Bayesian approach to estimating stellar properties and interstellar extinction law based on photometry

We describe Bayesian probabilistic approach to estimating the properties of stars and the interstellar extinction law based on photometric observations and using prior data about the parameters of the stars. The accuracy of the resulting estimates is analyzed in the case of SDSS and 2MASS surveys. We found that our estimates have no systematic deviations in the case of photometric accuracy typical of the surveys considered and errors of prior data of ΔT _eff = ±150 K and Δ_{log g} = ±0.5. Note that the error of the estimated interstellar extinction A ₀ is of about 0_. ^m 3, and the error of the R ₀ estimate depends on extinction and is close 0.2 for moderate A0 values. The fractional error of the estimated stellar angular diameters is close to 10%. A possible application of our approach is to determine the dependence of interstellar extinction on distance using stars closely located in the same sky area.     

Interstellar extinction toward the ultradeep Galactic field of the Chandra observatory from 2MASS data

We have measured the interstellar extinction in the region of ultradeep Galactic-field observations by the Chandra telescope (l ^II, b ^II) ≈ 0.1–1.42 using photometric data from the 2MASS infrared allsky survey. The angular resolution of our interstellar extinction map is 1′.8. We show that the interstellar extinction has a minimum, A _V ～ 3.4, near the center of the Chandra field of view and increases to A _V ～ 5.8–6 at the edge of the field of view. In addition, we show that the bulk of the extinction is gained in the Galactic disk and is approximately the same for all bulge stars. Our results will be subsequently used to process the Chandra data and to estimate the properties of the stellar population in this region.     

OB stars in the Tycho-2 and 2MASS catalogues

The Tycho-2 proper motions and five-band Tycho-2 and 2MASS photometry for approximately 2.5 million common stars have been used to select OB stars and to determine the extinction and photometric distance for each of them. We have selected 37 485 stars and calculated their reddenings based on their positions in the two-color V _T -H, J-Ks diagrams relative to the zero-age main sequence and the theoretical reddening line for B5 stars. Tests confirm that the selected stars belong to the spectral types O-B with a small admixture of later types. We calculate the extinction coefficient R and its variations with Galactic longitude based on the positions of the selected stars in the two-color B _T -V _T , V _T -Ks diagram. The interstellar extinction for each star is calculated as the product of the reddening found and the coefficient R. The extinction and its variations with Galactic longitude agree well with the extinction based on the model by Arenou et al. (1992). Calibration of the relation between the absolute magnitude and reduced proper motion V _T − + 5 + 5 log μ for Hipparcos stars has allowed us to calculate the absolute magnitudes and photometric distances for the selected stars. The distances found agree with those derived from the Hipparcos parallaxes within 500 pc. The distribution of the stars and the extinction variations with distance found show that the selected stars form an almost complete sample of stars with spectral types earlier than B5 within about 750 pc of the Sun. The sample includes many noticeably reddened stars in the first and second Galactic quadrants that are absent from the Hipparcos and Tycho Spectral Types Catalogues. This slightly changes the pattern of the distribution of OB stars compared to the classical pattern based on Hipparcos. Original Russian Text ? G.A. Goncharov, 2008, published in Pis’ma v Astronomicheskiĭ Zhurnal, 2008, Vol. 34, No. 1, pp. 10–20.     

Fundamental parameters and intrinsic colors of F,G, and K supergiants and classical cepheids

We used high-resolution echelle spectra with high signal-to-noise ratio to determine with a high degree of accuracy some atmospheric parameters (T _eff, log g and [Fe/H]) for 68 non-variable supergiants of types F, G, and K and 26 classical Cepheids in 302 pulsation phases. Very accurate effective temperatures, with errors of only 10–30 K, were determined by the line-depth ratio method. We found that the observed intrinsic color indices (B ? V)₀ can be related to these parameters: (B ? V)₀ = 57.984? 10.3587(log T _eff)² + 1.67572(log T _eff)³ ? 3.356 log g+ 0.321 V _t + 0.2615[Fe/H] + 0.8833log g(log T _eff). With this empirical relation, the intrinsic colors of individual supergiants and classical Cepheids of spectral types F0-K0 and of luminosity classes I and II can be estimated with an accuracy as high as 0.05 ^m , which is comparable to the accuracy of the most elaborate photometric procedures. In view of large distances to supergiants, the method we propose here allows a large-scale mapping of interstellar extinction with an accuracy of 0.1–0.2 ^m in a quite large region of the Galaxy.     

