Spectral energy distribution for GJ406
We present results of modelling the bulk of the spectral energy distribution (0.45–5 μm) for GJ406 (M6V). Synthetic spectra were calculated using the NextGen model atmospheres of Hauschildt et al. [6] and the incorporate line lists for H2O, TiO, CrH, FeH, CO, MgH molecules as well as the VALD line l...
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| Zitieren: | Spectral energy distribution for GJ406 / Yu. Lyubchik, Ya.V. Pavlenko, H.R.A. Jones, J. Tennyson, D. Pinfield // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 279-282. — Бібліогр.: 14 назв. — англ. |
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irk-123456789-796592015-04-04T03:01:47Z Spectral energy distribution for GJ406 Lyubchik, Yu. Pavlenko, Ya.V. Jones, H.R.A. Tennyson, J. Pinfield, D. MS3: Physics of Stars and Galaxies We present results of modelling the bulk of the spectral energy distribution (0.45–5 μm) for GJ406 (M6V). Synthetic spectra were calculated using the NextGen model atmospheres of Hauschildt et al. [6] and the incorporate line lists for H2O, TiO, CrH, FeH, CO, MgH molecules as well as the VALD line list of atomic lines. The computed water partition function is in a good agreement with the one obtained by Vidler & Tennyson [14]. A comparison of synthetic and observed spectra gives Teff = 2900 ± 100 K for this late M-dwarf. The William Herschel Telescope and United Kingdom Infrared Telescope are operated for the Particle Physics and Astronomy Research Council (PPARC). ISO is an ESA project with the participation of ISAS and NASA funded from member states. HST is a NASA project funded in part by ESA. This work was partially supported by a PPARC visitors grants from PPARC and the Royal Society. YP’s studies are partially supported by a Small Research Grant from American Astronomical Society. This research has made with the use of the SIMBAD database, operated at CDS, Strasbourg, France. 2005 Article Spectral energy distribution for GJ406 / Yu. Lyubchik, Ya.V. Pavlenko, H.R.A. Jones, J. Tennyson, D. Pinfield // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 279-282. — Бібліогр.: 14 назв. — англ. 0233-7665 http://dspace.nbuv.gov.ua/handle/123456789/79659 en Кинематика и физика небесных тел Головна астрономічна обсерваторія НАН України |
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MS3: Physics of Stars and Galaxies MS3: Physics of Stars and Galaxies Lyubchik, Yu. Pavlenko, Ya.V. Jones, H.R.A. Tennyson, J. Pinfield, D. Spectral energy distribution for GJ406 Кинематика и физика небесных тел |
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We present results of modelling the bulk of the spectral energy distribution (0.45–5 μm) for GJ406 (M6V). Synthetic spectra were calculated using the NextGen model atmospheres of Hauschildt et al. [6] and the incorporate line lists for H2O, TiO, CrH, FeH, CO, MgH molecules as well as the VALD line list of atomic lines. The computed water partition function is in a good agreement with the one obtained by Vidler & Tennyson [14]. A comparison of synthetic and observed spectra gives Teff = 2900 ± 100 K for this late M-dwarf. |
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Article |
| author |
Lyubchik, Yu. Pavlenko, Ya.V. Jones, H.R.A. Tennyson, J. Pinfield, D. |
| author_facet |
Lyubchik, Yu. Pavlenko, Ya.V. Jones, H.R.A. Tennyson, J. Pinfield, D. |
| author_sort |
Lyubchik, Yu. |
| title |
Spectral energy distribution for GJ406 |
| title_short |
Spectral energy distribution for GJ406 |
| title_full |
Spectral energy distribution for GJ406 |
| title_fullStr |
Spectral energy distribution for GJ406 |
| title_full_unstemmed |
Spectral energy distribution for GJ406 |
| title_sort |
spectral energy distribution for gj406 |
