J/MNRAS/487/1400 Spiral structure as revealed by O and B stars (Chen+, 2019)
The Galactic spiral structure as revealed by O- and early B-type stars.
Chen B.-Q., Huang Y., Hou L.-G., Tian H., Li G.-X., Yuan H.-B., Wang H.-F.,
Wang C., Tian Z.-J., Liu X.-W.
<Mon. Not. R. Astron. Soc., 487, 1400-1409 (2019)>
=2019MNRAS.487.1400C 2019MNRAS.487.1400C (SIMBAD/NED BibCode)
ADC_Keywords: Stars, OB ; Stars, early-type ; Milky Way ; Photometry, G band ;
Photometry, ugriz ; Stars, distances ;
Parallaxes, trigonometric ; Proper motions
Keywords: stars: early-type - Galaxy: disc - Galaxy: structure
Abstract:
We investigate the morphology and kinematics of the Galactic spiral
structure based on a new sample of O- and early B-type stars. We
select 6858 highly confident OB star candidates from the combined data
of the VST Photometric Hα Survey Data Release 2 (VPHAS+ DR2) and
the Gaia Data Release 2 (Gaia DR2). Together with the O-B2 stars from
the literature, we build a sample consisting of 14880 O- and early
B-type stars, all with Gaia parallax uncertainties smaller than 20 per
cent. The new sample, hitherto the largest one of O- and early B-type
stars with robust distance and proper motion estimates, covers the
Galactic plane of distances up to 6kpc from the Sun. The sample allows
us to examine the morphology of the Scutum, Sagittarius, Local, and
Perseus Arms in great detail. The spiral structure of the Milky Way as
traced by O- and early B-type stars shows flocculent patterns.
Accurate structure parameters, as well as the means and dispersions of
the vertical velocity distributions of the individual spiral arms are
presented.
Description:
The 6858 new OB star candidates are selected from the VPHAS+ DR2 and
Gaia DR2 catalogues.
The VPHAS+ Survey (Drew et al. 2014MNRAS.440.2036D 2014MNRAS.440.2036D, Cat.
J/MNRAS/440/2036) collected images in the SDSS u, g, r, i broad bands
and the Hα narrow band using the OmegaCAM imager (Kuijken
2011Msngr.146....8K 2011Msngr.146....8K) on the VLT Survey Telescope (VST). The survey is
designed to cover 2000deg2 of the Galactic plane in the southern
hemisphere of Galactic latitude |b|<5° and Galactic longitude
-150°<l<40°, and a Galactic bulge extension of |b|<10°
near the Galactic centre. The VPHAS+ DR2, released in 2016, contains
PSF and aperture photometry of 319 million point-like sources covering
629deg2 of the planned VPHAS+ footprint.
To exclude contaminations of subluminous and overluminous OB stars and
stars of spectral types B4 and later, we combine the VPHAS+ photometry
with the Gaia DR2 data (Gaia Collaboration et al. 2018A&A...616A...1G 2018A&A...616A...1G,
Cat. I/345). Gaia DR2 provides high precision photometric measurements
of over 1.4 billion sources in G, GBP, and GRP bands. The Gaia G
band covers the entire optical wavelength ranging between 330 and
1050nm. Gaia DR2 also releases high-quality parallax and proper motion
measurements of 1.3 billion sources.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 214 6858 OB-star candidate catalogue selected from the
VPHAS+ DR2
table4.dat 169 8814 O-B2 star catalogue compiled from the literature
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See also :
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
II/341 : VPHAS+ DR2 survey (Drew+, 2016)
