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VII Bulgarian-Serbian Astronomical Conference
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ASTROINFORMATICS
Astroinformatics for the Flare Stars in Stellar Clusters and
Associations
Katya Tsvetkova
Institute of Mathematics and Informatics,
Institute of Astronomy,
Bulgarian Academy of Sciences
Chepelare, Bulgaria, June 1-4, 2010
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Flare Star Definition
Flare activity:
- a very quick increase of the brightness and a decline from maximum to minimum for
some minutes up to some hours;
- a common characteristic in the early evolution of all red dwarf stars.
Belonging:
- to the population of young stellar clusters and associations.
Flare-like activity: some Wolf-Rayet stars, stars of B and A spectral types, RS Cvn
system, some members of Algol and W UMa systems, FK Com stars and even evolved
systems, containing white dwarfs.
All observed characteristics - energy, amplitudes, time-scales, frequencies, shows
differences which could be due to the different origin. That is why collecting flare star
data we have restricted the observed phenomena - so called flares, classical flares,
flashes, microflaring, to the UV Ceti type variability as is classified in the General
Catalogue of Variable Stars (GCVS, Kholopov et al. 1985).
Chepelare, Bulgaria, June 1-4, 2010
Flare Star Light Curves
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LS6=ABC145
14 Jan 1985
Min (pg)=16.75
Max(pg)=15.60
Delta m=1.35
Chepelare, Bulgaria, June 1-4, 2010
International .Cooperative Programme for Flare Star Searches in
. Stellar Clusters and Associations
Observatories: Tonantzintla, Byurakan, Asiago, Abastumani, Konkoly, Rozhen, etc.
Period: 1960 – 1995.
Wide-field telescopes: Schmidt or Maksutov type.
Method: photographic multi-exposure plate observations by the method of stellar
chains.
Chepelare, Bulgaria, June 1-4, 2010
Results
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from the. Flare Star Monitoring Optical Observations
in Stellar Clusters and Associations
Stellar cluster
or association
Number of
flare stars
Number of
registered flares
Observing time
(hours)
Orion M42/M43
The Pleiades
Taurus Dark Clouds
Cygnus NGC 7000
Praesepe
NGC 2264
Cygnus IC 1318
Coma Open Cluster
Alpha Persei Cluster
Scorpius-Ophiuchus
Others
564
547
102
83
59
42
17
14
7
14
70
827
1635
122
120
146
43
18
21
7
15
70
1591
3250
870
1168
680
105
300
338
128
321
800
Total1
1519
3024
9551
Chepelare, Bulgaria, June 1-4, 2010
. Stars in Stellar Clusters and Associations
Flare
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600
564
547
Total Number of Flare Stars: 1519
400
300
200
102
83
100
70
59
42
17
14
7
14
Chepelare, Bulgaria, June 1-4, 2010
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Number of Flare Stars
500
. Stars in Stellar Clusters and Associations
Flare
.
1800
1635
1600
Total Number of Flare-ups: 3024
Number of Flare-ups
1400
1200
1000
827
800
600
400
200
122
120
146
43
18
21
7
15
Monoceros
CygnusII
Coma
Perseus
ScoOphi
70
0
Orion
Pleiades
Taurus
CygnusI
Praesepe
Chepelare, Bulgaria, June 1-4, 2010
Others
. Stars in Stellar Clusters and Associations
Flare
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Total Observing Time: 9551 hours
8%
1%
3%
Orion
Pleiades
Taurus
CygnusI
Praesepe
Monoceros
CygnusII
Coma
Perseus
ScoOphi
Others
17%
4%
3%
1%
7%
35%
12%
9%
Chepelare, Bulgaria, June 1-4, 2010
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Catalogues of Flare Stars
1. Machine-readable version of the Tonantzintla Pleiades Flare
Stars (Haro+ 1982), Boletin Inst. Tonantzintla 3, No. 1, 3, VizieR
Catalogue - II/131 since 1987.
2. Catalogues of the Cygnus flare stars (Tsvetkov and Tsvetkova,
1990), Proceedings of the 137th Symposium of the IAU Flare Stars
in Star Clusters Associations and the Solar Vicinity, eds. L. V.
