J/ApJ/887/82 Galactic carbon stars infrared spectroscopy (Kraemer+, 2019)
Stellar pulsation and the production of dust and molecules in Galactic carbon
stars.
Kraemer K.E., Sloan G.C., Keller L.D., McDonald I., Zijlstra A.A.,
Groenewegen M.A.T.
<Astrophys. J., 887, 82 (2019)>
=2019ApJ...887...82K 2019ApJ...887...82K
ADC_Keywords: Stars, carbon; Spectra, infrared; Colors
Keywords: Carbon stars ; Circumstellar matter ; Long period variable stars ;
Spectroscopy
Abstract:
New infrared spectra of 33 Galactic carbon stars from FORCAST on SOFIA
reveal strong connections between stellar pulsations and the dust and
molecular chemistry in their circumstellar shells. A sharp boundary in
overall dust content, which predominantly measures the amount of
amorphous carbon, separates the semiregular and Mira variables, with
the semiregulars showing little dust in their spectra and the Miras
showing more. In semiregulars, the contribution from SiC dust
increases rapidly as the overall dust content grows, but in Miras, the
SiC dust feature grows weaker as more dust is added. A similar
dichotomy is found with the absorption band from CS at ∼7.3µm,
which is generally limited to semiregular variables. Observationally,
these differences make it straightforward to distinguish semiregular
and Mira variables spectroscopically without the need for long-term
photometric observations or knowledge of their distances. The rapid
onset of strong SiC emission in Galactic carbon stars in semiregular
variables points to a different dust-condensation process before
strong pulsations take over. The break in the production of amorphous
carbon between semiregulars and Miras seen in the Galactic sample is
also evident in Magellanic carbon stars, linking strong pulsations in
carbon stars to the strong mass-loss rates which will end their lives
as stars across a wide range of metallicities.
Description:
The Stratospheric Observatory for Infrared Astronomy (SOFIA) observed
the 33 Galactic carbon stars of our sample (see Table 1) in service
mode over the course of three cycles, Cycle 1 (2013, 4 stars,
PlanID=010041), Cycle 3 (2015, 10 stars, 03_0104), and Cycle 4
(2016, 21 stars, 04_0129).
We used the two low-resolution grism settings in FORCAST, G063 and
G111, to obtain spectra over the wavelength ranges 4.9-7.8 and
8.3-13.8um, respectively with a spectral resolution of R∼120.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 65 35 SOFIA/FORCAST targets
table2.dat 56 33 Dust properties
table5.dat 105 42 Revised feature strengths - SWS sample
(Sloan+, 2016, J/ApJ/826/44/table6)
table6.dat 105 184 Revised feature strengths - IRS sample
(Sloan+, 2016, J/ApJ/826/44/cstars)
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See also:
B/gcvs : General Catalogue of Variable Stars (Samus+, 2007-2017)
III/227 : General Catalog of galactic Carbon stars, 3d Ed. (Alksnis+ 2001)
J/AJ/132/2268 : SAGE calibration stars (Meixner+, 2006)
J/MNRAS/369/751 : Near-infrared photometry of carbon stars (Whitelock+, 2006)
J/MNRAS/376/313 : Carbon star in Magellanic Cloud (Groenewegen+, 2007)
J/AcA/59/239 : VI LCs of LMC long-period variables (Soszynski+, 2009)
J/AJ/142/103 : Cool evolved stars in SAGE-SMC and SAGE-LMC (Boyer+, 2011)
J/AcA/61/217 : VI LCs of SMC long-period variables (Soszynski+, 2011)
J/A+A/566/A95 : C-rich giants synthetic spectrophotom. IV (Eriksson+, 2014)
