Low-resolution spectroscopy of the chromospherically active stars 61 Cyg AB with small telescopes
We carried out high-speed low-resolution spectroscopy of two stars, 61 Cyg A and B with small telescopes. They are known as chromospherically active stars of the K5V (A) and K7V (B) spectral types. These two stars are supposed to have high-powered chromospheres. Spectroscopic monitoring of both star...
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Головна астрономічна обсерваторія НАН України
2014
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| Цитувати: | Low-resolution spectroscopy of the chromospherically active stars 61 Cyg AB with small telescopes / S.M. Pokhvala, B.E. Zhilyaev, V.M. Reshetnyk, V.I. Shavlovskij // Advances in Astronomy and Space Physics. — 2014. — Т. 4., вип. 1-2. — С. 25-27. — Бібліогр.: 5 назв. — англ. |
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irk-123456789-1198062017-06-10T03:03:17Z Low-resolution spectroscopy of the chromospherically active stars 61 Cyg AB with small telescopes Pokhvala, S.M. Zhilyaev, B.E. Reshetnyk, V.M. Shavlovskij, V.I. We carried out high-speed low-resolution spectroscopy of two stars, 61 Cyg A and B with small telescopes. They are known as chromospherically active stars of the K5V (A) and K7V (B) spectral types. These two stars are supposed to have high-powered chromospheres. Spectroscopic monitoring of both stars showed variations of intensity in the Balmer lines and the Mg b triplets at time intervals ranging from seconds to several minutes. From the spectrum data one can find that relative variations in the Hα, Hβ lines and the Mg b triplets are about 1% and the relative power of chromospheric activity about 2 · 10⁻⁴. 2014 Article Low-resolution spectroscopy of the chromospherically active stars 61 Cyg AB with small telescopes / S.M. Pokhvala, B.E. Zhilyaev, V.M. Reshetnyk, V.I. Shavlovskij // Advances in Astronomy and Space Physics. — 2014. — Т. 4., вип. 1-2. — С. 25-27. — Бібліогр.: 5 назв. — англ. 2227-1481 DOI: 10.17721/2227-1481.4.25-27 http://dspace.nbuv.gov.ua/handle/123456789/119806 en Advances in Astronomy and Space Physics Головна астрономічна обсерваторія НАН України |
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We carried out high-speed low-resolution spectroscopy of two stars, 61 Cyg A and B with small telescopes. They are known as chromospherically active stars of the K5V (A) and K7V (B) spectral types. These two stars are supposed to have high-powered chromospheres. Spectroscopic monitoring of both stars showed variations of intensity in the Balmer lines and the Mg b triplets at time intervals ranging from seconds to several minutes. From the spectrum data one can find that relative variations in the Hα, Hβ lines and the Mg b triplets are about 1% and the relative power of chromospheric activity about 2 · 10⁻⁴. |
| format |
Article |
| author |
Pokhvala, S.M. Zhilyaev, B.E. Reshetnyk, V.M. Shavlovskij, V.I. |
| spellingShingle |
Pokhvala, S.M. Zhilyaev, B.E. Reshetnyk, V.M. Shavlovskij, V.I. Low-resolution spectroscopy of the chromospherically active stars 61 Cyg AB with small telescopes Advances in Astronomy and Space Physics |
| author_facet |
Pokhvala, S.M. Zhilyaev, B.E. Reshetnyk, V.M. Shavlovskij, V.I. |
| author_sort |
Pokhvala, S.M. |
| title |
Low-resolution spectroscopy of the chromospherically active stars 61 Cyg AB with small telescopes |
| title_short |
Low-resolution spectroscopy of the chromospherically active stars 61 Cyg AB with small telescopes |
| title_full |
Low-resolution spectroscopy of the chromospherically active stars 61 Cyg AB with small telescopes |
| title_fullStr |
Low-resolution spectroscopy of the chromospherically active stars 61 Cyg AB with small telescopes |
| title_full_unstemmed |
Low-resolution spectroscopy of the chromospherically active stars 61 Cyg AB with small telescopes |
| title_sort |
low-resolution spectroscopy of the chromospherically active stars 61 cyg ab with small telescopes |
| publisher |
Головна астрономічна обсерваторія НАН України |
| publishDate |
2014 |
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http://dspace.nbuv.gov.ua/handle/123456789/119806 |
| citation_txt |
Low-resolution spectroscopy of the chromospherically active stars 61 Cyg AB with small telescopes / S.M. Pokhvala, B.E. Zhilyaev, V.M. Reshetnyk, V.I. Shavlovskij // Advances in Astronomy and Space Physics. — 2014. — Т. 4., вип. 1-2. — С. 25-27. — Бібліогр.: 5 назв. — англ. |
| series |
Advances in Astronomy and Space Physics |
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AT pokhvalasm lowresolutionspectroscopyofthechromosphericallyactivestars61cygabwithsmalltelescopes AT zhilyaevbe lowresolutionspectroscopyofthechromosphericallyactivestars61cygabwithsmalltelescopes AT reshetnykvm lowresolutionspectroscopyofthechromosphericallyactivestars61cygabwithsmalltelescopes AT shavlovskijvi lowresolutionspectroscopyofthechromosphericallyactivestars61cygabwithsmalltelescopes |