Mirzoyan, B. R. Pettersen and M. K. Tsvetkov, Kluwer Academic
Publishers, p. 105.
3. Catalogue of flare stars in the Praesepe cluster (K.P.Tsvetkova,
M.K.Tsvetkov and I.Jankovics, 1991).
Chepelare, Bulgaria, June 1-4, 2010
Flare Stars Database (FSDB)
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Tsvetkova et al. 1995, Tsvetkova et al. 1996
Database not only for UV Ceti type stars, but also for their
registered flare-events, which are missing in the other existing
astronomical catalogues and data sets like GCVS, the Set of
Identifications, Measurements and Bibliography for Astronomical
Data (SIMBAD), and the Database on UV Ceti Type Flare Stars and
Related Objects (for 230 objects) of
Gershberg et al. (1993).
Chepelare, Bulgaria, June 1-4, 2010
Structure and Content of the FSDB
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MAIN DATA FILE
   
Flare-event identifier
Equatorial coordinates (R. A., DEC) of flare star for equinox J2000.0
Equatorial coordinates (R. A., DEC) of flare star for equinox J1950.0
Galactic coordinates in the l(II), b(II) system
Julian date of the flare-event
First registered flare-event
Telescope used
Stellar magnitude at minimum in U or Pg/ BPOSS bands
Stellar magnitudes at maximum in U- and Pg bands
Amplitudes in U and Pg bands
Criterion - m > 5
V magnitude, B-V and U-B indices at minimum
Spectral class
Aggregate membership
Pointers to tables SIMBAD and NOTES
   
File CROSS-IDENTIFICATION
File IDENTIFICATION CHARTS
File REFERENCES
File SIMBAD
File NOTES
Chepelare, Bulgaria, June 1-4, 2010
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Flare Stars Identifier
DF
CNC
750218
V 426
TAU
711112
1
V 426
TAU
721206
2
Chepelare, Bulgaria, June 1-4, 2010
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FSDB
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Identifier
RA Dec
(1950)
RA Dec
(2000)
Date
V1581CYG750706 1953.9+4425 1952.3 +4417 19750706001
V1513CYG710730 2005.1+5427 2003.9 +5418 19710730002
V1513CYG710731 2005.1+5427 2003.9 +5418 19710731002
V 426TAU690918
V 426TAU711112
V 426TAU721206
V 594TAU730226
V 485TAU681019
033042+2226
033042+2226
033042+2226
033042+2308
033048+2250
19690918001
19711112002
19721206003
19730226001
19681019001
DF
DF
DF
DF
DF
DF
DF
083524 +1815
083524 +1815
083524 +1815
083524 +1815
083524 +1815
083524 +1815
083524 +1815
19750218007
19750313007
19750402007
19760228007
19760325007
19760330007
19800319007
CNC750218
CNC750313
CNC750402
CNC760228
CNC760325
CNC760330
CNC800319
Chepelare, Bulgaria, June 1-4, 2010
. Flare Stars Database: Problems
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A most serious obstacle for the FSDB is the lack in the literature for
some stars of some necessary parameters of the flare-event: beginning of
flare-events, duration, flare star identification charts, in the GCVS the
information on stellar magnitude at minimum and maximum is not
sufficient for assigning the flare event parameters. Very often, the lack of
flare star identification charts is a reason for some missidentifications
and errors here (Tsvetkova and Tsvetkov, 1989).
Chepelare, Bulgaria, June 1-4, 2010
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Automated Flare Stars Search:
Results
When the plates are compared with a blink-comparator a selection effect due to the used 10-minute
duration of the single exposure, which is a low time resolution, appears. Thus it may preclude detection
of energetic, but low amplitude flare-events on bright stars. The flare star surveys with used flare star
monitoring photographic method of multi-exposure images each of 10-minute duration usually
discover the most chromospherically active stars. The less active stars could be missed. If the star is
very faint it will be impossible to observe small flares.
•An automated flare stars search method was applied for some
southern stellar aggregates with different age (Aniol et al. 1990,
Winterberg et al. 1995).