A Comprehensive Study of 94 Open Clusters Based on the Data from IPHAS,GAIA DR2, and Other Sky Surveys

We determine the color excesses, photometric distances, ages, astrometric parallaxes and proper motions for 94 open clusters in the northern part of the Milky Way. We estimate the color excesses and photometric distances based on the data from IPHAS photometric survey of the northern Galactic plane using individual total-to-selective extinction ratios R_r = A_r/E_r?i for each cluster computed via the color-difference method based on IPHAS r, i, and Hα-band, 2MASS J-, H-, and K_s-band, WISE W1-band, and Pan-STARRS i-, z-, and y-band data. The inferred R_r values vary significantly from cluster to cluster spanning the R_r = 3.1–5.2 interval with a mean and standard deviation equal to 〈R_r〉 = 3.99 and σR_r = 0.34, respectively.We identified cluster members using (1) absolute proper motions determined from individual-epoch positions of stars retrieved from IPHAS, 2MASS,URAT1, ALLWISE,UCAC5, and Gaia DR1 catalogs and positions of stars on individual Palomar Sky Survey plates reconstructed based on the data provided in USNO-B1.0 catalog and (2) absolute proper motions provided in Gaia DR2 catalog, and computed the averageGaia DR2 trigonometric parallaxes and propermotions of the clusters. Themean formal error of the inferred astrometric parallaxes of clusters is of about 7 μas, however, a comparison of astrometric and photometric parallaxes of our cluster sample implies that Gaia DR2 parallaxes are, on the average, systematically underestimated by 45 ± 9 μas. This result agrees with estimates obtained by other authors using other objects. At the same time, we find our photometric distance scale to be correct within the quoted errors (the inferred correction factor is equal to unity to within a standard error of 0.025).     

Systematic error of the Gaia DR1 TGAS parallaxes from data for the red giant clump

Based on the Gaia DR1 TGAS parallaxes and photometry from the Tycho-2, Gaia, 2MASS, andWISE catalogues, we have produced a sample of ~100 000 clump red giants within ~800 pc of the Sun. The systematic variations of the mode of their absolute magnitude as a function of the distance, magnitude, and other parameters have been analyzed. We show that these variations reach 0.7 mag and cannot be explained by variations in the interstellar extinction or intrinsic properties of stars and by selection. The only explanation seems to be a systematic error of the Gaia DR1 TGAS parallax dependent on the square of the observed distance in kpc: 0.18R ² mas. Allowance for this error reduces significantly the systematic dependences of the absolute magnitude mode on all parameters. This error reaches 0.1 mas within 800 pc of the Sun and allows an upper limit for the accuracy of the TGAS parallaxes to be estimated as 0.2 mas. A careful allowance for such errors is needed to use clump red giants as “standard candles.” This eliminates all discrepancies between the theoretical and empirical estimates of the characteristics of these stars and allows us to obtain the first estimates of the modes of their absolute magnitudes from the Gaia parallaxes: mode(M _H ) = ?1.49 ^m ± 0.04 ^m , mode(M _Ks ) = ?1.63 ^m ± 0.03 ^m , mode(M _W1) = ?1.67 ^m ± 0.05 ^m mode(M _W2) = ?1.67 ^m ± 0.05 ^m , mode(M _W3) = ?1.66 ^m ± 0.02 ^m , mode(M _W4) = ?1.73 ^m ± 0.03 ^m , as well as the corresponding estimates of their de-reddened colors.     

Extinction law at a distance up to 25 kpc toward the Galactic poles

Photometry from the Tycho-2, 2MASS, andWISE catalogues for clump and branch giants at a distance up to 25 kpc toward the Galactic poles has allowed the variations of various characteristics of the infrared interstellar extinction law with distance to be analyzed. The results obtained by the extinction law extrapolation method are consistent for different classes of stars and different characteristics as well as with previous studies. The conventional extinction law with a low infrared extinction is characteristic of only a thin layer no farther than 100 pc from the Galactic plane and of two thin layers near Z = ?600 and +500 pc. Far from the Galactic plane, in the Galactic halo, the infrared extinction law is different: the extinction in the Ks, W1, W2, W3, and W4 bands is, respectively, 0.17, 0.16, 0.16, 0.07, and 0.03 of the extinction in the V band. The accuracy of these coefficients is 0.03. If the extinction law reflects primarily the grain size distribution, then the fraction of large dust grains far from the Galactic plane is greater than that in the circumsolar interstellar medium.     

