J/MNRAS/488/1282 Variable dust emission by WC type Wolf-Rayets (Williams, 2019)
Variable dust emission by WC type Wolf-Rayet stars observed in the NEOWISE-R
survey.
Williams P.M.
<Mon. Not. R. Astron. Soc., 488, 1282-1300 (2019)>
=2019MNRAS.488.1282W 2019MNRAS.488.1282W (SIMBAD/NED BibCode)
ADC_Keywords: Stars, Wolf-Rayet ; Photometry, infrared ; Extinction ;
Stars, variable ; Milky Way ; Magellanic Clouds
Keywords: stars: winds, outflows - stars: Wolf-Rayet
Abstract:
Photometry at 3.4 and 4.6µm of 128 Population I WC type Wolf-Rayet
stars in the Galaxy and 12 in the Large Magellanic Cloud (LMC)
observed in the WISE NEOWISE-R survey was searched for evidence of
circumstellar dust emission and its variation. Infrared spectral
energy distributions (SEDs) were assembled, making use of archival r,
i, Z, and Y photometry to determine reddening and stellar wind levels
for the WC stars found in recent IR surveys and lacking optical
photometry. From their SEDs, 10 apparently non-variable stars were
newly identified as dust makers, including three, WR 102-22, WR
110-10, and WR 124-10, having subtype earlier than WC8-9, the first
such stars to show this phenomenon. The 11 stars found to show
variable dust emission include six new episodic dust makers, WR 47c,
WR 75-11, WR 91-1, WR 122-14, and WR 125-1 in the Galaxy and HD 38030
in the LMC. Of previously known dust makers, NEOWISE-R photometry of
WR 19 captured its rise to maximum in 2018 confirming the 10.1-yr
period, that of WR 125 the beginning of a new episode of dust
formation suggesting a period near 28.3yr. while that of HD 36402
covered almost a whole period and forced revision of it to 5.1yr.
Description:
The principal data set on which this study is based is the 2019 data
Release of the NEOWISE-R survey. The wavelengths of the W1 and W2
bands, 3.4 and 4.6µm, are well placed for observing Tg∼1000-K
circumstellar dust emission. The instrument has the sensitivity to
cover the fainter and heavily reddened WR stars found in recent IR
surveys, e.g. Mauerhan, Van Dyk & Morris (2009PASP..121..591M 2009PASP..121..591M), Shara
et al. (2009AJ....138..402S 2009AJ....138..402S) but, on the other hand, most of the WR
dust emitters found in the earlier studies are too bright for
NEOWISE-R, so there is little overlap with the earlier studies.
The observations were taken between late 2013 and late 2018. The
cadence of the observations makes them most useful for studying
variations over short (∼1-2d) and long (∼1-5yr) time-scales, of which
the latter are of interest for the present investigation.
The NEOWISE-R Single Exposure Source Data base in the NASA/IPAC
Infrared Science Archive (IRSA) data were searched at the positions of
all WC stars in V1.22
(http://pacrowther.staff.shef.ac.uk/WRcat/index.php, dated 2019 March)
of the Galactic WR Catalogue (Rosslowe & Crowther
2015MNRAS.447.2322R 2015MNRAS.447.2322R).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 75 128 Galactic program stars
table2.dat 60 12 Large Magellanic Cloud program stars
table3.dat 38 10 Persistent, apparently constant, dust makers,
newly identified as such in this study
table4.dat 44 10 Galactic WC stars newly identified as variable
dust makers
table5.dat 42 13 Photometric history of WR 19 from WISE
observations
table6.dat 38 19 IR photometric history of WR 46-7
table7.dat 41 14 Mid-IR photometric history of WR 47c
table8.dat 40 13 Mid-IR photometric history of WR 60-4
table9.dat 49 12 WISE photometric history of WR 75aa
table10.dat 49 13 Mid-IR photometric history of WR 75d
table11.dat 41 14 IR photometric history of WR 75-11
table12.dat 49 13 Mid-IR photometric history of WR 77t
table13.dat 40 14 Mid-IR photometric history of WR 91-1
table14.dat 41 13 Mid-IR photometric history of WR 122-14
table15.dat 38 11 WISE photometric history of WR 125