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2025-07-08T16:38:29Z |
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2025-07-08T16:38:29Z |
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1837097507760373760 |
| fulltext |
Low-resolution spectroscopy of the chromospherically
active stars 61CygAB with small telescopes
S.M.Pokhvala1∗, B. E. Zhilyaev1, V.M.Reshetnyk2, V. I. Shavlovskij1
Advances in Astronomy and Space Physics, 4, 25-27 (2014)
© S.M.Pokhvala, B. E. Zhilyaev, V.M.Reshetnyk, V. I. Shavlovskij, 2014
1Main Astronomical Observatory of the NAS of Ukraine, Akademika Zabolotnoho str., 27, 03680 Kyiv, Ukraine
2Taras Shevchenko National University of Kyiv, Glushkova ave., 4, 03127 Kyiv, Ukraine
We carried out high-speed low-resolution spectroscopy of two stars, 61CygA and B with small telescopes. They
are known as chromospherically active stars of the K5V (A) and K7V (B) spectral types. These two stars are
supposed to have high-powered chromospheres. Spectroscopic monitoring of both stars showed variations of inten-
sity in the Balmer lines and the Mgb triplets at time intervals ranging from seconds to several minutes. From the
spectrum data one can �nd that relative variations in the Hα, Hβ lines and the Mgb triplets are about 1% and the
relative power of chromospheric activity about 2 · 10−4.
Key words: instrumentation: detectors, methods: observational, techniques: image, processing techniques: spec-
trometric, stars: imaging
introduction
Main chromospheric activity indicator is the pres-
ence of a distinct emission component in the nuclei
of the H and K Caii and hydrogen lines. These emis-
sions, for example, in spectra of Arcturus and some
other stars vary periodically, by analogy with the so-
lar cycle. It is assumed that these variations are as-
sociated with micro�ares, the main source of coronal
heating in chromospherically active stars.
61CygAB are BYDra type variables. Long-
term X-ray monitoring of 61Cyg binary with XMM-
Newton was used to investigate possible coronal ac-
tivity cycles [2]. The X-ray light curves were com-
pared with the long-term monitoring of chromo-
spheric activity, as measured by the Mt. Wilson
Caii H+K S-index. Besides variability on short time
scales, typical for the RYDra type variables, long-
term variations of the X-ray activity were found
clearly present. For 61CygA distinct chromospheric
activity cycle was found resembling the solar be-
haviour. The coronal activity of 61CygB also fol-
lows the chromospheric variability. 61CygA was the
�rst star where a persistent coronal activity cycle has
been observed [2].
The hydrogen Balmer lines are formed at the mid-
dle chromosphere. In active stars they often show
�lled-in absorption features. They can be used also
as a diagnostic tool for the presence of plages and
prominences on the stellar surface.
The purpose of this work was the detection of
rapid variations of spectral lines in sub-second range.
Spectra and variations in the spectra at di�erent
time scales allow us to con�rm the presence of rapid
variations in the sub-second range for both stellar
components of 61Cyg.
observations
We present low-dispersion (R ∼ 100) optical
(3900�8000Å) spectra of 61CygAB binary stars ob-
tained with the AZT-2 (D = 70 cm, F = 10.5m) and
the Sky Watcher 1201 EQ5 (D = 12 cm, F = 1m)
telescopes. They are equipped with the di�rac-
tion grating �The Star Analyzer SA-200� for low-
dispersion spectroscopy. We used the Atik CCD
Camera 314L and the commercial DSLR Camera
Canon 350D.
On August 18, 2013, we obtained 305 low-
resolution grating spectrograms of 61CygAB.
The observations were acquired with the AZT-2
Cassegrain telescope in Kiev equipped with a grism
spectrograph [5], and the Atik CCD Camera 314L.
The exposure time was 0.1 s and the sampling inter-
val of 0.9 s. The spectrograms cover a wavelength
range from about 3700Å to 9000Å, and have a res-
olution of R ∼ 100. The signal-to-noise ratio is typ-
ically about 100.
We obtained also 100 low-resolution grating spec-
trograms of 61CygA with the Sky Watcher 1201
EQ5 on March 13, 2014, equipped with the com-
mercial DSLR Camera Canon 350D. The exposure
time was 2.0 s at ISO800, the read-out time was 3 s,
and the sampling interval was 5.0 s. The spectro-
grams cover a wavelength range from about 4100Å
to 6800Å, and have the spectral resolution 51Å per
∗nightspirit10@gmail.com
25
Advances in Astronomy and Space Physics S.M.Pokhvala, B. E. Zhilyaev, V.M.Reshetnyk, V. I. Shavlovskij
pixel in the vicinity of the Hβ line. The signal-
to-noise ratio is typically about 10 for a star of
V = 5.21. A sample spectrum is shown in Fig. 1.