Kinematics of B-F Stars as a Function of Their Dereddened Color from Gaia and PCRV Data

Parallaxes with an accuracy better than 10% and proper motions from the Gaia DR1 TGAS catalogue, radial velocities from the Pulkovo Compilation of Radial Velocities (PCRV), accurate Tycho-2 photometry, theoretical PARSEC, MIST, YaPSI, BaSTI isochrones, and the most accurate reddening and interstellar extinction estimates have been used to analyze the kinematics of 9543 thin-disk B-F stars as a function of their dereddened color. The stars under consideration are located on the Hertzsprung–Russell diagram relative to the isochrones with an accuracy of a few hundredths of a magnitude, i.e., at the level of uncertainty in the parallax, photometry, reddening, extinction, and the isochrones themselves. This has allowed us to choose the most plausible reddening and extinction estimates and to conclude that the reddening and extinction were significantly underestimated in some kinematic studies of other authors. Owing to the higher accuracy of TGAS parallaxes than that of Hipparcos ones, the median accuracy of the velocity components U, V, W in this study has improved to 1.7 km s^?1, although outside the range ?0.1 ^m < (B _T ? V _T )₀ < 0.5 ^m the kinematic characteristics are noticeably biased due to the incompleteness of the sample. We have confirmed the variations in the mean velocity of stars relative to the Sun and the stellar velocity dispersion as a function of their dereddened color known from the Hipparcos data. Given the age estimates for the stars under consideration from the TRILEGAL model and the Geneva–Copenhagen survey, these variations may be considered as variations as a function of the stellar age. A comparison of our results with the results of other studies of the stellar kinematics near the Sun has shown that selection and reddening underestimation explain almost completely the discrepancies between the results. The dispersions and mean velocities from the results of reliable studies fit into a ±2 km s^?1 corridor, while the ratios σ _V /σ _U and σ _W /σ _U fit into ±0.05. Based on all reliable studies in the range ?0.1 ^m < (B _T ? V _T )₀ < 0.5^m, i.e., for an age from 0.23 to 2.4 Gyr, we have found: W_⊙ = 7.15 km s^?1, \({\sigma _U} = 16.0{e^{1.29({B_T} - {V_T})o}}\), \({\sigma _V} = 10.9{e^{1.11({B_T} - {V_T})o}}\), \({\sigma _W} = 6.8{e^{1.46({B_T} - {V_T})o}}\), the stellar velocity dispersions in km s^?1 are proportional to the age in Gyr raised to the power β _U = 0.33, β _V = 0.285, and β _W = 0.37.     

Spectral and photometric studies of polar CRTS CSS 130604 J 215427+155714

We present the results of spectroscopic and photometric studies of a new polar CRTS CSS130604 J 215427+155714, conducted at the telescopes of the SAO RAS. Analysis of the photometric series of observations allowed to clarify the orbital period of the system, P _o = 0_. ^d 0672879 (±0.0000003). We build radial velocity curves and trace the intensity variations in the Hβ and H_γ hydrogen lines and He II λ 4686 ?A ionized heliumline. Based on the Hβ and He II lines we build Doppler maps. It is shown that the line formation region is localized near the Lagrange point. The following parameter estimates of the system are obtained:M ₁ = 0.83 ± 0.10M _⊙, M ₂ = 0.15 ± 0.01M _⊙, q = M ₂/M ₁ = 0.18 ± 0.03, i = 53? ± 5?. Based on the results of spectral, photometric and previously published polarimetric observations the possible geometric model of the system is discussed.     

Quiescent and Active States of V1413 Aql I: Photometric Activity Criterion and the Detection of a Secondary Minimum

We present the results of our photometric UBV JHKL observations for the symbiotic star V1413 Aql obtained in 2012–2018. An analysis of the data has shown that inMay 2017 the system passed to a quiescent state with B ? V ≈ 0_? 6 for the first time since 1993. It lasted no more than five months. The J ? K color at the primary minimum of 2012 reached 1_? 5, which, given the interstellar reddening, corresponds to spectral type M5-M6 III of the cool component. A secondary minimum has been detected at φ ≈ 0.5 on the JK phase light curves constructed for the dates of observations with B ≥ 13.     

