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1

Discovery and Observations of the Unusually Luminous Type-Defying II-P/II-L Supernova ASASSN-13co

Holoien T. W.-S., Prieto J. L., Pejcha O., Stanek Z., Kochanek C. S., Shappee B. J., Grupe D., Morrell N., Thorstensen J. R., Basu U., Beacom J. F., Bersier D., Brimacombe J., Davis A. B., Pojmański G., Skowron D. M.

Acta Astronomica

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2016

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Vol. 66, No. 2

219--238

EN

We present photometric and spectroscopic observations of ASASSN-13co, an unusually luminous Type II supernova and the first core-collapse supernova discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN). First detection of the supernova was on UT 2013 August 29 and the data presented span roughly 3.5 months after discovery. We use the recently developed model by Pejcha and Prieto to model the multi-band light curves of ASASSN-13co and derive the bolometric luminosity curve. We compare ASASSN-13co to other Type II supernovae to show that it was unusually luminous for a Type II supernova and that it exhibited an atypical light curve shape that does not cleanly match that of either a standard Type II-L or Type II-P supernova.

2

The All Sky Automated Survey. The Catalog of Bright Variable Stars in the I-band, South of Declination +28°

Sitek M., Pojmański G.

Acta Astronomica

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2014

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Vol. 64, No. 2

115--123

EN

This paper presents the results of our extensive search for the bright variable stars in approximately 30 000 square degrees of the south sky in the I-band data collected by 9°×9° camera of the All Sky Automated Survey between 2002 and 2009. Lists of over 27 000 variable stars brighter than 9 mag at maximum light, with amplitudes ranging from 0.02 mag to 7 mag and variability time-scales from hours to years, as well as corresponding light curves are provided. Automated classification algorithm based on stellar properties (period, Fourier coefficients, 2MASS J, H, K, colors, ASAS V-band data) was used to roughly classify objects. Despite low spatial resolution of the ASAS data (&assymp;15'') we cross-identified all objects with other available data sources. Coordinates of the most probable 2MASS counterparts are provided. 27 705 stars brighter than I=9$ mag were found to be variable, of which 7842 objects were detected to be variable for the first time. Brief statistics and discussion of the presented data is provided. All the photometric data is available over the Internet at http://www.astrouw.edu.pl/~gp/asas/AsasBrightI.html

3

Large Magellanic Cloud Cepheids in the ASAS Data

Karczmarek P., Dziembowski W. A., Lenz P., Pietrukowicz P., Pojmański G.

Acta Astronomica

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2011

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Vol. 61, No. 4

303--318

EN

A catalog of Cepheids in the Large Magellanic Cloud (LMC) from the ASAS project is presented. It contains data on 65 fundamental mode pulsators with periods longer than about 8 days. The period-luminosity (PL) relation in the V-band does not significantly differ from the relation determined from the OGLE-III data extended toward longer periods but shows much larger scatter. For objects with periods longer than 40 d there is an evidence for a shallower PL relation. The rates of long-term period variations significant at 3σ level are found only for seven objects. The rates for 25 objects determined with the 1σ significance are confronted with the values derived from stellar evolution models. The models from various sources yield discrepant predictions. Over the whole data range, a good agreement with measurements is found for certain models but not from the same source.

4

The All Sky Automated Survey. The Catalog of Variable Stars in the Kepler Field of View

Pigulski A., Pojmański G., Pilecki B., Szczygieł D. M.

Acta Astronomica

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2009

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Vol. 59, No. 1

33--46

EN

We present the catalog of 947 variable stars located in the field of view of the Kepler satellite. The catalog is a result of the analysis of VI photometry obtained during the first 17-month observations in the ASAS3-North station. The variable stars we present are divided into eleven groups according to the presented variability; the groups are briefly discussed. The catalog is intended to be a source of information for target selection process and follow-up programs.

5

Galactic Fundamental Mode RRLyrae Stars. Period-Amplitude Diagram, Metallicities and Distribution

Szczygieł D. M., Pojmański G., Pilecki B.

Acta Astronomica

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2009

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Vol. 59, No. 2

137--167

EN

We have analyzed 1455 fundamental mode RR Lyr stars of the Galactic field, using the All Sky Automated Survey (ASAS) data. The sample covers 75% of the sky and contains objects in the close neighborhood of the Sun, within 4 kpc distance. Unlike in the previous analysis of the close field RRab stars, we see a clear manifestation of the Oosterhoff groups on the period-amplitude diagram. The relation for Oosterhoff I type variables becomes strongly flattened at large V amplitudes, which was not observed for globular cluster RR Lyr. We calculate photometric metallicities using two available methods: one of Jurcsik and Kovács (1996) and the other of Sandage (2004). We find significant discrepancies between results from both methods. Comparison with spectroscopic metallicities undoubtedly favors the method of Jurcsik and Kovács (1996). In addition, we notice that RRab stars of Oosterhoff II type might follow a different metallicity-period-phase relation than Oosterhoff I type variables. The spatial distribution of Galactic field RRab stars does not show any metallicity gradients with distance from the Galactic center in either of the Oosterhoff groups. However, both the older, metal poor Oosterhoff II variables and the metal rich Oosterhoff I RRab stars become more concentrated to the Galactic plane with increasing metal content.

