J/ApJ/954/123 Hot massive-star X-ray sp. from Chandra HETGS (Pradhan+, 2023)
Survey of X-rays from massive stars observed at high spectral resolution with
Chandra.
Pradhan P., Huenemoerder D.P., Ignace R., Nichols J.S., Pollock A.M.T.
<Astrophys. J., 954, 123 (2023)>
=2023ApJ...954..123P 2023ApJ...954..123P
ADC_Keywords: X-ray sources; Stars, Wolf-Rayet; Stars, O; Stars, B-type;
Stars, double and multiple; Spectroscopy
Keywords: High resolution spectroscopy ; Massive stars ; X-ray stars
Abstract:
Identifying trends between observational data and the range of
physical parameters of massive stars is a critical step to the
still-elusive full understanding of the source, structure, and
evolution of X-ray emission from the stellar winds, requiring a
substantial sample size and systematic analysis methods. As of 2022,
the Chandra data archive contains 37 high-resolution spectra of O, B,
and WR stars, observed with the Chandra/HETGS, and of sufficient
quality to fit the continua and emission-line profiles. Using a
systematic approach to the data analysis, we explore morphological
trends in the line profiles (i.e., O, Ne, Mg, and Si) and find that
the centroid offsets of resolved lines versus wavelength can be
separated in three empirically defined groups based on the amount of
line broadening and centroid offset. Using Fe XVII (15.01, 17.05Å)
and Ne Xα (12.13Å) lines, which are prevalent among the
sample stars, we find a well-correlated linear trend of increasing
Full Width Half Maximum with faster wind terminal velocity. The
H-like/He-like total line flux ratio for strong lines displays
different trends with spectral class depending on ion species. Some of
the sources in our sample have peculiar properties (e.g., magnetic and
γ Cas-analog stars) and we find that these sources stand out as
outliers from more regular trends. Finally, our spectral analysis is
presented summarily in terms of X-ray spectral energy distributions in
specific luminosity for each source, including tables of line
identifications and fluxes.
Description:
Data for this project were taken from archival Chandra High Energy
Transmission Grating Spectrometer (HETGS) observations. The HETGS
covers the band from FeXXV (1.85Å) to NVII (24.78Å) with
resolving powers of up to about 1000 and an effective area of up to
about 150cm2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 432 37 The list of sources
table5.dat 80 863 Line measurements
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2014)
III/23 : MK Classification for OB Stars (Lesh 1968)
I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007)
III/274 : Galactic O-Star Spectroscopic Survey (GOSSS) (Sota+, 2014)
I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)
J/ApJS/93/211 : IUE survey of H I Lyα absorption. I. (Diplas+ 1994)
J/ApJS/169/353 : Chandra sources in M17 (Broos+, 2007)
J/AJ/138/33 : VLT JHKs imaging of RCW 38 (Derose+, 2009)
J/A+A/501/297 : Effective temperatures of B Supergiants (Zorec+, 2009)
J/AJ/141/129 : Chandra Transmission Grating Data Cat. (Huenemoerder+, 2011)
J/other/Sci/337.444 : RV curves of Galactic massive O stars (Sana+, 2012)
J/ApJS/224/4 : GOSSS III. Additional O-type systems (Maiz Apellaniz+, 2016)
J/A+A/594/A82 : XMM sources in IC 1805 (Rauw+, 2016)
J/AJ/152/213 : Interferometry & sp. of sigma Orionis (Schaefer+, 2016)
J/MNRAS/456/2 : MiMeS survey of magnetism in massive stars (Wade+, 2016)
J/A+A/619/A148 : Hot stars observed by XMM-Newton. II. (Naze+, 2018)
J/A+A/620/A89 : X-ray catalog of Galactic O stars (Nebot Gomez-Moran+, 2018)
J/A+A/626/A20 : MONOS. I. Spectral classifications (Maiz Apellaniz+, 2019)
J/A+A/643/A138 : Possible runaway stars list (Maiz Apellaniz+, 2020)
J/MNRAS/493/1512 : Galactic Wolf-Rayet stars with Gaia DR2 I (Rate+, 2020)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq [1/37] Running sequence number
4- 17 A14 --- Name Name of the source
19- 23 F5.2 10-17W/m2 Flux [0.1/17.65] Observed flux
in 1011erg/cm2/s units
25- 31 F7.2 ct/ks CRate [8.05/3000] Count rate
33- 36 I4 ks Exp [50/2035] Exposure time
38- 40 F3.1 % Err [0.1/2.5] Percentage uncertainty
42- 43 I2 --- Nobs [1/68] Number of observations
45-432 A388 --- ObsID List of observation identifier(s) used
in this work
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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- 14 A14 --- Name Stellar identifier
17- 28 A12 --- Ion Ion identifier
30- 35 F6.3 0.1nm Wave0 [1.78/24.8] Theoretical line wavelength;
Angstroms
37- 41 I5 km/s Deltav [-1577/1427]? Measured line wavelength
offset from Wave0 (1)
43- 45 I3 km/s e_Deltav [4/523]? Uncertainty in Deltav (1)
47- 50 I4 km/s FWHM [69/3953]? Line Full-Width at
Half-Maximum (1)
52- 55 I4 km/s e_FWHM [11/1144]? Uncertainty in FWHM (1)
57- 62 F6.2 10+5ph/cm2/s Fx [0.02/101] Observed X-ray flux (1)
64- 67 F4.2 10+5ph/cm2/s e_Fx [0/7] Uncertainty in Fx (1)
69- 74 F6.2 10+5ph/cm2/s F0 [0.03/176] X-ray flux corrected for
interstellar absorption (1)
76- 80 F5.2 10+5ph/cm2/s e_F0 [0/92]? Uncertainty in F0 (1)
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Note (1): For those lines where the Gaussian line center or line width were
not determined by the fit, we only provide fluxes. Since the
interstellar absorption term's bounds are systematic uncertainties,
any change (as per the uncertainties on NH listed in Table 2)
would be correlated over all lines for any given star. Hence, we
have not propagated the statistical flux uncertainty with the
systematic absorption uncertainty. We provide the latter to give
some idea of the possible effects of uncertain absorption. The
fractional statistical uncertainties on F0 are equal to those of Fx.
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History:
From electronic version of the journal
Licences: cc-by
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 04-Nov-2025