J/MNRAS/440/2036 : VPHAS+ survey synthetic colours (Drew+, 2014)
B/mk : Catalogue of Stellar Spectral Classifications
(Skiff, 2009- )
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID [1/6858] Star identifier
6- 14 F9.5 deg RAdeg Right ascension (J2000)
16- 24 F9.5 deg DEdeg Declination (J2000)
26- 30 F5.2 mag umag VPHAS+ u-band magnitude
32- 35 F4.2 mag e_umag Error on umag
37- 41 F5.2 mag gmag VPHAS+ g-band magnitude
43- 46 F4.2 mag e_gmag Error on gmag
48- 52 F5.2 mag rmag VPHAS+ r-band magnitude
54- 57 F4.2 mag e_rmag Error on rmag
59- 64 F6.2 mag imag ? VPHAS+ i-band magnitude
66- 69 F4.2 mag e_imag ? Error on imag
71- 75 F5.2 mag Hamag ? VPHAS+ Hα-band magnitude
77- 80 F4.2 mag e_Hamag ? Error on Hamag
82- 89 F8.5 mag Gmag Gaia DR2 G-band magnitude (G1)
91- 98 F8.6 mag e_Gmag Error on Gmag (G1)
100-107 F8.5 mag BPmag Gaia DR2 BP-band magnitude (G1)
109-116 F8.6 mag e_BPmag Error on BPmag (G1)
118-125 F8.5 mag RPmag Gaia DR2 RP-band magnitude (G1)
127-134 F8.6 mag e_RPmag Error on RPmag (G1)
136-144 F9.4 pc Dist Distance calculated from the Gaia DR2
parallaxes using a Bayesian distance
estimator (G2)
146-151 F6.4 mas plx Parallax (G1)
153-158 F6.4 mas e_plx Error on plx (G1)
160-166 F7.3 mas/yr pmRA Proper motion in right ascension (G1)
168-172 F5.3 mas/yr e_pmRA Error on pmRA (G1)
174-180 F7.3 mas/yr pmDE Proper motion in declination (G1)
182-186 F5.3 mas/yr e_pmDE Error on pmDE (G1)
188-214 A27 --- Refs References (G3)
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right ascension (J2000)
11- 19 F9.5 deg DEdeg Declination (J2000)
21- 28 F8.5 mag Gmag Gaia DR2 G-band magnitude (G1)
30- 37 F8.6 mag e_Gmag ? Error on Gmag (G1)
39- 46 F8.5 mag BPmag Gaia DR2 BP-band magnitude (G1)
48- 55 F8.6 mag e_BPmag ? Error on BPmag (G1)
57- 64 F8.5 mag RPmag Gaia DR2 RP-band magnitude (G1)
66- 73 F8.6 mag e_RPmag ? Error on RPmag (G1)
75- 83 F9.4 pc Dist Distance calculated from the Gaia DR2
parallaxes using a Bayesian distance
estimator (G2)
85- 91 F7.4 mas plx Parallax (G1)
93- 98 F6.4 mas e_plx Error on plx (G1)
100-106 F7.3 mas/yr pmRA Proper motion in right ascension (G1)
108-112 F5.3 mas/yr e_pmRA Error on pmRA (G1)
114-120 F7.3 mas/yr pmDE Proper motion in declination (G1)
122-126 F5.3 mas/yr e_pmDE Error on pmDE (G1)
128-147 A20 --- SpType Spectral type
149-169 A21 --- Refs References (G3)
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Global Notes:
Note (G1): Values from Gaia DR2 (Gaia Collaboration 2018A&A...616A...1G 2018A&A...616A...1G,
Cat. I/345)
Note (G2): Bayesian distance estimator (Maiz Apellaniz 2005ESASP.576..179M 2005ESASP.576..179M;
Bailer-Jones et al. 2018AJ....156...58B 2018AJ....156...58B, Cat. I/347), given by:
p(d|plx)=d2exp[-(plx-plxzp-1/d)2/(2σplx2)]p(d)
where σplx is the parallax uncertainty, plxzp is the global
parallax zeropoint (plxzp=-0.029 from Lindegren et al.
2018A&A...616A...2L 2018A&A...616A...2L) and p(d) is the space density distribution prior
for the Galactic OB stars adopted from Maiz Apellaniz, Alfaro & Sota
(2008arXiv0804.2553M 2008arXiv0804.2553M).
Note (G3): References as follows:
Huang et al. = Huang et al. (in preparation)
Maiz Apellaniz et al. = Maiz Apellaniz et al. (2013msao.confE.198M)
Skiff = Skiff (2014yCat....1.2023S 2014yCat....1.2023S, Cat. B/mk)
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 09-Nov-2022