Independent estimate of the interstellar extinction toward FU Ori

Speckle-interferometric observations of FU Ori are performed with the 6-m telescope of the Special Astrophysical Observatory with 600/40 nm and 800/100 nm (central bandwidth/halfwidth) filters. The companion star FU Ori S that was recently discovered at λ >-1.25µm was recorded in observations with the λ/Δλ==800/100 nm filter. The positional parameters and magnitude difference of the companion in the filter considered are found to be θ = (163.9 ± 1.0)°, ρ = (0.493 ± 0.007)″, Δm = 3.96 ± 0.28. An analysis of the spectral energy distribution of the companion implies that for the extinction A _V toward FU Ori to be greater than about 1.6 ^m , i.e., the minimum value required by the available models of the fuor, the spectral type of the companion star must be no later than K3. The reliability of this conclusion and the possible ways for obtaining more accurate estimates of A _V are discussed.     

Results of a long-term monitoring of the multiple system SZ Cam

We present the results of the reduction of our photometric and spectroscopic observations for the eclipsing binary SZ Cam performed with the telescopes at the Astronomical Observatory of the Ural Federal University and the Special Astrophysical Observatory of the Russian Academy of Sciences in 1996–2014. Based on an 11-year-long photometric monitoring of SZ Cam, we have obtained new elements of its photometric orbit and parameters of its components. We have detected low-amplitude periodic light variations in SZ Cam that are possibly related to the ellipsoidal shape of the components of the spectroscopic binary third body. Based on published data and our new spectroscopy, we have found new values for the mass ratio, q = 0.72 ± 0.01, and parameters of the radial velocity curves of the components, V ₀ = ?3.6 ± 1.7 km s^?1, K ₁ = 190.2 ± 1.9 km s^?1, and K ₂ = 263.0 ± 2.4 km s^?1. The component masses have been estimated to be M ₁ = 16.1 M _⊙ and M ₂ = 11.6 M _⊙. We have obtained new light elements and parameters of the radial velocity curves for the third body, V ₀ ^3b = 4.2 ± 0.6 km s^?1 and K ₁ ^3b = 26.6 ± 0.8 km s^?1. We have improved the period of the relative orbit of SZ Cam and the third body, P _orb = 55.6 ± 1.5 yr.     

Catalog of candidates for quasars at 3 &lt; <Emphasis Type="Italic">z</Emphasis> &lt; 5.5 selected among X-Ray sources from the 3XMM-DR4 survey of the XMM-Newton observatory

We have compiled a catalog of 903 candidates for type 1 quasars at redshifts 3 < z < 5.5 selected among the X-ray sources of the “serendipitous” XMM-Newton survey presented in the 3XMMDR4 catalog (the median X-ray flux is ≈5 × 10^?15 erg s^?1 cm^?2 in the 0.5–2 keV energy band) and located at high Galactic latitudes |b| > 20° in Sloan Digital Sky Survey (SDSS) fields with a total area of about 300 deg². Photometric SDSS data as well infrared 2MASS and WISE data were used to select the objects. We selected the point sources from the photometric SDSS catalog with a magnitude error δ _mz′ < 0.2 and a color i′ ? z′ < 0.6 (to first eliminate the M-type stars). For the selected sources, we have calculated the dependences χ²(z) for various spectral templates from the library that we compiled for these purposes using the EAZY software. Based on these data, we have rejected the objects whose spectral energy distributions are better described by the templates of stars at z = 0 and obtained a sample of quasars with photometric redshift estimates 2.75 < z _phot < 5.5. The selection completeness of known quasars at z _spec > 3 in the investigated fields is shown to be about 80%. The normalized median absolute deviation (Δz = |z _spec ? z _phot|) is σ _Δz /(1+z _spec) = 0.07, while the outlier fraction is η = 9% when Δz/(1 + z _спек.) > 0.2. The number of objects per unit area in our sample exceeds the number of quasars in the spectroscopic SDSS sample at the same redshifts approximately by a factor of 1.5. The subsequent spectroscopic testing of the redshifts of our selected candidates for quasars at 3 < z < 5.5 will allow the purity of this sample to be estimated more accurately.     