•This procedure removes partially the selection effect and increases
the number of discovered flares by 50 % compared to visual
inspection by a Zeiss-comparator.
•The number of slow flare events, flares on bright stars and on Intype variables was mainly increased.
Chepelare, Bulgaria, June 1-4, 2010
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Digital Plate Archives
According to the main observing programmes:
Aims: to assemble and explore massive data sets in order to reveal a new knowledge
existing in the data, but still not recognized in any individual data set.
Preparation of digital plate archives - as a part of the long-time programme for search,
preservation and re-usage of the world wide-field photographic astronomical plate
collections.
The last step before the systematic astronomical research:
The organization of the plate scans in an image database and the development of a
software system for object plate identifications and for searching in an image database
with many data storage variants as current tasks.
Chepelare, Bulgaria, June 1-4, 2010
. Digital Plate Archives: Examples
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•The Pleiades Plate Database - about 3100 plates obtained in the period 1885 – 1998
were found in the observatories in Asiago (Italy), Sonneberg (Germany), Harvard
(USA), Kyiv (Ukraine), Moscow (Russia), Rozhen (Bulgaria), Konkoly (Hungary),
Byurakan (Armenia), Potsdam (Germany), Edinburgh (UK), Bamberg (Germany). It
gives the opportunity to obtain almost continuous photometric data set for the red dwarf
stars in the cluster.
The precise coordinates of the known Pleiades flare stars were determined as a
necessary step to the further work of automated search for long-term brightness
variations.
The archive of the digitised plates in the Pleiades stellar cluster contains already about
1500 plates. The plate images are included into the developed Pleiades Plate Data Base
(PPDB, Borisova et al. 2003; Tsvetkov et al. 2005).
Chepelare, Bulgaria, June 1-4, 2010
Digital Plate Archives: Examples
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•Konkoly Supernova. Digital Plate Archive (Tsvetkova et al. 2008, Baltic Astronomy) observing programmes carried out with the 60/ 90/180 cm Schmidt telescope, started at
the end of 1963, with which Konkoly Observatory for about more than a 30-year period
took part in the international campaign initiated by F. Zwicky.
•Konkoly Flare Star Digital Archive – of representative plates obtained with the
Schmidt telescopes of Konkoly observatory during the observation campaign for search
and investigations of the flare stars in stellar clusters and associations in 1970-1990.
Besides the primary aim to serve for investigations of the flare stars another result is
the realization of an interlinking the electronic Information Bulletin on Variable Stars
(IBVS) with the Wide-Field Plate Database (WFPDB). The plates are scanned with
resolution 1200 dpi for plate visualization and to preserve the observer marks. The
image is saved as TIFF file format with size 51.12MB and as JPEG file (compressed to
2000x2000 pixels) with size 1.65MB. After the cleaning the observer marks the plate is
scanned with high resolution (2400 dpi) and saved as FITS file with size 409 MB.
•Carte du Ciel Plate Digital Archives – Uccle (Tsvetkova et al. 2007), Potsdam
(Tsvetkova et al. 2009, Astronomische Nachrichten).
Chepelare, Bulgaria, June 1-4, 2010
Rozhen Flare Stars Digital Plate Archives
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Now having at disposal an observing material from the monitoring flare star
observations in the Rozhen Observatory, done with the 50/70/172 cm Schmidt
telescope in the period 1979 – 1994, we are going to apply an automated flare stars
search method on the basis of scanned flare stars monitoring plates of the Rozhen
Observatory.
