Open Access Published by De Gruyter Open Access

Volume 12 Issue 4

December 2003

Issue of Open Astronomy

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Contents
Journal Overview

Open Access February 8, 2017

Preface

J. Sūdžius, V. Straižys, A. G. Davis Philip

Page range: 431-431

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Open Access February 8, 2017

Stellar Photometry at the Crossroads of the Two Centuries

V. Straižys

Page range: 433-446

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Abstract

In the last century photometry was recognized as a powerful method for investigation of physical parameters of stars and of interstellar matter. Photometric investigations now cover the spectral range from the far ultraviolet to the far infrared. The article describes the most important landmarks in development of photometric classification of stars and the number of photometric survey projects accomplished by ground-based and space telescopes and including millions of point sources. The success of the future LSSD and Gaia projects will depend on the use of optimum photometric passbands.

Open Access February 8, 2017

Overview of Gaia Multi-Color Photometry

Erik Høg

Page range: 447-450

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Abstract

Gaia will obtain multi-color photometry for astrometric and astrophysical purposes. A photometry in five broad bands and with high angular resolution will be obtained after every astrometric observation of a star, especially for the sake of correcting slight astrometric chromaticity errors of the optical system. A separate smaller telescope will obtain photometry in eleven passbands of medium width designed to serve the astrophysical analysis of the mission results. The medium-band photometry (MBP) has less angular resolution, but much longer effective integration time than the broad-band photometry (BBP).

Open Access February 8, 2017

The Depth of the Heavens – Belief and Knowledge During 2500 Years

Erik Høg

Page range: 451-453

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Abstract

For Dante Alighieri (1265-1321) the spiritual cosmos contained the Heavens, Earth and Hell, and it was compatible with the physical cosmos known from Aristotle (384-322 B.C.). Dante’s many references in his Divine Comedy to physical and astronomical subjects show that he wanted to treat these issues absolutely correctly. Tycho Brahe proves three hundred years later by his observations of the Stella Nova in 1572 and of comets that the spheres of heavens did not really exist. It has ever since become more and more difficult to reconcile the ancient ideas of a unified cosmos with the increasing knowledge about the physical universe. Ptolemaios derived a radius of 20 000 Earth radii for the sphere of fixed stars. This radius of the visible cosmos at that time happens to be nearly equal to the true distance of the Sun, or 14 micro-light-years. Today the radius of the visible universe is a million billion (10 15 ) times larger than Tycho Brahe believed. The lecture gave an overview of astronomical distances and their dramatic change during two and a half millennia, the following text is an extract hereof.

Open Access February 8, 2017

Photometry of Variable Stars, and System Transformability Over Long Time Intervals

C. Sterken

Page range: 454-462

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Abstract

The fundamental problem of long-term photometric monitoring of variable stars and of multi-wavelength photometric campaigns is the problem of bringing the data to a common standard. Such homogenization can be achieved only when the measurements are made in photometric systems that are truly transformable. This fundamental problem is of a technical nature, and photometric observers, sometimes, are not aware of the problems. This frequently leads to over-interpretation of the data.

Open Access February 8, 2017

Near Continuous Photometry with the Whole Earth Telescope (WET)

J. E. Solheim

Page range: 463-470

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Abstract

The Whole Earth Telescope (WET) saw first light in 1988. It was invented by scientists from the Astronomy Department, University of Texas at Austin. The idea was to generate a world-wide network of cooperating astronomical observatories to obtain uninterrupted time-series measurements of some variable stars. The technological goal was to resolve the multi-periodic oscillations in these objects into their individual components; the scientific goal was to construct accurate theoretical models of the target objects, constrained by their observed behavior, from which fundamental astrophysical parameters could be derived. This approach has been extremely successful, and has placed stellar seismology at the forefront of stellar astrophysics. The network is run as a single astronomical instrument with many operators, and the collaboration includes scientists from all continents on our planet, taking part in the observations, data reduction, analysis and theoretical interpretation. The expertise of Lithuanian astronomers in photometry, and their access to the observing station Mt. Maidanak in Uzbekistan, has been important for the success of the network.

Open Access February 8, 2017

Setting Up of the Strömvil System Standards and Standard Regions

A. G. Davis Philip, R. P. Boyle, V. Straižys, A. Kazlauskas

Page range: 471-476

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Abstract

CCD photometry of standard areas of the seven-color Strömvil photometric system in some open and globular clusters is described. The primary standards are being measured with a two-channel photoelectric photometer on the 1.5 meter telescope on Mt. Lemmon. CCD photometry of standard areas is in progress with the Vatican Advanced Technology Telescope on Mt. Graham and with the CASLEO 2.1 m telescope in Argentina. Two additional Strömvil projects are described.