Spectroscopic monitoring of 61CygAB sar in the
quiescent state showed variations in the Balmer
lines Hα (6563Å), Hβ (4861Å) and the Mgb triplets
(5163�5186Å) in the sub-second range.
Fig. 1: A sample of raw spectrum of 61CygA with the
Sky Watcher 1201 EQ5, equipped with the commercial
DSLR Camera Canon 350D.
results and conclusions
Spectroscopic monitoring of the �spotted� stars
61CygA, B showed variations in the Balmer lines
and, perhaps, the Caii H, K lines, as well as in
the Mgb triplets in the sub-second range (Figs. 2�4).
The relative variations usually de�ned as an r.m.s.
deviation divided by the mean.
Fig. 2 depicts a plot of relative power variations
in the spectra depending on the wavelength. Note
�emission� features in the spectra of 61CygA at
wavelengths of the Balmer lines Hβ , Hδ and, pos-
sibly, the Caii H, K lines. Using the spectrum data
one can �nd that the total variations in the intensi-
ties of the Hβ line is about 1% and about 0.5% in
Hδ and the relative power of chromospheric activity
is about of 2 · 10−4. The relative power of chromo-
spheric activity was estimated as a ratio of variations
in the active lines to the luminosity of a star on the
whole.
Fig. 3 demonstrates detectable activity in the
spectrum of 61CygB in the Balmer lines Hα and
Hβ on the short timescale down to 0.9 s.
Variations in the Balmer line Hβ and the Mgb
triplets in Fig. 4 reveal di�erent activity on 61CygA
acquired another day than depicts in Fig. 2.
Of prime importance, that the spectrum data
obtained with di�erent resolving time demonstrate
transient activity in the Balmer lines and, possibly,
the Caii H, K lines. The di�erent time resolution
follows from the initial 0.9 s resolution data rebinned
over 9, 45, 90 s intervals. The presence of peaks in
variations of spectra indicates the transient nature
of chromospheres' activity in both stars 61Cyg.
As it was mentioned by [1], variability of the chro-
mospherically active stars could be explained by as-
suming that the heating of its corona results from a
large number of small �ares. It is well-known that
the solar corona is heated by the two most favoured
agents involving magnetic �elds, namely magneto-
hydrodynamical waves and transients, such as �ares,
micro- and nano�ares (see [3] and references therein).
Fig. 2: The relative variations are shown in the spectrum
of 61CygA from a sample of 305 time-resolved spectra.
Peaks of activity are clearly visible in the short-wave
part of the spectrum. The variation curves are calcu-
lated from samples with a time resolution from 0.9 to 90
seconds.
Fig. 3: Variations shown in the spectrum of 61CygB
demonstrate detectable activity in the Hα and Hβ
Balmer lines on the timescale of 0.9 s.
26
Advances in Astronomy and Space Physics S.M.Pokhvala, B. E. Zhilyaev, V.M.Reshetnyk, V. I. Shavlovskij
Fig. 4: Variations in the Balmer line Hβ and the Mgb
triplets of 61CygA acquired with the DSLR Camera
Canon 350D.
Photometric observations of three chromospher-
ically active stars showed high-frequency variations
in brightness in the UBV bands at sub second range
[4]. Intensity variations are found peaked at fre-
quency around about 0.5 Hz, spanning the range
up to 1.5Hz for BD+15 3364, II Peg, and up to
about 35Hz for SAO 52355. High-frequency changes,
which were found in these stars suggests the exis-
tence of intense micro�aring. Hence it follows, that
time-resolved spectra could demonstrate activity on
time scales compatible with radiative lifetime of �are
events.
It appears that the observed variability patterns
on 61CygAB can be related to an ensemble of mi-
cro�ares with a duration ranging from tenths to tens
of seconds.
references
[1] Alekseev I. Yu. & KozlovaO.V. 2003, A&A, 403, 205
[2] HempelmannA., Robrade J., Schmitt J.H.M.M. et al.
2006, A&A, 460, 261
[3] ParkerE.N. 1991, in `Mechanisms of Chromospheric and
Coronal Heating', Proc. of the International Conference,
Heidelberg, 5�8 June 1990, XV, eds.: UlmschneiderP.,
Priest E.R. & RosnerR., Springer-Verlag, Berlin, Heidel-
berg, New York, 615
[4] ZhilyaevB.E., AndreevM.V. & SergeevA.V. 2011,
[arXiv:1109.5207]
[5] ZhilyaevB.E., SergeevA.V., AndreevM.V. et al. 2013,
Kinematics and Physics of Celestial Bodies, 29, 3, 120
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