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Головна астрономічна обсерваторія НАН України |
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2005 |
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MS3: Physics of Stars and Galaxies |
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http://dspace.nbuv.gov.ua/handle/123456789/79659 |
| citation_txt |
Spectral energy distribution for GJ406 / Yu. Lyubchik, Ya.V. Pavlenko, H.R.A. Jones, J. Tennyson, D. Pinfield // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 279-282. — Бібліогр.: 14 назв. — англ. |
| series |
Кинематика и физика небесных тел |
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AT lyubchikyu spectralenergydistributionforgj406 AT pavlenkoyav spectralenergydistributionforgj406 AT joneshra spectralenergydistributionforgj406 AT tennysonj spectralenergydistributionforgj406 AT pinfieldd spectralenergydistributionforgj406 |
| first_indexed |
2025-07-06T03:40:59Z |
| last_indexed |
2025-07-06T03:40:59Z |
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1836867397293703168 |
| fulltext |
SPECTRAL ENERGY DISTRIBUTION FOR GJ406
Yu. Lyubchik1, Ya. V. Pavlenko1, H. R. A. Jones2, J. Tennyson3, D. Pinfield2
1Main Astronomical Observatory, NAS of Ukraine
27 Akademika Zabolotnoho Str., 03680 Kyiv, Ukraine
e-mails: lyu@mao.kiev.ua, yp@mao.kiev.ua
2Centre for Astrophysics Research, Science and Technology Research Centre, University of Hertfordshire
College Lane, Hatfield, Hertfordshire AL10 9AB, UK
e-mail: hraj@star.herts.ac.uk
3Department of Physics and Astronomy, University College London
Gower Street, London WC1E 6BT, UK
We present results of modelling the bulk of the spectral energy distribution (0.45–5μm) for GJ406
(M6V). Synthetic spectra were calculated using the NextGen model atmospheres of Hauschildt
et al. [6] and the incorporate line lists for H2O, TiO, CrH, FeH, CO, MgH molecules as well as
the VALD line list of atomic lines. The computed water partition function is in a good agreement
with the one obtained by Vidler & Tennyson [14]. A comparison of synthetic and observed spectra
gives Teff = 2900 ± 100 K for this late M-dwarf.
INTRODUCTION
The spectral energy distributions for several model atmospheres with effective temperatures around 3000 K
were computed and compared with the observed fluxes of GJ406. Using this procedure we pursue several
goals. First, we test the quality of the existing molecular and atomic line lists. Second, we investigate
the possibility for the use of the NextGen model atmospheres to compute the spectral energy distribution of
late type dwarfs.
OBSERVATIONS
Table 1 lists the information on observational spectra used for our investigations. The observed fluxes are shown
in Fig. 1.
Table 1. Observational data
Waverange, μm Instrument (configuration) Telescope Date
0.35 – 0.56 ISIS (blue arm) WHT 2001 Jan 29
0.55 – 0.80 ISIS (red arm) WHT 2001 Jan 29
0.79 – 1.20 NICMOS (G096) HST 1998 June 19
1.05 – 1.95 NICMOS (G141) HST 1998 June 19
1.3 – 2.59 NICMOS (G206) HST 1998 June 19
2.48 – 2.60 SWS (06 1A) ISO 1996 June 26
2.60 – 2.75 SWS (06 1A) ISO 1996 June 26
2.74 – 2.90 SWS (06 1A) ISO 1996 June 26
2.88 – 3.02 SWS (06 1B) ISO 1996 June 26
3.03 – 3.23 CGS4 (150 l/mm) UKIRT 1993 April 20
3.21 – 3.40 CGS4 (150 l/mm) UKIRT 1993 April 20
3.36 – 3.75 CGS4 (75 l/mm) UKIRT 1992 May 7
3.76 – 4.15 CGS4 (75 l/mm) UKIRT 1992 May 7
4.51 – 4.90 CGS4 (75 l/mm) UKIRT 1992 October 26
c© Yu. Lyubchik, Ya. V. Pavlenko, H. R. A. Jones, J. Tennyson, D. Pinfield, 2004
279
0
1
2
3
4
5
6
7
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Fl
ux
F
ν
Wavelength (micron)
n
m
l
k
j
i
h
g
f
e
d
c
b
a
a) ISIS (blue arm) on WHT at 2001 Jan 29
b) ISIS (red arm) on WHT at 2001 Jan 29
c) NICMOS (G096) on HST at 1998 June 19
d) NICMOS (G141) on HST at 1998 June 19