Open Access February 8, 2017

Flatfielding Errors in Strömvil CCD Photometry

R. P. Boyle, R. Janusz, A. G. Davis Philip, A. Kazlauskas, V. Laugalys

Page range: 476-483

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Abstract

The importance of determining the error of the flat field in CCD photometry is detailed and our methods of doing this are described. We now have reached a precision of 1-1.5 % in our photometry. Color-magnitude diagrams of the open cluster M67 (ours and Laugalys et al. 2003) are compared.

Open Access February 8, 2017

The Reduction of CCD Images for Stellar Photometry on the Vatt

R. Janusz, R. P. Boyle, A. G. Davis Philip

Page range: 484-490

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Abstract

We briefly describe a method of organizing all the star field exposures taken in a complete CCD observational run. By a “CommandLog” (to be published in J. Astron. Data) one can organize all the observations and process them within IRAF in an orderly, automated manner to arrive at stellar photometry calibrated into a standard photometric system (in our case, Strömvil). During the course of this processing we determine the error of the flat and try to correct it.

Open Access February 8, 2017

Calibration of the Strömvil Photometric System

A. Kazlauskas, V. Straižys, R. P. Boyle, A. G. Davis Philip, V. Laugalys, K. Černis, J. Sperauskas

Page range: 491-496

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Abstract

A calibration of color indices of the Strömvil photometric system in terms of physical parameters of stars is presented. The calibration is based on photoelectric photometry of about 1000 stars with known effective temperatures, distances, gravities and metallicities. The observations were accomplished in 2000-2003 with the 1.5 meter telescope of the Steward Observatory. The distances were taken from the Hipparcos catalog, and T e , log g, [Fe/H]) were collected from several literature sources and averaged.

Open Access February 8, 2017

Large-Scale Errors In CCD Photometry of M67

V. Laugalys, R. P. Boyle, A. Kazlauskas, F. J. Vrba, A. G. Davis Philip, V. Straižys

Page range: 497-502

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Abstract

The accuracy of new CCD photometry in the Vilnius system of the M67 cluster is analyzed. The observational material is obtained during six observing runs in 1994-2001 with the 1 meter telescope of the USNO Flagstaff Station. The main task was to establish CCD standards of high accuracy and to eliminate large-scale errors from our CCD photometry. We compare our results with the published CCD photometric data in other photometric systems. The comparison reveals considerable systematic errors in some datasets.

Open Access February 8, 2017

The Development of Stellar Photometry in Russia and the USSR in the 20Th Century (Some Pages of History)

A. V. Mironov

Page range: 503-507

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Abstract

A short historical review of the development of astrophotometry in Russia and the Soviet Union is given. The input of V. Cerasky, G. Tikhov, V. B. Nikonov, Moscow University astronomers and Vilnius astronomers is described.

Open Access February 8, 2017

Luminosity and Intrinsic Color Calibration of Main-Sequence Stars With 2Mass Photometry: All Sky Local Extinction

Jens Knude, Claus Fabricius

Page range: 508-513

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Abstract

We present a new color index vs. absolute magnitude calibration of 2MASS JHK photometry. For the A0 to ~G5 and M segments of the main sequence information on the amount of interstellar extinction and its location in space may be obtained.

Open Access February 8, 2017

Interstellar Extinction from Large Surveys

O. Yu. Malkov

Page range: 514-519

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Abstract

Under some assumptions, information on interstellar extinction may be obtained from modern large photometric survey data. Virtual Observatory facilities allow users to make a fast and correct cross-identification of objects from various surveys. This process yields multicolor photometry data for registered objects and makes it possible to estimate color excesses and, with a few exceptions for some areas with high total-to-selective extinction ratio, calculate interstellar extinction. A 3D extinction map then can be constructed for almost the whole sky. The method is applied to an area with the low Galactic latitude, and the results are discussed in the present paper.

Open Access February 8, 2017

Variations of the Ratio of Total-To-selective Extinction in the Galaxy

J. Sūdžius, S. Raudeliūnas

Page range: 520-525

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Abstract

The results of the study of variations of total-to-selective extinction R V near the Galactic plane (-12° ≤ b ≤+12°) are presented. It is shown that variations of R V range from 1.9 to 3.4 and it is not possible to determine its typical value for the Galaxy. The conclusion that variations of the parameter R V closely correlates with the distribution of interstellar extinction is confirmed.

