J/AJ/157/176 X-ray emission from Galactic stellar bow shocks (Binder+, 2019)
Searching for faint X-ray emission from Galactic stellar wind bow shocks.
Binder B.A., Behr P., Povich M.S.
<Astron. J., 157, 176 (2019)>
=2019AJ....157..176B 2019AJ....157..176B (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; X-ray sources ; Stars, OB ; Spectral types ;
Stars, distances
Keywords: circumstellar matter - stars: massive - stars: winds, outflows -
X-rays: ISM
Abstract:
We present a stacking analysis of 2.61 Ms of archival Chandra observations
of stellar wind bow shocks. We place an upper limit on the X-ray luminosity
of infrared-detected bow shocks of <2x1029 erg/s, a more stringent
constraint than has been found in previous archival studies and dedicated
observing campaigns of nearby bow shocks. We compare the X-ray luminosities
and LX/Lbol ratios of bow shock driving stars to those of other
OB stars within the Chandra field of view. Driving stars are, on average,
of later spectral type than the field-of-view OB stars, and we do not
observe any unambiguously high LX/Lbol ratios indicative of magnetic
stars in our sample. We additionally assess the feasibility of detecting
X-rays from stellar wind bow shocks with the proposed Lynx X-ray
Observatory. If the X-ray flux originating from the bow shocks is just
below our Chandra detection limit, the nearest bow shock in our sample
(at ∼0.4 kpc with an absorbing column of ∼1021/cm2) should be
observable with Lynx in exposure times on the order of ∼100 ks.
Description:
We searched the Chandra archive for ACIS observations containing the
position of at least one IR-identified bow shock within 5' of the nominal
aim point. This radius was chosen to ensure reasonably small (~<2") and
symmetric point-spread functions (PSFs) at the position of the bow shock.
The search returned 91 archival observations (containing 60 unique bow
shocks) with a total of 2.61 Ms exposure time.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 50 92 Chandra observations containing stellar bow
shocks
table2.dat 58 61 Bow shocks in the sample
table3.dat 103 40 *X-ray detected OB stars
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Note on table3.dat: Known X-ray binaries were excluded from our sample.
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2014)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/A+A/578/A45 : E-BOSS. II. Catalogue second release (Peri+, 2015)
J/ApJS/227/18 : Candidate stellar bowshock nebulae from MIR (Kobulnicky+, 2016)
J/AJ/154/201 : IR properties of stellar bowshock nebulae (Kobulnicky+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- ObsID [748/20120] Chandra observation identifier
7- 16 A10 "date" Date Observation date
18 A1 --- ACIS [IS] ACIS detector
20- 21 I2 h RAh Hour of Right Ascension (J2000) (1)
23- 24 I2 min RAm Minute of Right Ascension (J2000) (1)
26- 30 F5.2 s RAs Second of Right Ascension (J2000) (1)
32 A1 --- DE- Sign of the Declination (J2000) (1)
33- 34 I2 deg DEd Degree of Declination (J2000) (1)
36- 37 I2 arcmin DEm Arcminute of Declination (J2000) (1)
39- 42 F4.1 arcsec DEs Arcsecond of Declination (J2000) (1)
44- 48 F5.1 ks ExpT [1.3/149.4] Effective exposure time
50 I1 --- Nbow [1/3] Number of bow shocks contained within 5'
of the nominal aim point
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Note (1): Position of nominal aim point.
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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- 18 A18 --- Name Bow shock name
20- 21 I2 h RAh Hour of Right Ascension (J2000)
23- 24 I2 min RAm Minute of Right Ascension (J2000)
26- 29 F4.1 s RAs Second of Right Ascension (J2000)
31 A1 --- DE- Sign of the Declination (J2000)
32- 33 I2 deg DEd Degree of Declination (J2000)
35- 36 I2 arcmin DEm Arcminute of Declination (J2000)
38- 39 I2 arcsec DEs Arcsecond of Declination (J2000)
41- 44 F4.1 arcsec R0 [1.5/40.6] Standoff radius R0
46- 48 I3 deg PA [5/355] Position angle
50- 54 F5.1 ks ExpT [1.3/325.9] X-ray exposure time
56- 58 F3.1 arcmin OAA [0.1/4.9] Off-axis angle (G1)
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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- 2 I2 h RAh Hour of Right Ascension (J2000)
4- 5 I2 min RAm Minute of Right Ascension (J2000)
7- 10 F4.1 s RAs Second of Right Ascension (J2000)
12 A1 --- DE- Sign of the Declination (J2000)
13- 14 I2 deg DEd Degree of Declination (J2000)
16- 17 I2 arcmin DEm Arcminute of Declination (J2000)
19- 22 F4.1 arcsec DEs Arcsecond of Declination (J2000)
24- 46 A23 --- Ctp Stellar counterpart(s)
48- 66 A19 --- SpType Spectral type(s) from SIMBAD
68 A1 --- l_Dist [<] Limit flag on Dist
69- 73 F5.2 kpc Dist [0.41/11.7]? Distance (1)
75- 78 F4.2 kpc e_Dist [0.01/4.9]? Uncertainty in Dist
80- 83 I4 ct Cts [5/3004] Net counts, 0.5-7 keV
85- 89 F5.1 ks ExpT [2.4/140.5] Exposure time
91- 93 F3.1 arcmin OAA [0.1/5] Off-axis angle (G1)
95- 98 F4.1 [10-7W] logLX [29.6/33.2]? Log X-ray luminosity (in erg/s)
100 A1 --- Driv [Y/N] Driving star?
102-103 A2 --- Note Note (2)
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Note (1): Distances were derived using the Gaia second data release (Gaia
Collaboration et al. 2018, Cat. I/345).
Note (2): Note as follows:
M = Multiple ObsIDs;
C = Counterpart confusion;
PM = High proper motion.
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Global notes:
Note (G1): For sources with multiple ObsIDs, only the largest off-axis angle is
reported.
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History:
From electronic version of the journal
* 21-Aug-2019:Insert into VizieR
* 03-Nov-2021: Observation date 2209-02-21 corrected for 2009-02-21
in Table 1
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 24-Jul-2019