table16.dat 47 15 IR photometric history of WR 125-1
table17.dat 38 12 WISE photometric history of HD 36402
table18.dat 42 15 Mid-IR photometric history of HD 38030
table19.dat 103 21 Properties of WR stars showing variation in
their dust emission, including orbital
information or indications of possible binarity
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- WR Running number from the Galactic Wolf-Rayet
catalogue (Rosslowe & Crowther
2015MNRAS.447.2322R 2015MNRAS.447.2322R)
8- 32 A25 --- Name Star name
34- 41 A8 --- SpType Wolf-Rayet spectral type (1)
43- 47 F5.2 mag W1mag NEOWISE-R W1 (3.4um) band magnitude
49- 52 F4.2 mag e_W1mag Error on W1mag
54- 57 F4.1 --- RW1mag Long-term variability metric R for W1mag (G1)
59- 63 F5.2 mag W2mag NEOWISE-R W2 (4.6um) band magnitude
65- 68 F4.2 mag e_W2mag Error on W2mag
70- 73 F4.1 --- RW2mag Long-term variability metric R for W2mag (G1)
75 A1 --- f_Name [*dw] Flag on Name (2)
--------------------------------------------------------------------------------
Note (1): The spectral types, including 'd' to mark dust makers, are from the
WR catalogue, as updated by Rosslowe & Crowther (2015MNRAS.447.2322R 2015MNRAS.447.2322R)
where appropriate
Note (2): Flag as follows:
* = Star discussed individually in Section 4
d = Star found or confirmed to be dust marker in this study
w = Possible dust maker found here to have stellar-wind SEDs
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- BAT99 BAT99 identifier (NNN) (Breysacher, Azzopardi
& Testor 1999A&AS..137..117B 1999A&AS..137..117B)
5- 12 A8 --- Name Star name
14- 26 A13 --- SpType Wolf-Rayet spectral type
28- 32 F5.2 mag W1mag NEOWISE-R W1 (3.4um) band magnitude
34- 37 F4.2 mag e_W1mag Error on W1mag
39- 42 F4.1 --- RW1mag Long-term variability metric R for W1mag (G1)
44- 48 F5.2 mag W2mag NEOWISE-R W2 (4.6um) band magnitude
50- 53 F4.2 mag e_W2mag Error on W2mag
55- 58 F4.1 --- RW2mag Long-term variability metric R for W2mag (G1)
60 A1 --- f_Name Flag on Name (1)
--------------------------------------------------------------------------------
Note (1): Flag as follows:
* = Star discussed individually in Section 4
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- WR Running number from the Galactic Wolf-Rayet
catalogue (Rosslowe & Crowther
2015MNRAS.447.2322R 2015MNRAS.447.2322R)
8- 10 A3 --- SpType Wolf-Rayet spectral type (1)
12- 15 F4.1 --- D/W Ratio of dust to wind emission at 3.4um
17- 20 I4 --- Tdust Dust temperature at the inner edge of the
cloud (2)
22- 23 I2 --- e_Tdust Error on Tdust
25- 28 F4.2 mag rms Quality of the fit to the data
30- 33 F4.1 mag Av Visual extinction
35- 38 A4 --- Bands Photometric bands used for determination of
AV
--------------------------------------------------------------------------------
Note (1): The spectral types are from the Galactic WR Catalogue (Rosslowe &
Crowther 2015MNRAS.447.2322R 2015MNRAS.447.2322R) and should now have 'd' appended
Note (2): Isothermal in the case of WR 111-10
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- WR Running number from the Galactic Wolf-Rayet
catalogue (Rosslowe & Crowther
2015MNRAS.447.2322R 2015MNRAS.447.2322R)
8- 12 A5 --- SpType Wolf-Rayet spectral type
14- 17 F4.2 mag DW1 Amplitude of variability ΔW1 (1)
19- 20 A2 --- l_Av [~<] Limit flag on Av
22- 25 F4.1 mag Av Visual extinction
27- 28 A2 --- l_D/W [≳] Limit flag on D/W
30- 32 F3.1 --- D/W Ratio of dust to wind emission at 3.4um
34- 40 F7.2 yr Epoch Epoch at which D/W was measured
42- 44 A3 --- Var Type of variability (2)
--------------------------------------------------------------------------------
Note (1): The amplitudes ΔW1 are based on all the WISE data except for
WR 77t, which is bright enough for saturation to affect the NEOWISE-R
data, so its ΔW1 comes from the All-Sky and 3-Band Cryo
observations.