Open Access February 8, 2017

Star Formation Histories with Gaia: The Galaxy and Beyond

A. Kučinskas, L. Lindegren, T. Tanabé, Savanorių Vansevičius

Page range: 526-531

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Abstract

ESA’s Gaia mission will provide accurate astrometric, photometric and spectroscopic data for millions of stars in the Galaxy and beyond. We discuss the prospects of using this vast amount of astrophysical information for understanding star formation histories in the Galaxy and its immediate neighbors within the Local Group.

Open Access February 8, 2017

Selecting a Photometric System for Gaia: C, N, O and Alpha-Process Elements

G. Tautvaišienė, B. Edvardsson, S. Bartašiūtė

Page range: 532-538

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Abstract

The sensitivity of stellar spectra to C, N, O and α-process element abundances is discussed with the aim of taking this effect into account when selecting a photometric system for the Gaia orbiting observatory. On the basis of a spectrometric, photometric and theoretical study of spectra of evolved first-ascent giants and clump stars in the open cluster NGC 7789 it is demonstrated that evolutionary alterations of carbon and nitrogen abundances can cause noticeable spectral changes and, if not taken into account, may yield misleading photometric [Fe/H] determinations. Carbon features in stellar atmospheres show a particularly complex behavior being dependent on mixing processes in stars, on the stellar surface gravity and on the abundance of oxygen which can also be altered by different reasons. NH bands could serve for the evaluation of mixing processes in stars and the interpretation of carbon dominated spectral regions. Abundances of α-process elements can be evaluated photometrically by using the direct indicators - Ca II H and K lines and Mg I b triplet.

Open Access February 8, 2017

Stellar Populations of the Galactic Disk: Metallicity Distribution and Kinematics

S. Bartašiūtė, Z. Aslan, R. P. Boyle, N. V. Kharchenko, L. P. Ossipkov, J. Sperauskas

Page range: 539-546

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Abstract

Metallicities and distances have been determined from Vilnius photometry for an in situ sample of nearly 650 stars in eight proper-motion fields at high Galactic latitudes. For half of these stars, radial velocities have been measured with the CORAVEL spectrometer, which allowed us to derive spatial velocities and Galactic orbits. In this contribution we present a status report on our results for the stellar content of the Galactic disk, with emphasis given to specific aspects of distinguishing the thick-disk stars from the old thin-disk population.

Open Access February 8, 2017

Classification of Metal-Deficient Dwarfs in the Vilnius Photometric System

R. Lazauskaitė, A. Bartkevičius, S. Bartašiūtė

Page range: 547-554

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Abstract

Methods used for the quantitative classification of metal-deficient stars in the Vilnius photometric system are reviewed. We present a new calibration of absolute magnitudes for dwarfs and subdwarfs, based on Hipparcos parallaxes. The new classification scheme is applied to a sample of Population II visual binaries.

Open Access February 8, 2017

High-Precision UBVRI Photometry with a New 50 Cm Telescope at Stará Lesná

T. Pribulla, D. Chochol

Page range: 555-560

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Abstract

The paper presents the experience, observations and results obtained with the new 50 cm photometric telescope at the Stará Lesná Observatory equipped with an SBIG ST10MXE CCD camera. The telescope time is devoted to observations of variable stars of various types. Prospects for further improvement of the instrument, observational and reduction techniques are discussed.

Open Access February 8, 2017

Principles and Applications of the Synchronous Network of Remote Telescopes

B. E. Zhilyaev, Ya. O. Romanyuk, O. A. Svyatogorov, I. A. Verlyuk

Page range: 561-567

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Abstract

A new approach for the search of microvariability and high-speed phenomena in variable stars is presented. It gives a new technology of observation and analysis of the data. Statistical photometry stands on the three pillars: the digital filtering technique, the photon counting statistics based on the Mandel equation, and the integral transforms of the light curves. This technique permits to investigate low-amplitude and rapid variability of stars.

