J/MNRAS/426/1235 UVEX sources spectroscopic follow-up (Verbeek+, 2012)
Spectroscopic follow-up of ultraviolet-excess objects selected from the
UVEX survey.
Verbeek K., Groot P.J., Scaringi S., Napiwotzki R., Spikings B.,
Ostensen R.H., Drew J.E., Steeghs D., Casares J., Corral-Santana J.M.,
Corradi R.L.M., Deacon N., Drake J.J., Gansicke B.T., Gonzalez-Solares E.,
Greimel R., Heber U., Irwin M.J., Knigge C., Nelemans G.
<Mon. Not. R. Astron. Soc., 426, 1235-1261 (2012)>
=2012MNRAS.426.1235V 2012MNRAS.426.1235V
ADC_Keywords: Ultraviolet ; Stars, subdwarf ; Stars, white dwarf ; Photometry
Keywords: surveys - subdwarfs - white dwarfs - ISM: general - Galaxy: disc -
Galaxy: stellar content
Abstract:
We present the results of the first spectroscopic follow-up of 132
optically blue ultraviolet (UV)-excess sources selected from the
UV-Excess Survey of the Northern Galactic Plane (UVEX). The UV-excess
spectra are classified into different populations and grids of model
spectra are fitted to determine spectral types, temperatures, surface
gravities and reddening. From this initial spectroscopic follow-up 95
per cent of the UV-excess candidates turn out to be genuine UV-excess
sources such as white dwarfs, white dwarf binaries, subdwarf types O
and B, emission-line stars and quasi stellar objects. The remaining
sources are classified as slightly reddened main-sequence stars with
spectral types later than A0V. The fraction of DA white dwarfs is 47
per cent with reddening smaller than E(B-V)≤0.7mag.
Relations between the different populations and their UVEX photometry,
Galactic latitude and reddening are shown. A larger fraction of UVEX
white dwarfs is found at magnitudes fainter than g>17 and Galactic
latitude smaller than |b|<4 compared to main-sequence stars, blue
horizontal branch stars and subdwarfs.
Description:
Spectroscopic follow-up was obtained by three different telescopes for
a total of 132 UV-excess candidates during a number of observing runs.
For 100 UV-excess candidates spectroscopic observations were obtained,
during two runs in 2009 September and 2010 December, with the
Intermediate dispersion Spectrograph and Imaging System (ISIS) mounted
at the 4.2m William Herschel Telescope (WHT) at Roque de los
Muchachos Observatory on the island of La Palma.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 144 132 Classifications of the UV-excess spectra
table2.dat 53 46 Results of the two fitting methods for WHT/ISIS
UV-excess spectra classified as white dwarfs
table3.dat 53 22 Results of the fitting for UV-excess spectra
classified as subdwarfs, MS and BHB stars
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See also:
J/MNRAS/420/1115 : UV-excess sources from UVEX (Verbeek+, 2012)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/132] Spectrum number
5- 8 A4 --- --- [UVEX]
9- 27 A19 --- UVEX UVEX name, JHHMMSS.ss+DDMMSS.s
29- 37 F9.5 deg GLON Galactic longitude
39- 46 F8.5 deg GLAT Galactic latitude
48- 51 I4 --- Field UVEX field in which the object was selected
53- 56 I4 --- Sel UVEX selection flag (1)
58- 63 F6.3 mag gmag UVEX g magnitude
65- 70 F6.3 mag U-g UVEX U-g colour index
72- 77 F6.3 mag g-r UVEX g-r colour index
79- 84 F6.3 mag HeII UVEX HeII magnitude
86- 91 F6.3 mag r-i ?=- UVEX r-i colour index
93- 98 F6.3 mag r-Ha ?=- UVEX r-Hα colour index
100-113 A14 --- Run Run identification
115-127 A13 --- Class Type of object and the 'by eye' most
appropriate spectral type of the spectrum (2)
128-144 A17 --- Fit Result of the spectra fitting (3)
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Note (1): UVEX selection flag (1, 2, 4, 32, 64, 512, 1024 or combinations) and
gives information about how the source was selected:
1 = outlier on the blue side of the main-sequence in the (U-g)
versus (g-r) colour-colour diagram
2 = outlier on the blue side of the main sequence in the g
versus (U-g) colour-magnitude diagram
4 = outlier on the blue side of the main-sequence in the g
versus (g-r) colour magnitude diagram
32 = outlier on the purple side of the main sequence in the (U-g)
versus (g-r) colour-colour diagram
64 = outlier on the non-purple side of the main sequence in the (U-g)
versus (g-r) colour-colour diagram
512 = outlier on the blue side of the main sequence in the g
versus (U-g) colour-magnitude diagram that lies more than
0.4mag away from the main-sequence blue edge
1024 = outlier on the blue side of the main sequence in the g
versus (g-r) colour-magnitude diagram that lies more than
0.4mag away from the main-sequence blue edge
Note (2): Sources which have no good fitting result are labelled as 'Noisy'
Note (3): Parameters separated by slashes (/):
* For white dwarfs: the effective temperature Teff in kK,
and if available the surface gravity logg.
* For He-sdO, sdO, sdB and BHB/MS B-type sources: Teff in kK, logg and
log(n(He)/n(H))
* For F-type MS/BHB sources without He lines: Teff in kK and logg.
* For sources classified as MS/BHB and for most sources labelled as
'Noisy', most appropriate MS spectral type and reddening E(B-V).
* For the Hα emission-line stars, the FWHM and equivalent
width of the Hα line given (in Å=0.1nm).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/46] Sequential number
4- 22 A19 --- UVEX UVEX name, JHHMMSS.ss+DDMMSS.s
24- 28 I5 K Teff1 ? Effective temperature from first method,
fits Teff and logg
30- 33 I4 K e_Teff1 ? rms uncertainty on Teff1
34 A1 --- --- [/]
35- 38 F4.2 [cm/s2] logg1 ? Surface gravity from first method,
fits Teff and logg
40- 43 F4.2 [cm/s2] e_logg1 ? rms uncertainty on logg1
45- 49 I5 K Teff2 Effective temperature from second method,
fits Teff and E(B-V)
50 A1 --- --- [/]
51- 53 F3.1 mag E(B-V)2 Colour excess from second method,
fits Teff and E(B-V)
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [UVEX]
5- 23 A19 --- UVEX UVEX name, JHHMMSS.ss+DDMMSS.s
25- 30 F6.3 mag gmag g magnitude
32- 53 A22 --- Class Classification/fitting (1)
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Note (1): Best fit:
* for the He-sdO, sdO, sdB and B-type BHB/MS sources:
Teff in kK, logg and log (n(He)/n(H)).
* For the MS/BHB sources without He lines, Teff in kK and logg
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 08-Apr-2013