J/MNRAS/449/639 : VMC survey. XIV. SFR in SMC (Rubele+, 2015)
J/ApJ/826/44 : Spitzer/IRS obs. of Magellanic carbon stars (Sloan+, 2016)
J/A+A/609/A114 : Local Group AGB stars & red supergiants (Groenewegen+, 2018)
J/A+A/629/A94 : CO spectra of 49 semi-regular variables (Diaz-Luis+, 2019)
J/A+A/628/A62 : Spectra of 25 carbon star envelopes (Massalkhi+, 2019)
J/A+A/622/A120 : Mass loss from Miras with and without Tc (Uttenthaler, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Star name
12 A1 --- f_Name Flag on Name (1)
14- 15 I2 h RAh Hour of right ascension (J2000)
17- 18 I2 min RAm Minute of right ascension (J2000)
20- 24 F5.2 s RAs Second of right ascension (J2000)
26 A1 --- DE- Sign of declination (J2000)
27- 28 I2 deg DEd Degree of declination (J2000)
30- 31 I2 arcmin DEm Arcminute of declination (J2000)
33- 36 F4.1 arcsec DEs Arcsecond of declination (J2000)
38- 48 A11 "Y/M/D" Date Date of observation (UT)
50- 52 I3 d Per Period
53 A1 --- u_Per [:] Uncertainty flag on Per
55- 59 I5 Jy F12 [44/47530] Fv at 12um
61 I1 --- Group [1/3] Group (G1)
63- 65 A3 --- r_Per Reference on Per (2)
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Note (1): Flag as follows:
a = Observations problematic and not included in analysis.
Note (2): Reference as follows:
J90 = Jones+ 1990ApJS...74..785J 1990ApJS...74..785J
S98 = Sloan+ 1998AJ....115..809S 1998AJ....115..809S and Kholopov+ 1992BICDS..40...15K 1992BICDS..40...15K
N00 = Nakashima+ 2000PASJ...52..275N 2000PASJ...52..275N
W06 = Whitelock+ 2006, J/MNRAS/369/751
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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 I1 --- Group [1/3] Group (G1)
3- 12 A10 --- Name Star name
14- 18 F5.3 mag 6-9um [0.069/1.6] The ([6]-[9]) color index
20- 24 F5.3 mag e_6-9um [0.002/0.015] 6-9um uncertainty
26- 31 F6.3 --- FSiC [-0.021/0.4] SiC flux relative to the continuum
33- 37 F5.3 --- e_FSiC [0.002/0.02] FSiC uncertainty
39- 43 F5.2 um lamC [11.19/11.98] λC value (1)
45- 48 F4.2 um e_lamC [0.01/0.2] LamC uncertainty
50- 54 F5.2 Msun/yr logDPR [-8.8/-6.4] Log of the dust production rate
56 I1 --- Class [1/5] CE class from Sloan+, 2016, J/ApJ/826/44
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Note (1): The parameter λC is the wavelength at which half of the
flux in the SiC feature is to the red and half to the blue.
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Byte-by-byte Description of file: table[56].dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Name Target identifier
23- 28 F6.3 --- FSiC1 [-0.18/2.9] SiC flux relative to the continuum
- This work
34- 39 F6.3 --- e_FSiC1 [0/0.09] Uncertainty in FSiC1
45- 50 F6.3 --- FSiC2 [-0.16/3.1] SiC flux relative to the continuum
- S16 (Sloan+, 2016, J/ApJ/826/44)
56- 61 F6.3 --- e_FSiC2 [0/0.09] Uncertainty in FSiC2
67- 72 F6.3 mag Color1 [-0.15/0.5] The ([6]-[9]) color - This work
78- 83 F6.3 mag e_Color1 [0.001/0.05] Uncertainty in Color1
89- 94 F6.3 mag Color2 [-0.16/0.6] The ([6]-[9]) color - S16
100-105 F6.3 mag e_Color2 [0.001/0.04] Uncertainty in Color2
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Global notes:
Note (G1): Group as follows:
1 = Semiregular on the first overtone (SRb) variables with Fv(12um)>40Jy
2 = Mira variables with 400d<Per<500d and Fv>60Jy
3 = Miras with Per>550d and Fv>150Jy
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 11-May-2021