Open Access February 8, 2017

Fast CCD Photometry in the Taiwan-America Occultation Survey

W. P. Chen, Z. W. Zhang, S. K. King, C. Alcock, Y. I. Byun, K. H. Cook, R. Dave, J. Giammarco, T. Lee, M. Lehner, C. Liang, J. Lissauer, S. Marshall, I. de Pater, R. Porrata, J. Rice, A. Wang, S. Y. Wang, C. Y. Wen

Page range: 568-573

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Abstract

We describe the efforts of the Taiwan-America Occultation Survey (TAOS) project to develop a data acquisition and analysis scheme for fast CCD imaging photometry. The TAOS project aims to conduct a census of the Kuiper-belt objects (KBOs) by detecting chance stellar occultation events by these small bodies in the outer reach of the solar system. An array of telescopes, each with fast optics (f/2) of 0.5 m aperture and equipped with a 2K CCD camera (3 square degrees FOV), have been set up in central Taiwan to monitor a couple thousand stars simultaneously. By reading out the CCD chip sequentially a few rows of pixels at a time (pause-and-shift), it is possible to achieve stellar photometry with a sampling rate up to several hertz. Here we report how such a setup has been used to observe the SX Phoenicis type variable CY Aqr to illustrate the potential usefulness of the TAOS database in stellar variability studies.

Open Access February 8, 2017

The Whole Earth Telescope Arrives to Lithuania

E. G. Meištas

Page range: 574-577

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Abstract

A short description of participation of the Lithuanian astronomers in the Whole Earth Telescope program is given.

Open Access February 8, 2017

Molėtai Observatory as a Part of The Whole Earth Telescope

R. Janulis

Page range: 578-583

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Abstract

A short description is presented of the instrumentation used at the Molėtai Observatory (Lithuania) for the Whole Earth Telescope collaboration and an overview of the observation campaigns in which the Vilnius WET group took part.

Open Access February 8, 2017

On the Data Reduction of WET Observations

Erika Pakštienė

Page range: 584-588

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Abstract

It is demonstrated how the length of a continuous time-series of photometric data and their gaps affect the power spectrum of a Fourier Transform of the data. It is shown that second order effects of the atmospheric extinction - the dependence of the extinction coefficient on spectral type of a star and on the air mass - cannot be ignored. The ignoring of these effects results in aliases at frequencies lower than 200 μHz. A modification of the extinction correction procedure is proposed.

Open Access February 8, 2017

On a New Technique for Discovering Variable Stars

A. V. Mironov, A. I. Zakharov, F. N. Nikolaev

Page range: 589-594

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Abstract

A technique for discovering variable stars based on the calculation of the correlation coefficients is proposed. Applications of the technique are shown on the results of numerical experiments and on the Hipparcos photometric data.

Open Access February 8, 2017

Long-Term Photometric Behavior of 18 Carbon Stars in Cygnus

A. Alksnis

Page range: 595-603

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Abstract

The large variety of long-term (secondary) variations is demonstrated on the basis of a 30 year long photographic red magnitude time-series for 18 carbon stars in Cygnus based on the observations carried out with the Baldone Schmidt telescope.

Open Access February 8, 2017

Correction of UBV Photometry for Emission Lines

A. Skopal

Page range: 604-609

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Abstract

We investigate the effect on U,B,V magnitudes of the removal of emission lines from the spectra of some symbiotic stars and novae during their nebular phases. We approach this problem by the precise reconstruction of the composite UV/optical continuum and the line spectrum. The corrections ΔU, ΔB and ΔV are determined from the ratio of fluxes with and without emission lines. We demonstrate the effect for symbiotic nova V1016 Cyg during its nebular phase. We find that about 68%, 78% and 66% of the observed flux in the U, B and V filters is radiated in the emission lines. The effect should be taken into account before using the observed color indices of emission-line objects for diagnosis of their radiation in the continuum.

Open Access February 8, 2017

Long-Term Photometry of Very Slow Novae

D. Chochol, T. Pribulla, Š. Parimucha, M. Vaňko

Page range: 610-615

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Abstract

Long-term photographic, photoelectric and recent CCD photometry of the classical nova V723 Cas and symbiotic novae V1329 Cyg, PU Vul, V1016 Cyg and HM Sge were used to find their orbital periods. The arguments in favor of the presence of the third components in these systems are given. Physical processes, responsible for the brightness variations, are discussed.

Open Access February 8, 2017

Near-Infrared Colors of Carbon Stars in Cygnus

A. Alksnis, Z. Alksne

Page range: 616-617

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Abstract

The J-H, H-K diagram based on the 2MASS Sky Survey for 140 carbon stars in Cygnus, which have been photometrically monitored with the Baldone Schmidt telescope, is discussed.

Open Access February 8, 2017

Some Photometric Characteristics of Population II Orbital Visual Binary Stars

A. Bartkevičius, A. Gudas

Page range: 618-621

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Abstract

A M V ,B−V diagram for metal-deficient, kinematically selected thick disk and halo visual binary stars with known orbits is presented. The magnitude differences Δm between the components are analyzed.