Chepelare, Bulgaria, June 1-4, 2010
Rozhen Flare Stars Observations:Telescope
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50/70/172 cm Schmidt
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Chepelare, Bulgaria, June 1-4, 2010
Rozhen Flare Stars Observations:Telescope
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50/70/172 cm Schmidt
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Chepelare, Bulgaria, June 1-4, 2010
Rozhen Flare Stars Observations:Telescope
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50/70/172 cm Schmidt
Main Characteristics
WFPDB Tel.Orig. Aperture Focal
Scale Tel. Field
Years of
Plate
Instr. Ident. Name
(m)
Length (m) "/mm Type Size (deg) Operation Number
ROZ050
Schmidt
0.50/0.70 1.72
120
Sch
4.5
Chepelare, Bulgaria, June 1-4, 2010
1979-1994
7348
Plate
Library in Rozhen Observatory
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Chepelare, Bulgaria, June 1-4, 2010
. Rozhen Flare Stars Observations:
Number of Plates
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Stellar clusters and associations: the Pleiades, Gamma Cygni
region, M42/43 in Orion, Praesepe, Alpha Per, Tauri Dark Clouds,
the open cluster NGC 2264, the emission nebula NGC 7000.
Number of Plates: totally 1564 plates.
Chepelare, Bulgaria, June 1-4, 2010
. Rozhen Flare Stars Observations:
Number of Plates
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Chepelare, Bulgaria, June 1-4, 2010
Rozhen Flare Stars Observations:Telescope
WFPDB ROZ050 Catalogue
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Chepelare, Bulgaria, June 1-4, 2010
Rozhen Flare Stars Observations:
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Emulsions and Plate Size
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Used emulsions: ORWO, Kodak
Plate Size: 13x13 cm; 16x16 cm
Chepelare, Bulgaria, June 1-4, 2010
Rozhen. Flare Stars Digital Plate Archive: Scanners
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Sofia Sky Archive Data Center:
PDS1010plus microdensitometer with possibility for high precision;
Flatbed Scanner: EPSON EXPRESSION 1640XL
Flatbed Scanner: EPSON PERFECTION V700 PHOTO
Rozhen Observatory:
Flatbed Scanner: EPSON EXPRESSION 10000XL
Chepelare, Bulgaria, June 1-4, 2010
Sofia
. Sky Archive Data Center: FB Scanner
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EPSON EXPRESSION
1640XL
Scanning platform:
310x437 mm;
Resolution: 1600x3200dpi,
Duration: 5min 16x16 cm
plate;
Plate Storage: FITS with
volume 120 MB.
Chepelare, Bulgaria, June 1-4, 2010
. Rozhen Observatory: FB Scanner
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EPSON EXPRESSION
10000XL
Scanning platform:310x437
mm
Resolution: 1600x3200dpi
Duration: 5min 16x16 cm
Plate Storage: FITS
2m RCC plates 30x30 cm
Previews:Adobe Photoshop
600dpi, 24bit colour
TIFF; JPEG
Scans: Scanfits
1600dpi, 16bit grayscale
FITS (612MB)
Chepelare, Bulgaria, June 1-4, 2010
Rozhen. Flare Stars Digital Plate Archive: Scanning
. Main parameters of the available flatbed scanners
Scanner
1640XL
10000XL
Dmax
3.6
3.8
Color depth
Grayscale depth
Resolution (dpi)
42/42
14/14
1600
42/42
16/16
2400x4800
The used software for scanning is the standard one for making preview images - Adobe
Photoshop, and the programme Scanfits for the real scans in FITS format.
Chepelare, Bulgaria, June 1-4, 2010
Rozhen. Flare Stars Digital Plate Archive: Scanning
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Preview images: aim: easier web accessibility and to store the information from the
observer’s marks on the plate a system for quick plate visualization
Parameters: 1200 dpi in TIFF format and compressed 1000x1000 pxl JPEG format;
color depth:
8-bit 24 bit Color
Real scans:
Scanning Parameters: 2400 dpi, FITS format, density range (0 – 255) and Gamma =
1.00; color depth - 16-bit Grayscale.
Chepelare, Bulgaria, June 1-4, 2010
Rozhen Flare
Stars Digital Plate Archive: Scanned plates
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ROZ050 000291
Gamma Cyg region
Chepelare, Bulgaria, June 1-4, 2010
Rozhen Flare. Stars Digital Plate Archive : Scanned plates
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ROZ050 000383
M42/43 region
Chepelare, Bulgaria, June 1-4, 2010
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Acknowledgements
This work is supported by the Bulgarian National Science
Fund (grant BG NSF DO-02-275).
Chepelare, Bulgaria, June 1-4, 2010