e) NICMOS (G206) on HST at 1998 June 19
f) SWS (06 1A) on ISO at 1996 June 26
g) ibid
h) ibid
i) SWS (06 1B) on ISO at 1996 June 26
j) CGS4 (150 l/mm) on UKIRT at 1993 20 April
k) ibid
l) CGS4 (75 l/mm) at 1992 May 7
m) ibid
n) CGS4 (75 l/mm) 1992 October 26
Figure 1. Observational data used for our analysis. The wavelength coverage of various instruments is shown
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
No
rma
lise
d F
lux
F ν + C
ons
t
Wavelength (micron)
H2O
CO
CrH
FeH
TiO
VALD
Figure 2. Contribution of different molecules to the formation of spectrum of GJ406
PROCEDURE
Synthetic spectra were computed for the NextGen model atmospheres [6] with the following parameters: effective
temperatures Teff = 2600–3600 K, log g = 5.0, solar metallicity [1] and microturbulent velocity vt = 2 km/s.
Calculations of synthetic spectra were carried out by using the program WITA6 [10] assuming LTE, hydrostatic
equilibrium for an one-dimensional model atmosphere and absence of sources and sinks of energy. The equations
of the ionization-dissociation equilibrium were solved for media consisting of atoms, ions, and molecules. We
took into account about 100 components [10]. The constants for equations of the chemical balance were taken
from [13].
Molecular line data were taken from various sources. The 1H16
2 O lines were calculated using the AMES
database [9]. The partition functions of H2O were also calculated from these data (see [11]). The 12C16O and
13C16O line lists were calculated by Goorvitch [4]. The CO partition functions were taken from [5], a TiO line
list – from [12]. CN lines were taken from CDROM 18 by Kurucz [8], CrH and FeH lines – from [2] and [3],
respectively. An atomic line list was taken from VALD [7].
The relative importance of the different opacities contributing to our synthetic spectra is shown in Fig. 2.
280
0
1
2
3
4
5
6
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
N
or
m
al
is
ed
F
lu
x
F
λ
Wavelength(micron)
GJ406
2600/5.0
0
1
2
3
4
5
6
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
N
or
m
al
is
ed
F
lu
x
F
λ
Wavelength(micron)
GJ406
2800/5.0
0
1
2
3
4
5
6
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
N
or
m
al
is
ed
F
lu
x
F
λ
Wavelength(micron)
GJ406
3000/5.0
Figure 3. Fits of the GJ406 spectra to the theoretical spectra computed for the NextGen model atmospheres
281
RESULTS
Dependence of fits on input parameters
We computed synthetic spectra using various input parameters such as effective temperatures, gravities, metal-
licities, microturbulent velocities. And we found that temperature has a relatively greater effect on the spectra
than metallicity and gravity. A temperature change of 200 K is roughly equivalent to a change in metallicity of
0.5 dex or a gravity of log g = 1.
Fits to GJ406 spectra
Fits of our synthetic spectra, which were computed for the NextGen model atmospheres with different Teff ,
to the GJ406 spectrum are shown in Fig. 3. Previous studies have considered GJ406 as a typical M6 dwarf,
therefore, log g = 5.0 was adopted. From our comparison of computed and observed spectra we assumed
Teff = 2900 ± 100 K.
Acknowledgements. The William Herschel Telescope and United Kingdom Infrared Telescope are operated for
the Particle Physics and Astronomy Research Council (PPARC). ISO is an ESA project with the participation
of ISAS and NASA funded from member states. HST is a NASA project funded in part by ESA. This work
was partially supported by a PPARC visitors grants from PPARC and the Royal Society. YP’s studies are
partially supported by a Small Research Grant from American Astronomical Society. This research has made
with the use of the SIMBAD database, operated at CDS, Strasbourg, France.
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