Note (2): Type of variability as follows:
Ep = Episodic variation, dust is formed for only part of the time
Ep? = Probable episodic variation
V = Variable, dust forms persistently but at a variable rate
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.2 yr Date Date of observation
9- 12 F4.2 --- Phase Orbital phase
14- 17 F4.2 mag W1mag W1 (3.4um) band magnitude
19- 22 F4.2 mag e_W1mag Error on W1mag
24- 27 F4.2 mag W2mag W2 (4.6um) band magnitude
29- 32 F4.2 mag e_W2mag Error on W2mag
34- 42 A9 --- Survey Survey used for observations (All-Sky,
Post Cryo or NEOWISE-R)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.2 yr Date Date of observation
9- 13 F5.2 mag Ksmag ? Ks-band magnitude
15- 18 F4.2 mag W1mag ? W1 (3.4um) band magnitude (G2)
20- 23 F4.2 mag W2mag ? W2 (4.6um) band magnitude (G2)
25- 28 F4.2 mag W3mag ? W3 (12um) band magnitude
30- 38 A9 --- Survey Survey used for observations (DENIS, 2MASS,
GLIMPSE, All-Sky, Post-Cryo, VVV or
NEOWISE-R)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table[78].dat table1[13457].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.2 yr Date Date of observation
9- 13 F5.2 mag W1mag ? W1 (3.4um) band magnitude (G2)
15- 18 F4.2 mag e_W1mag ? Error on W1mag
20- 23 F4.2 mag W2mag W2 (4.6um) band magnitude (G2)
25- 28 F4.2 mag e_W2mag Error on W2mag
30- 41 A12 --- Survey Survey used for observations (GLIMPSE,
All-Sky, Deep GLIMPSE, 3-Band Cryo or
NEOWISE-R)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table9.dat table10.dat table12.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.2 yr Date Date of observation
9- 12 F4.2 mag W1mag W1 (3.4um) band magnitude
14- 17 F4.2 mag e_W1mag Error on W1mag
19- 22 F4.2 mag W2mag W2 (4.6um) band magnitude
24- 27 F4.2 mag e_W2mag Error on W2mag
29- 32 F4.2 mag W3mag ? W3 (12um) band magnitude
34- 37 F4.2 mag e_W3mag ? Error on W3mag
39- 49 A11 --- Survey Survey used for observations (GLIMPSE,
All-Sky, 3-Band Cryo or NEOWISE-R)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table16.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.2 yr Date Date of observation
9- 12 F4.2 mag Ksmag ? Ks-band magnitude
14- 17 F4.2 mag e_Ksmag ? Error on Ksmag
19- 22 F4.2 mag W1mag ? W1 (3.4um) band magnitude (G2)
24- 27 F4.2 mag e_W1mag ? Error on W1mag
29- 32 F4.2 mag W2mag ? W2 (4.6um) band magnitude (G2)
34- 37 F4.2 mag e_W2mag ? Error on W2mag
39- 47 A9 --- Survey Survey used for observations (2MASS, GLIMPSE,
UKIDSS, All-Sky, Post-Cryo or NEOWISE-R)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table18.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.2 yr Date Date of observation
9- 13 F5.2 mag W1mag W1 (3.4um) band magnitude (1)
15- 18 F4.2 mag e_W1mag Error on W1mag
20- 24 F5.2 mag W2mag W2 (4.6um) band magnitude (1)
26- 29 F4.2 mag e_W2mag Error on W2mag
31- 42 A12 --- Survey Survey used for observations (SAGE Epoch 1,
SAGE Epoch 2, All-Sky, Post-Cryo or
NEOWISE-R)
--------------------------------------------------------------------------------
