J/AJ/147/22 Simultaneous SiO and H2O maser observations. IV. (Kim+, 2014)
Statistical studies based on simultaneous SiO and H2O maser surveys toward
evolved stars.
Kim J., Cho S.-H., Kim S.J.
<Astron. J., 147, 22 (2014)>
=2014AJ....147...22K 2014AJ....147...22K
ADC_Keywords: Stars, masers ; Stars, variable ; Radio lines ; Space velocities
Keywords: circumstellar matter - masers - radio lines: stars - stars: late-type
Abstract:
Based on the simultaneous observational results of SiO and H2O
masers toward 401 evolved stars, we have performed statistical
analyses. We find that the peak and integrated intensities of SiO
masers are stronger than those of H2O masers in both Mira variables
and OH/IR stars at most optical phases. However, the relative
intensity ratios of H2O to SiO masers in OH/IR stars are larger than
those in Mira variables. Moreover, the intensity ratios of H2O to
SiO masers are found to be increased around the optical phases from
0-0.4. The H2O photon luminosities also tend to be more dependent on
the optical phase compared with those of SiO masers. These facts
suggest that H2O masers are more sensitive to expanding the motion
of circumstellar envelopes and also shock waves arising from the
pulsations of the central star compared with SiO masers. This result
may also be related to the differences in the maser location and
pumping mechanism between H2O and SiO masers. The full width at zero
power of SiO masers in Mira variables shows similar values to those of
OH/IR stars, while those of H2 O masers in OH/IR stars show larger
values than those of Mira variables. These differences may originate
from the different mass-loss rates and the different location of the
two masers. The mean velocity shift of SiO and H2O masers with
respect to the stellar velocity was investigated as a function of
optical phase. The velocity shift of the H2O masers shows that the
redshifted emission dominates during the phases from 0.3-0.6, while
the blueshifted emission appears at phase 0.6 and coexists with the
redshifted emission during other phases. These features show an
associated pattern with the CO ΔV=3 radial velocity curve, which
exhibits a typical pulsation motion. On the other hand, the velocity
shift of the SiO v=2 maser shows slightly similar features to the
H2O maser, while that of SiO v=1 does not show these similar
features. Finally, the distributions of all 401 observed sources are
investigated in the IRAS two-color diagram in relation to the late
evolutionary processes of asymptotic giant branch stars.
Description:
Based on the observational results of previous papers (Paper I, Kim et
al., 2010ApJS..188..209K 2010ApJS..188..209K; Paper II, Cho & Kim, 2012, cat.
J/AJ/144/129; Paper III, Kim et al., 2013, cat. J/AJ/145/22), we have
established homogeneous observational data for SiO and H2O maser
properties including peak and integrated intensity ratios, photon
luminosities, Full Widths at Zero Power (FWZPs) and their ratios, and
the velocity shifts with respect to stellar velocities for all 401
observed evolved stars.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 79 361 Photon luminosity of detected sources
table3.dat 64 361 Full Width at Zero Power (FWZP) and velocity
shift of detected sources
refs.dat 67 30 References
--------------------------------------------------------------------------------
See also:
II/264 : ASAS Variable Stars in Southern hemisphere (Pojmanski+, 2002-2005)
V/18 : Catalogue of Late-type Stars with Maser Emission (Engels, 1979)
J/AJ/145/22 : Simultaneous SiO and H2O maser observations (Kim+, 2013)
J/AJ/144/129 : Properties of 83 known stellar SiO maser sources (Cho+, 2012)
J/PASJ/64/4 : SiO maser survey of nearby red variables (Deguchi+, 2012)
J/ApJ/669/446 : Observations of SiO masers (Nakashima+, 2007)
J/PASJ/56/765 : SiO maser survey of IRAS sources (Deguchi+, 2004)
J/PASJ/55/203 : SiO maser survey toward inner Galactic disk (Nakashima+, 2003)
J/PASJ/55/229 : SiO maser survey of cold IRAS sources (Nakashima+, 2003)
J/A+AS/101/153 : Galactic H2O masers (Palagi+ 1993)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq [1/166] Source number in previous paper
5- 7 A3 --- Pap Previous paper (I, II, or III) (G1)
9- 23 A15 --- Name Source name
25- 31 F7.2 10-20W/m2 FSiO1 ? Integrated flux for SiO(ν=1) maser line
33- 38 F6.2 10-20W/m2 FSiO2 ? Integrated flux for SiO(ν=2) maser line
40- 45 F6.2 10-20W/m2 FH2O ? Integrated flux for H2O maser line
47- 51 F5.2 [ph/s] LSiO1 ? Log of photon luminosity for SiO(ν=1) line
53- 57 F5.2 [ph/s] LSiO2 ? Log of photon luminosity for SiO(ν=2) line
59- 63 F5.2 [ph/s] LH2O ? Log photon luminosity for H2O maser line
65- 68 F4.2 --- Phase [0/1]? Phase of the optical light curve (1)
70- 76 F7.2 pc Dist ? Distance to source found in the literature
78- 79 I2 --- r_Dist ? Reference flag for Dist; in refs.dat file
--------------------------------------------------------------------------------
Note (1): At the epoch of observation. Calculated from the optical data
provided by the American Association of Variable Star Observers (AAVSO) and
the All Sky Automated Survey of Pojmanski (2002, cat. II/264).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq [1/166] Source number in previous paper
5- 7 A3 --- Pap Previous paper (I, II, or III) (G1)
9- 23 A15 --- Name Source name
25- 29 F5.2 km/s WSiO1 ? SiO ν=1 maser line FWZP (1)
31- 35 F5.2 km/s WSiO2 ? SiO ν=2 maser line FWZP (1)
37- 41 F5.2 km/s WH2O ? H2O maser maser line FWZP (1)
44- 47 F4.2 --- H2O/SiO ? Ratio of H2O to SiO ν=1 maser lines
50- 53 F4.1 km/s VSiO1 ? SiO ν=1 maser line mean velocity (2)
55- 58 F4.1 km/s VSiO2 ? SiO ν=2 maser line mean velocity (2)
60- 64 F5.1 km/s VH2O ? H2O maser line mean velocity (2)
--------------------------------------------------------------------------------
Note (1): FWZP = Full Width at Zero Power, i.e., velocity range between the
limits of the blue and red line edges where the maser emission decreased to
the noise level.
Note (2): Velocity with respect to stellar velocity. The mean velocity
has the same meaning as the velocity centroid of McIntosh
(2006AJ....132.1046M 2006AJ....132.1046M).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: refs.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Ref Reference number
4- 22 A19 --- BibCode Bibliographic code
24- 46 A23 --- Aut Author's name
48- 67 A20 --- Cat VizieR catalog
--------------------------------------------------------------------------------
Global notes:
Note (G1): Previous papers are:
I = Kim et al. (2010ApJS..188..209K 2010ApJS..188..209K);
II = Cho & Kim (2012, J/AJ/144/129);
III = Kim et al. (2013, J/AJ/145/22).
History:
From electronic version of the journal
References:
Kim et al., Paper I, 2010ApJS..188..209K 2010ApJS..188..209K
Cho & Kim, Paper II, 2012AJ....144..129C 2012AJ....144..129C, Cat. J/AJ/144/129
Kim et al., Paper III, 2013AJ....145...22K 2013AJ....145...22K, Cat. J/AJ/145/22
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 03-Sep-2014