J/ApJ/935/175 Parameters of OB stars with IR excess (Deng+, 2022)
Infrared Excess of a Large OB Star Sample.
Deng D., Sun Y., Wang T., Wang Y., Jiang B.
<Astrophys. J., 935, 175 (2022)>
=2022ApJ...935..175D 2022ApJ...935..175D
ADC_Keywords: Stars, OB; Photometry, infrared; Optical
Keywords: OB stars ; Infrared excess ; Extinction ; Circumstellar matter
; Circumstellar dust
Abstract:
The infrared (IR) excess from OB stars is commonly considered to be a
contribution from ionized stellar wind or circumstellar dust. With the
newly published Large Sky Area Multi-Object Fiber Spectroscopy
Telescope (LAMOST)-OB catalog and Galactic O-Star Spectroscopic Survey
data, this work steps further on understanding the IR excess of OB
stars. Based on a forward-modeling approach comparing the spectral
slope of observational spectral energy distributions and photospheric
models, 1147 stars are found to have IR excess out of 7818 stars with
good-quality photometric data. After removing the objects in the
sightline of dark clouds, 532(∼7%) B-type stars and 118(∼23%) O-type
stars are identified to be true OB stars with circumstellar IR excess
emission. The ionized stellar wind model and the circumstellar dust
model are adopted to explain the IR excess, and Bayes factors are
computed to quantitatively compare the two. It is shown that the IR
excess can be accounted for by the stellar wind for about 65% cases,
of which 33% by free-free emission and 32% by synchrotron radiation.
Other 30% sources could have and 4% should have a dust component or
other mechanisms to explain the sharp increase in flux at
λ>10µm. The parameters of the dust model indicate a
large-scale circumstellar halo structure, which implies the origin of
the dust from the birthplace of the OB stars. A statistical study
suggests that the proportion with IR excess in OB stars increases with
the stellar effective temperature and luminosity, and that there is no
systematic change in the mechanism for IR emission with stellar
parameters.
Description:
The optical photometry from the Gaia Early Data Release 3, Panoramic
Survey Telescope And Rapid Response System (Pan-STARRS) 1 DR2, and
American Association of Variable Star Observers Photometric All-Sky
Survey (APASS) DR9 surveys were adopted.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 142 625 The parameters of the stars with IR excess
from LAMOST
table3.dat 139 25 The parameters of the stars with IR excess
from GOSSS
--------------------------------------------------------------------------------
See also:
II/297 : AKARI/IRC mid-IR all-sky Survey (ISAS/JAXA, 2010)
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)
VI/39 : Model Atmospheres (Kurucz, 1979)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
VII/244 : Atlas and Catalog of Dark Clouds (Dobashi+, 2005)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
VIII/106 : Herschel/PACS Point Source Catalogs (Herschel team, 2017)
J/ApJ/663/320 : IR-through-UV extinction curve (Fitzpatrick+, 2007)
J/A+A/481/345 : SED evolution massive young stellar objects (Molinari+, 2008)
J/PASJ/63/S1 : Atlas & catalog of dark clouds based on 2MASS (Dobashi+, 2011)
J/ApJS/224/4 : GOSSS III. 142 additional Otype systems (Maiz Apellaniz+, 2016)
J/A+A/620/A32 : IRS spectra of 22 O7-B5 I-V stars (Siebenmorgen+, 2018)
J/ApJ/852/78 : JHKs, WISE and Spitzer data of Galactic Cepheids (Wang+, 2018)
J/ApJS/241/32 : OB stars from the LAMOST DR5 spectra (Liu+, 2019)
J/ApJS/257/54 : Early-type star param. from LAMOST LRS & MRS (Guo+, 2021)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.4 deg RAdeg [0/360] Right ascension (J2000)
10- 16 F7.4 deg DEdeg [-7/66] Declination (J2000)
18- 22 I5 K Teff [10149/57691] Effective temperature