Orbital parameters and variability of the emission spectrum for the massive binary system 103 Tau

Based on high-resolution spectra taken near the He I 6678 Å line for the massive binary system 103 Tau, we have detected a weak absorption component belonging to the binary’s secondary component. We have measured the radial velocities of both components, improved the previously known orbital parameters, and determined the new ones. The binary has an orbital period P _orb = 58.305^d, an orbital eccentricity e = 0.277, a radial velocity semi-amplitude of the bright component K _A = 44.8 km s^?1, and a component mass ratio M _A /M _B = 1.77. The absence of photometric variability and the estimates of physical parameters for the primary component suggest that the binary most likely has a considerable inclination of the orbital plane to the observer, i ≈ 50°?60°. In this case, the secondary component is probably a normal dwarf of spectral type B5–B8. Based on the spectra taken near the H _α line, we have studied the variability of the emission profile. It is shown to be formed in the Roche lobe of the secondary component, but no traces of active mass exchange in the binary have been detected.     

FG Sge at the stage of dust shell ejection

New photometric observations of the variable star FG Sge, a rapidly evolving planetary nebula nucleus, were performed in 2003–2008. On 230 nights, we obtained 86 UBV and 155 BV RI (or R _c , I _c ) magnitude estimates. The maximum amplitude of the V-band light variations was >8 ^m . Six deep minima and four high maxima were observed. Analysis of the light curve has shown that the pulsation period of the star remained constant since 1991 and was P = 115 days. We have studied the wavelength dependence of the extinction at various phases of the light curve. The blueing of the B-V color at deep minima is interpreted as the result of light scattering in the circumstellar dust shell of the star formed by preceding dust ejections since 1992. Our spectroscopic observations performed on nine nights in 2003–2007 with the 125-cm telescope at the Crimean Station of the Sternberg Institute have confirmed the previously detected intensity variations of the Swan bands and the sodium doublet with brightness. It is noted that the Swan bands originate in the upper atmosphere, the star’s extended envelope, while the sodium doublet originates mainly in the circumstellar shell of FG Sge. We suggest that the star is currently located in the temperature-luminosity diagram at the turning point of the horizontal track of cooling in the direction of hot stars—evolution caused by the last helium shell flash at the planetary nebula stage.     

Variability and rapid evolution of the protoplanetary object IRAS 18062+2410=V886 her

We present our long-term photometric and spectroscopic observations of a high-latitude B supergiant with an infrared excess—the protoplanetary nebula IRAS 18062+2410. OurU BV observations in 2000–2006 have confirmed the rapid irregular photometric variability of the star with a maximum amplitude as high as 0 _. ^m 4 in V that we found previously. The B—V and U—B color indices vary with amplitudes as high as 0 _. ^m 10 and 0 _. ^m 25, respectively, and show no clear correlation with the brightness. Our V-band CCD observations on 11 nights in 2006 have revealed brightness trends during the night. The variability of IRAS18062+2410 is similar in pattern to the light variations in other hot post-AGB objects and some of the nuclei of young planetary nebulae. We assume that pulsations and a variable stellar wind can be responsible for the variability of these stars. In addition to the rapid variability, our 12-year-long observations have revealed a systematic decline in the mean brightness of IRAS 18062+2410. This may be related to a rise in the temperature of the star at constant luminosity as a result of its evolution. Low-resolution spectroscopic observations have shown a systematic increase in the equivalent widths of the Hα, Hβ, [NII]λ6584 Å, OI λ8446 Å, and [OII] λ7320–7330 Å emission lines. The changes in the star’s emission line spectrum are probably caused by an increase in the degree of ionization of the gas shell due to a rise in the temperature of the ionizing star. Our photometric and spectroscopic observations of IRAS 18062+2410 confirm the previously made assumptions that the star evolves very rapidly to the region of planetary nebulae.     

ASTRONIRCAM—the infrared camera-spectrograph for the 2.5-m telescope of SAI Caucasian observatory

