ADC/CDS Standard Document for Catalog:/journal_tables/AJ/98/1305/
ADC/CDS Standard Document for Catalog:| 1. Use the ADC Data Viewer Suite to visualize the data. |
|
| 2. Get the data files via anonymous FTP. (See Note.) |
|
J/AJ/98/1305 Stellar content of NGC 346 (Massey+, 1989)
================================================================================
The stellar content of NGC 346: a plethora of O stars in the SMC
Massey P., Parker J.W., Garmany C.D.
<Astron. J. 98, 1305 (1989)>
=1989AJ.....98.1305M (SIMBAD/NED Reference)
================================================================================
ADC_Keywords: H II regions; Magellanic clouds; Nebulae; Stars, O;
Stars, Wolf-Rayet; Spectrophotometry
Description:
Using CCD UBV photometry and spectroscopy, we have investigated the
stellar content of NGC 346, the brightest H II region in the SMC.
Spectra of 42 stars confirm that 33 are of O type, of which 11 are
of type O6.5 or earlier; this is as many early-type O stars as is
known in the rest of the SMC. From the spectroscopy and photometry
we are able to construct an H-R diagram which is essentially complete
down to ~10M_{sun}_. We find an initial mass-function slope
{GAMMA}=-1.9, similar to that found for massive stars near the Sun
and in the LMC: the presence of six stars in the mass range
40-85M_{sun}_ suggests that the upper-mass limit of the IMF is also
not appreciably lower in the SMC than it is in the Galaxy.
Our photometry has identified five probable red supergiants of
which one was previously known. These stars, plus two B supergiants,
are evolved stars of considerably lower mass (15M_{sun}_) than
many of the unevolved cluster members. Most of these lower-mass,
evolved stars form a spatially distinct subgroup; we believe that
NGC 346 thus provides an example of sequential star formation in
the SMC. We also have identified a background field population of
5M_{sun}_ stars. We find that the ionizing flux from the hot stars
is consistent with the previously known Half nebular luminosity.
Finally, we discuss the enigmatic W-R binary HD 5980, which our
point-spread-function fitting has identified as a close visual double.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 47 876 Photometry of NGC 346
table5.dat 49 56 Comparison with Niemela et al. (1986)
table7.dat 100 8 Other bright stars in NGC 346
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Id Star number
8- 12 F5.1 pix Xpos X position
15- 20 F6.1 pix Ypos Y position
23- 27 F5.2 mag Vmag V magnitude
28- 29 A2 --- u_Vmag [: ] Uncertainty flag on Vmag (1)
32- 36 F5.2 mag U-B U-B colour index
37- 38 A2 --- u_U-B [: ] Uncertainty flag on U-B (1)
41- 45 F5.2 mag B-V B-V colour index
46- 47 A2 --- u_B-V [: ] Uncertainty flag on B-V (1)
--------------------------------------------------------------------------------
Note (1): A colon indicates measurement whose error is twice as big as that
given in table3, two colons denote those stars whose photometry
has errors which are >=3{sigma}. In addition, colons are used to
denote stars whose photometry is outside the range well fit by
colour transformations.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Id Star number
4- 11 A8 --- m_Id Other star numbers when multiple star
14- 15 I2 --- NameN []? Niemela star number
22- 26 F5.2 mag Vmag V magnitude from this work
27- 28 A2 --- u_Vmag [: ] Uncertainty flag on Vmag
30- 34 F5.2 mag VmagN V magnitude from Niemela
37- 56 A20 --- Rem Remarks (1)
--------------------------------------------------------------------------------
Note (1): *: also identified as multiple by Niemela et al.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Id Star number
8- 9 I2 h RAh Right ascension 1950
11- 12 I2 min RAm Right ascension 1950
14- 18 F5.2 s RAs Right ascension 1950
20 A1 --- DE- Declination sign
21- 22 I2 deg DEd Declination 1950
24- 25 I2 arcmin DEm Declination 1950
27- 30 F4.1 arcsec DEs Declination 1950
35- 39 F5.1 pix Xpos X position
42- 46 F5.1 pix Ypos Y position
49- 53 F5.2 mag Vmag V magnitude
54- 55 A2 --- u_Vmag [: ] Uncertainty flag on Vmag
57- 61 F5.2 mag U-B U-B colour index
62- 63 A2 --- u_U-B [: ] Uncertainty flag on U-B
66- 69 F4.2 mag B-V B-V colour index
70- 71 A2 --- u_B-V [: ] Uncertainty flag on B-V
73-112 A40 --- Com Comments (1)
--------------------------------------------------------------------------------
Note (1): References:
PMMRR = Prevot et al. (1983)
Sanduleak = Sanduleak (1989)
--------------------------------------------------------------------------------
Historical Notes: Keypunched at CDS
References:
Niemela V.S. et al., 1986, Publ. Astron. Soc. Pac., 98, 1133
Prevot L. et al., 1983, Astron. Astrophys. Suppl., 53, 255
Sanduleak N., 1989, Astron. J. (to be submitted)
================================================================================
(End) Marie-Jose Wagner, Patricia Bauer [CDS] 02-Mar-1995