24- 27 F4.2 [cm/s2] logg [3.51/6.15] Surface gravity, log
29- 33 F5.2 mag E(B-V) [-0.15/2.61] Color excess of (B-V) (1)
35- 42 A8 Lsun Lum Luminosity
44- 51 A8 Lsun e_Lum Uncertainty on Luminosity
53- 60 A8 Rsun Rad Stellar Radius
62- 69 A8 Rsun e_Rad Uncertainty on Stellar Radius
71- 71 A1 --- Best Best model (2)
73- 80 A8 --- BF ? Bayes Factor (3)
82- 86 F5.1 --- alpha [-10.0/2.0]? Spectral index from the best
stellar wind model
88- 92 F5.1 --- b_alpha [-10.0/1.9]? Lower limit of the 68%
confidential interval of alpha
94- 97 F4.1 --- B_alpha [-7.8/2.0]? Upper limit of the 68%
confidential interval of alpha
99-107 A9 --- tau ? Optical depth at 550nm from the best DUSTY
model
109-117 A9 --- b_tau ? Lower limit of the 68% confidential
interval of tau
119-127 A9 --- B_tau ? Upper limit of the 68% confidential
interval of tau
129-132 I4 K Tdinner [300/1400]? Dust inner temperature from the
best DUSTY model
134-137 I4 K b_Tdinner [300/1350]? Lower limit of the 68%
confidential interval of Tdinner
139-142 I4 K B_Tdinner [350/1400]? Upper limit of the 68%
confidential interval of Tdinner
--------------------------------------------------------------------------------
Note (1): Color excess calculated accordingly by the intrinsic color defined
by Deng+ 2020AJ....159..208D 2020AJ....159..208D
Note (2): Best model --
'S' or 'F' = stellar wind model with synchrotron radiation or
free-free emission;
'B' for the case both stellar wind model and wind-dust model work;
'D' for wind-dust model;
'U' for the stars that none of the model could work;
'X' for the case that excluded due to lack of observations.
Note (3): Bayes Factor computed as the goodness of stellar wind model over
wind-dust model. Larger BF value indicates the SED favors more the
stellar wind model.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- Name Source name
15- 19 I5 K Teff [10000/50000] Effective temperature
21- 24 F4.2 [cm/s2] logg [3.5/5.0] Surface gravity, log
26- 29 F4.2 mag E(B-V) [0.31/1.45] Color excess of (B-V) (1)
31- 38 A8 Lsun Lum Luminosity
40- 47 A8 Lsun e_Lum Uncertainty on Luminosity
49- 56 A8 Rsun Rad Stellar Radius
58- 65 A8 Rsun e_Rad Uncertainty on Stellar Radius
67- 67 A1 --- Best Best model (2)
69- 77 A9 --- BF ? Bayes Factor (3)
79- 83 F5.1 --- alpha [-10.0/2.0]? Spectral index from the best
stellar wind model
85- 89 F5.1 --- b_alpha [-10.0/1.9]? Lower limit of the 68%
confidential interval of alpha
91- 94 F4.1 --- B_alpha [-7.5/2.0]? Upper limit of the 68%
confidential interval of alpha
96-104 A9 --- tau ? Optical depth at 550nm from the best DUSTY
model
106-114 A9 --- b_tau ? Lower limit of the 68% confidential
interval of tau
116-124 A9 --- B_tau ? Upper limit of the 68% confidential
interval of tau
126-129 I4 K Tdinner [300/1400]? Dust inner temperature from the
best DUSTY model
131-134 I4 K b_Tdinner [300/1200]? Lower limit of the 68%
confidential interval of Tdinner
136-139 I4 K B_Tdinner [350/1400]? Upper limit of the 68%
confidential interval of Tdinner
--------------------------------------------------------------------------------
Note (1): Color excess calculated accordingly by the intrinsic color defined
by Deng+, 2020AJ....159..208D 2020AJ....159..208D
Note (2): Best model --
'S' or `F' = stellar wind model with synchrotron radiation or
free-free emission;
'B' for the case both stellar wind model and wind-dust model work;
'D' for wind-dust model;
'U' for the stars that none of the model could work;
'X' for the case that excluded due to lack of observations.
Note (3): Bayes Factor computed as the goodness of stellar wind model over
wind-dust model. Larger BF value indicates the SED favors more the
stellar wind model.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 10-Jun-2024