ASTRONIRCAM is a cryogenic-cooled slit camera-spectrograph for the spectral range 1–2.5 μm installed at the Nasmyth focus of the 2.5-meter telescope of the Caucasian observatory of the Sternberg Astronomical Institute of Lomonosov Moscow State University. The instrument is equipped with a HAWAII-2RG 2048×2048 HgCdTe array. Grisms are used as dispersive elements. In the photometric mode ASTRONIRCAM allows for extended astronomical object imaging in a 4.′6 × 4.′6 field of view with a 0.269 arcsec/pixel scale in standard photometric bands J, H, K, and K _s as well as in the narrow-band filters centered on the lines CH₄, [Fe II], H₂ v=1-0 S(1), Br _γ , and CO. In the spectroscopic mode, ASTRONIRCAM takes spectra of extended or point-like sources with a spectral resolution of R = λ/Δλ ≤ 1200. The general design, optical system, detector electronics and readout, amplification and digitization schemes are considered. The GAIN conversion factor measurement results are described as well as its dependence on the accumulated signal (nonlinearity).The full transmission of the atmosphere-to-detector train ranges from 40 to 50% in the wide-band photometry mode. The ASTRONIRCAMsensitivity at the 2.5-m telescope is characterized by the limiting J = 20, K = 19 stellar magnitudes measured with a 10% precision and 15 minute integration for 1″ atmospheric seeing conditions. References to the first results based on ASTRONIRCAM observations are given.     

Correlation function of quasars from SDSS DR3

We calculate the parameters of the two-point correlation function of quasars w(r) = (r _c /r) ^γ on the basis of the SDSS DR3 data. The correlation functions are first determined from projected distances with the use of a special technique for compiling randomized catalogs. Next the parameters of the spatial correlation function are obtained with the assumption of local isotropy. For the quasars with redshifts z = 0.8–2.1, we obtained the estimates γ = 1.76 ± 0.14, r _c = 6.60 ± 0.85 h ^?1 Mpc in the comoving distance range 2–30 Mpc and γ = 1.90 ± 0.11, r _c = 6.95±0.57 h ^?1 Mpc in the range 2–50 Mpc. These estimates agree, within the limits of errors, with the estimates obtained for the redshifts 0.4 < z < 2.1. The original catalog shows some deficit of pairs with separations less than 1 Mpc.     

Spectroscopic studies of yellow supergiants in the Cepheid instability strip

High-resolution spectra of nine yellow nonvariable supergiants (NVSs) located within the canonical Cepheid instability strip from Sandage and Tammann (1969) (α Aqr, ? Leo, μ Per, ω Gem, BD+60 2532, HD 172365, HD 187299, HD 190113, and HD 200102) were taken with the 1-m Zeiss and 6-m BTA telescopes at the Special Astrophysical Observatory of the Russian Academy of Sciences in the 1990s. These have been used to determine the atmospheric parameters, chemical composition, radial velocities, reddenings, luminosities, distances, and radii. The spectroscopic estimates of T _eff and the luminosities determined from the Hipparcos parallaxes have shown eight of the nine program NVSs on the T _eff?log(L/L _⊙) diagram to be outside the canonical Cepheid instability strip. When the edges of the Cepheid instability strip from Bono et al. (2000) are used, out of the NVSs from the list on the diagram one is within the Cepheid instability strip but closer to the red edge, two are at the red edge, three are beyond the red edge, two are at the blue edge, and one is beyond the blue edge. The evolutionary masses of the objects have been estimated. The abundances of α-elements, r- and s-process elements for all program objects have turned out to be nearly solar. The СNO, Na, Mg, and Al abundance estimates have shown that eight of the nine NVSs from the list have already passed the first dredge-up. Judging by the abundances of the key elements and its position on the T _eff?log(L/L _⊙) diagram, the lithium-rich supergiant HD 172365 is at the post-main-sequence evolutionary stage of gravitational helium core contraction and moves toward the first crossing of the Cepheid instability strip. The star ? Leo should be assigned to bright supergiants, while HD 187299 and HD 190113 may have already passed the second dredge-up and move to the asymptotic branch.     

Emission-line galaxies from SDSS DR4: Statistical studies of the current star formation

For a sample of 8156 emission-line galaxies from the Sloan Digital Sky Survey Data Release 4 (SDSS DR4), we have determined the current star formation rates (SFR) from three parameters: the H_α luminosity of H II regions corrected for the aperture and interstellar extinction (N = 7006 galaxies), the far-infrared luminosity (IRAS data, N = 350), and the monochromatic luminosity in the radio continuum at ν = 1.4 GHz (NVSS data, N = 475). A Salpeter initial mass function with the range of stellar masses 0.1–100 M _⊙ was assumed in the SFR _FIR calculations. In calculating SFR_1.4, we assumed that the fraction of the thermal emission in the total radio continuum emission of the galaxy at 1.4 GHz was 10%. An upper limit for the starburst age has been determined for galaxies with known abundances of heavy elements. We compare our results with those of similar studies for isolated and Markarian H II galaxies.