Note (1): SAGE (Bonanos et al. 2009AJ....138.1003B 2009AJ....138.1003B, Cat. J/AJ/138/1003) survey
has 3.6um and 4.5um magnitudes consistent with the WISE data
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table19.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Star name
11- 21 A11 --- SpType Spectral type
23- 44 A22 --- Binary Orbital information and possible binarity
46- 48 A3 --- r_SpType ? References (4)
50- 51 A2 --- Var Type of variability (1)
53- 80 A28 --- Tmax Dates of IR maxima
82 A1 --- l_DeltaL Limit flag on DeltaL
84- 87 F4.2 mag DeltaL ? Amplitude (2)
89 A1 --- l_Period [~>] Limit flag on Period
91- 95 F5.2 yr Period ? Period of the dust emission
97 A1 --- f_Period Flag on Period (3)
99-103 A5 --- r_Tmax References (4)
--------------------------------------------------------------------------------
Note (1): Type of variability as follows:
Ep = Episodic dust makers
V = Persistent variable dust makers
Note (2): The amplitudes ΔL are those in W1 for the variables found in
this study and in L' for the previously known variables.
Note (3): Flag as follows:
* = irregular period
? = uncertain period
Note (4): References as follows:
1 = Williams et al. (2009MNRAS.395.2221W 2009MNRAS.395.2221W)
2 = Crowther, De Marco & Barlow (1998MNRAS.296..367C 1998MNRAS.296..367C)
3 = Veen et al. (1998A&A...339L..45V 1998A&A...339L..45V)
4 = Zhekov et al. (2014MNRAS.445.1663Z 2014MNRAS.445.1663Z)
5 = Marchenko & Moffat (2007ASPC..367..213M 2007ASPC..367..213M)
6 = Williams et al. (2012MNRAS.420.2526W 2012MNRAS.420.2526W)
7 = Williams & van der Hucht (2015wrs..conf..275W)
8 = Niemela (1995IAUS..163..223N 1995IAUS..163..223N)
9 = Williams et al. (2013MNRAS.429..494W 2013MNRAS.429..494W)
10 = Monnier, Tuthill & Danchi (1999ApJ...525L..97M 1999ApJ...525L..97M)
11 = Williams et al. (2003IAUS..212..115W 2003IAUS..212..115W)
12 = Cohen & Kuhi (1976PASP...88..535C 1976PASP...88..535C)
13 = Williams et al. (1994MNRAS.266..247W 1994MNRAS.266..247W)
14 = Lefevre et al. (2005MNRAS.360..141L 2005MNRAS.360..141L)
15 = Williams et al. (2001MNRAS.324..156W 2001MNRAS.324..156W)
16 = Fahed et al. (2011MNRAS.418....2F 2011MNRAS.418....2F); Monnier et al. (2011ApJ...742L...1M 2011ApJ...742L...1M)
17 = Williams et al. (1990MNRAS.243..662W 1990MNRAS.243..662W, 2009MNRAS.395.1749W 2009MNRAS.395.1749W)
18 = Taranova & Shenavrin (2011AstL...37...30T 2011AstL...37...30T, Cat. J/PAZh/37/34)
19 = Moffat et al. (1990ApJ...348..232M 1990ApJ...348..232M)
20 = Williams et al. (2013MNRAS.431.1160W 2013MNRAS.431.1160W)
--------------------------------------------------------------------------------
Global Notes:
Note (G1): This is the ratio, R, of the intervisit (semestrial) dispersion to
the mean intravisit (orbital) dispersion
Note (G2): The magnitudes tabulated under W1 and W2 for the GLIMPSE observations
are 3.6um and 4.5um and the date comes from the Spitzer Heritage
Archive
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 29-Nov-2022