6

Coronal Activity from the ASAS Eclipsing Binaries

Szczygieł D. M., Socrates A., Paczyński B., Pojmański G., Pilecki B.

Acta Astronomica

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2008

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Vol. 58, No. 4

405--418

EN

We combine the catalog of eclipsing binaries from the All Sky Automated Survey (ASAS) with the ROSAT All Sky Survey (RASS). The combination results in 836 eclipsing binaries that display coronal activity and is the largest sample of active binary stars assembled to date. By using the (V-I) colors of the ASAS eclipsing binary catalog, we are able to determine the distances and thus bolometric luminosities for the majority of eclipsing binaries that display significant stellar activity. A typical value for the ratio of soft X-ray to bolometric luminosity is L_X/L_bol≈ a few ×10^-4, similar to the ratio of soft X-ray to bolometric flux F_X/F in the most active regions of the Sun. Unlike rapidly rotating isolated late-type dwarfs - stars with significant outer convection zones - a tight correlation between Rossby number and activity of eclipsing binaries is absent. We find evidence for the saturation effect and marginal evidence for the so-called ``super-saturation'' phenomena. Our work shows that wide-field stellar variability searches can produce a high yield of binary stars with strong coronal activity.

7

The All Sky Automated Survey. Catalog of Variable Stars. V. Declinations 0° - +28° of the Northern Hemisphere

Pojmański G., Pilecki B., Szczygieł D.

Acta Astronomica

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2005

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Vol. 55, No. 3

275--301

EN

This paper contains the fifth part of the Catalog of Variable Stars created from the V-band photometric data collected by 9°×9° camera of the All Sky Automated Survey. Preliminary list of variable stars found in the fields located between declination 0° and +28° of the northern hemisphere is presented. 11 509 stars brighter than V=15 mag were found to be variable (2 482 eclipsing, 1 397 regularly pulsating, 318 Miras and 7 310 other stars). Automated algorithm taking into account light curve properties (period, Fourier coefficients) and other available data (2MASS colors, IRAS fluxes) was applied to roughly classify the objects. This paper concludes our preliminary efforts to detect variable stars brighter than V≈14 mag over the sky south of declination +28°. A short summary of the current ASAS Catalog of Variable Stars is presented and links to the on-line data are provided. All the photometric data are available over the INTERNET at http://www.astrouw.edu.pl/~gp/asas/asas.html or http://archive.princeton.edu/~asas

8

The All Sky Automated Survey. Catalog of Variable Stars. IV. 18h-24h Quarter of the Southern Hemisphere

Pojmański G., Maciejewski G.

Acta Astronomica

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2005

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Vol. 55, No. 1

97--122

EN

In this paper we present the fourth part of the photometric data from the 9ox9o ASAS camera monitoring the whole southern hemisphere in V-band. Preliminary list (based on observations obtained since January 2001) of variable stars located between RA 18h and 24h is released. 10311 stars brighter than V=15 mag were found to be variable (1641 eclipsing, 1116 regularly pulsating, 938 Mira-type and 6616 other stars). Light curves have been classified using the automated algorithm taking into account periods, amplitudes, Fourier coefficients of the light curves, 2MASS colors and IRAS infrared fluxes. Basic photometric properties are presented in the tables and some examples of thumbnail light curves are printed for reference. All photometric data are available over the INTERNET at http://www.astrouw.edu.pl/~gp/asas/asas.html or http://archive.princeton.edu/~asas

9

The All Sky Automated Survey. Catalog of Variable Stars. III. 12h - 18h Quarter of the Southern Hemisphere

Pojmański G., Maciejewski G.

Acta Astronomica

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2004

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Vol. 54, No. 2

153--179

EN

This paper describes the third part of the photometric data from the 9°×9° ASAS camera monitoring the whole southern hemisphere in V-band. Preliminary list of variable stars based on observations obtained since January 2001 is presented. Over 3 200 000 stars brighter than V=15 mag on 18 000 frames were analyzed and 10 453 were found to be variable (1718 eclipsing, 731 regularly pulsating, 849 Mira and 7155 other stars). Light curves have been classified using the improved automated algorithm, which now takes into account 2MASS colors and IRAS infrared fluxes. Basic photometric properties are presented in the tables and some examples of thumbnail light curves are printed for reference. All photometric data are available over the INTERNET at: http://www.astrouw.edu.pl/~gp/asas/asas.html or http://archive.princeton.edu/~asas.

10

The All Sky Automated Survey. The Catalog of Variable Stars. II. 6h-12h Quarter of the Southern Hemisphere

Pojmański G.