Open Access February 8, 2017

On the Period of the Mira Variable LX Cygni

A. Barzdis, A. Alksnis

Page range: 622-623

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Abstract

The period changes of the SC-type Mira variable LX Cygni are analyzed.

Open Access February 8, 2017

Interstellar Extinction in the Gaia Photometric Systems

A. Bridžius, V. Vansevičius

Page range: 624-628

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Abstract

Three medium-band photometric systems proposed for the Gaia space mission are intercompared in determining color excesses for stars of spectral classes from O to M at V = 18 mag. A possibility of obtaining a three-dimensional map of the interstellar extinction is discussed.

Open Access February 8, 2017

Ultraviolet Passbands for a Space Multicolor Photometric System

A. R. Ambartsoumian, A. V. Mironov, A. I. Zakharov

Page range: 629-630

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Abstract

The results of search for the optimal location of ultraviolet passbands for an extra-atmospheric photometric system are given. The addition of passbands near the well-known extinction bump at 218 nm to the photometric system makes it possible to determine interstellar extinction with greater precision than with the photometric system without UV passbands.

Open Access February 8, 2017

Recent UBVR Photometry of Symbiotic Stars

A. Skopal, M. Vaňko, T. Pribulla, D. Chochol

Page range: 631-632

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Abstract

We present recent photometric observations of Z And, BF Cyg, and AX Per made in the standard Johnson UBVR system. The main characteristics of their light behavior can be summarized as follows: Z And: our observations cover the recent active phase, from its maximum in 2000 December to the latest measurements (2003 September). BF Cyg: the minimum of the recent wave in the star’s brightness was the deepest ever observed; in 2003 February a short-term flare developed in the light curve. AX Per: from 1995 October the light curve displays signatures of a quiescent phase of the star; in 2003 May a 0.5 mag flare was detected.

Open Access February 8, 2017

Modeling the Radial Color Profile of M31

D. Semionov, R. Stonkutė, V. Vansevičius

Page range: 633-636

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Abstract

We present a preliminary study of a fragment of the radial color profile of the spiral galaxy M 31 in terms of 2-D model accounting for internal extinction in the disk. The two stellar population disk model was assumed. The old dust-free disk population is represented by the double exponential law, and the young disk population, well mixed with the dust, resides in spiral arms of various scale-heights. We find a good agreement among the radial color B-R profiles produced by this simple model and the profile measured around the spiral arm S4 of M 31.

Open Access February 8, 2017

On the Accuracy of Gaia Photometry

G. Abromavičius, R. Drazdys, A. Skrebutėnas, V. Vansevičius

Page range: 637-638

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Abstract

The errors of Gaia photometry originating from tolerancies of the light filter mean wavelengths and half-widths are investigated.

Open Access February 8, 2017

Dual-Star Photometer at the Tallinn Observatory

P. Kalv, V. Harvig, T. Aas, I. Pustylnik

Page range: 639-641

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Abstract

We briefly describe the dual-star photometer designed by P. Kalv, a former director of Tallinn Observatory (1934-2002) for multicolor photometry of close binaries and intrinsic variable stars.

Open Access February 8, 2017

A New CCD Camera at the Molėtai Observatory

J. Zdanavičius, K. Zdanavičius

Page range: 642-646

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Abstract

The results of the first testing of a new CCD camera of the Molėtai Observatory are given. The linearity and the flat field corrections of good accuracy are determined by using shifted star field exposures.

Open Access February 8, 2017

Experience in CCD Photometry at the Tartu Observatory

T. Tuvikene, I. Kolka

Page range: 647-648

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Abstract

We give overview of the CCD instrumentation and data reduction techniques used at the Tartu Observatory. The first results from photometric observations of the peculiar variable V838 Mon are presented.

Open Access February 8, 2017

Overview of the History of Vilnius University Observatory

L. Klimka

Page range: 649-656

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Abstract

An overview of the early history of the Astronomical Observatory of Vilnius University from its foundation in 1753 to 1878 is presented.

About this journal

Past events:

The Hubble Tension: Current Research and New Perspectives
Modern Stellar Astronomy 2022
New Technology for Space Environment Detection Based on Beidou Constellation
New Progress in Astrodynamics Applications
Modern Stellar Astronomy 2021
The Global Space Exploration Conference (GLEX) 2021
Astromineralogy and cosmochemistry of the Kaba meteorite: A massage from the early Solar System

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Open Astronomy is a peer-reviewed, fully open access online journal, that publishes research, reviews and news spanning all aspects of astronomy and astrophysics.

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