_EW4143 Note on the presence of line EW4143 (2)
47- 49 F3.1 0.1nm EW4387 ? He I (4387Å) equivalent width
50 A1 --- u_EW4387 Marginal measurement
51- 52 A2 --- n_EW4387 Note on the presence of line EW4387 (2)
54- 56 F3.1 0.1nm EW4471 ? He I (4471Å) equivalent width
57 A1 --- u_EW4471 Marginal measurement
59- 61 F3.1 0.1nm EW4481 ? MgII (4481Å) equivalent width
62 A1 --- u_EW4481 Marginal measurement
63- 64 A2 --- n_EW4481 Note on the presence of line EW4481 (2)
66- 68 F3.1 0.1nm EW3933 ? Ca II (3933Å) equivalent width
69 A1 --- u_EW3933 Marginal measurement
70- 71 A2 --- n_EW3933 Note on the presence of line EW3933 (2)
73- 74 A2 --- l_Teff [<≥ ] Limit flag on Teff
75- 79 I5 K Teff Effective temperature
80 A1 --- u_Teff Marginal measurement
82- 83 A2 --- l_logg [<≥ ] Limit flag on logg
84- 86 F3.1 [cm/s2] logg Surface gravity
87 A1 --- u_logg Marginal measurement
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Note (1): E: Early B-type, M: Mid B-type, L: Late B or A-type
Note (2): the meaning of the symbols are:
p: a line is present but its strength cannot be reliably estimated
p?: a line may be present
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History: Prepared via OCR at CDS.
(End) James Marcout, Patricia Bauer [CDS] 27-Apr-2000