Acta Astronomica

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2003

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Vol. 56, No. 4

341--369

EN

This paper describes the second part of the photometric data from the 9°×9° ASAS camera monitoring the whole southern hemisphere in the V-band. Preliminary list of variable stars based on observations obtained since January 2001 is presented. Over 2 800 000 stars brighter than V=15 mag on 18 000 frames were analyzed and 11357 were found to be variable (2685 eclipsing, 907 regularly pulsating, 521 Mira and 7244 other, mostly SR, IRR and LPV stars). Periodic light curves have been classified using the automated algorithm, which now takes into account IRAS infrared fluxes. Basic photometric properties are presented in the tables and some examples of thumbnail light curves are printed for reference. All photometric data are available over the INTERNET at http://www.astrouw.edu.pl/~gp/asas/asas.html or http://archive.princeton.edu/~asas.

11

The All Sky Automated Survey. The Catalog of Variable Stars. II. 0h-6h Quarter of the Southern Hemisphere

Pojmański G.

Acta Astronomica

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2002

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Vol. 52, No. 4

397--427

EN

This paper describes the first part of the photometric data from the 9°×9° ASAS camera monitoring the whole southern hemisphere in the V-band. Data acquisition and reduction pipeline are described and preliminary list of variable stars presented. Over 1 300 000 stars brighter than V=15 mag on 10 000 frames were analyzed and 3126 were found to be variable (1055 eclipsing, 770 regularly pulsating, 132 Mira and 1169 other, mostly SR, IR and LPV stars). Periodic light curves have been classified using the fully automated algorithm, which is described in detail. Basic photometric properties are presented in the tables and exemplary light curves are printed for reference. All photometric data are available over the Internet at http://www.astrouw.edu.pl/~gp/asas/asas.html or http://archive.princeton.edu/~asas.

12

The All Sky Automated Survey. Catalog of about 3800 Variable Stars

Pojmański G.

Acta Astronomica

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2000

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Vol. 50, No. 2

177--190

EN

Results of the first two years of observations using the All Sky Automated Survey prototype camera are presented. More than 140 000 stars in 50 Selected Fields covering 300 square degrees were monitored each clear night in the I-band resulting in the ASAS Photometric I-band Catalog containing over 5×107 individual measurements. Nightly monitoring of over 100 standard stars confirms that most of our data remains within σI=0.03 mag of the standard I system. Search for the stars varying on the time scales longer than a day revealed about 3800 variable stars (mostly irregular, pulsating and binaries) brighter than 13 mag. Only 630 of them are known or suspected variables included in the GCVS (Kholopov 1985). Among the stars brighter than I≈7.5 (which are saturated on our frames) we have found about 50 variables (12 are in the GCVS, 6 others in the Hipparcos catalog. Because of the large volume of data we present here only selected tables and light curves, but the complete ASAS Catalog of Variable Stars (currently divided into Periodic and Miscellaneous sections) and all photometric data are available on the Internet http://www.astrouw.edu.pl/~gp/asas/asas.html or http://archive.princeton.edu/~asas/

13

Spectroscopic Observations of IX Vel

Kubiak M., Pojmański G., Krzemiński W.

Acta Astronomica

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1999

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Vol. 49, No. 1

73--84

EN

We present phase-resolved spectroscopic observations of IX Vel (the brightest known novalike cataclysmic binary of UX UMa type) in the wavelength range 810-920 nm. We try to explain the relatively complicated shape of the observed emission lines in terms of the three component model of the emission from the system: disk, secondary star, "hot spot". The model reproduces the observations sufficiently well and confirms the presence of a narrow emission components in CaII triplet changing radial velocity in anti-phase relative to the orbital motion.

14

The All Sky Automated Survey. The Catalog of the Periodic Variable Stars in the Selected Fields

Pojmański G.

Acta Astronomica

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1998

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Vol. 48, No. 1

35--58

EN

Results of the first two months of observations using the All Sky Automated Survey prototype camera are presented. More than 45 000 stars in 24 Selected Fields covering 140 square degrees were monitored a few times per night resulting in the I-band catalog containing 107 individual measurements. Period search revealed 126 variable stars brighter than 13 mag with periods less than 20d. Only 30 of them are known variable stars included in the General Catalogue of Variable Stars. The other 90 objects are newly detected variable stars - mainly eclipsing binaries (75%) and pulsating stars (17%). We estimate that completeness of the current catalogs of variable stars is smaller than 50% already for the stars brighter than 9 mag. The Catalog is accessible over the WWW: http://www.astrouw.edu.pl/~gp/asas/asas.html

15

Orbital Solutions for Three RS CVn Systems: WY Cnc, SV Cam and XY UMa

Pojmański G.

Acta Astronomica

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1998

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Vol. 48, No. 4

711--727

EN

Near IR spectroscopic observations of WY Cnc, SV Cam and XY UMa binary systems of RS CVn type are presented. Systemic velocity and radial velocity semi-amplitudes of primary components in each system are derived using cross-correlation between cleaned spectra and G2 noiseless templates. Secondary semi amplitudes are determined from the primary subtracted spectra using the cross-correlation function maps and direct cross-correlation. Masses of the stars are derived and system properties briefly discussed. Primary components in all three systems seem to be more massive than was earlier deduced from their spectral classification. Regarding stellar masses, SV Cam should be classified as F5V+K0V pair. Observations of XY UMa fully confirm results obtained previously using a method for detecting faint secondaries in the low signal-to-noise spectra.