Spectroscopy and photometry of the protoplanetary nebula candidate stHα62 = IRAS 07171+1823

We present the results of spectroscopic and photometric observations for the B star StHα62 with an IR excess, a post-AGB candidate identified with the IR source IRAS 07171+1823. High-resolution spectroscopy has allowed the λ4330–7340 Å spectrum of the star to be identified: it contains absorption lines of an early B star and emission lines of a gaseous shell. The residual line intensities have been measured. The heliocentric radial velocities measured from absorption lines of the star and emission lines of the shell are 〈V _r 〉 = +45 ± 1 and +52 ± 1 km s^?1, respectively. The line-of-sight velocities of gas-dust clouds determined from the interstellar Na I lines are 12 and 33 km s^?1. The He I λ5876 Å line exhibits a P Cyg profile, which is indicative of an ongoing mass loss by the star. The expansion velocity of the outer shell estimated from forbidden lines is 12–13 km s^?1. Quantitative classification gives the spectral type B0.51 for the star. The parameters of the gaseous shell have been determined: N _e = 3.1 × 10³ cm^?3 and T _e ～ 21 000 K. Over 4 years of its observations, the star showed rapid irregular light variations with the amplitudes ΔV = We present the results of spectroscopic and photometric observations for the B star StHα62 with an IR excess, a post-AGB candidate identified with the IR source IRAS 07171+1823. High-resolution spectroscopy has allowed the λ4330–7340 ? spectrum of the star to be identified: it contains absorption lines of an early B star and emission lines of a gaseous shell. The residual line intensities have been measured. The heliocentric radial velocities measured from absorption lines of the star and emission lines of the shell are 〈V _r 〉 = +45 ± 1 and +52 ± 1 km s⁻¹, respectively. The line-of-sight velocities of gas-dust clouds determined from the interstellar Na I lines are 12 and 33 km s⁻¹. The He I λ5876 ? line exhibits a P Cyg profile, which is indicative of an ongoing mass loss by the star. The expansion velocity of the outer shell estimated from forbidden lines is 12–13 km s⁻¹. Quantitative classification gives the spectral type B0.51 for the star. The parameters of the gaseous shell have been determined: N _e = 3.1 × 10³ cm⁻³ and T _e ∼ 21 000 K. Over 4 years of its observations, the star showed rapid irregular light variations with the amplitudes ΔV = , ΔB = , and ΔU = and no color-magnitude correlation. We estimate the total extinction for the star from our photometric observations as A _v = . Near-IR observations have revealed dust radiation with a temperature of ∼1300 K. We estimate the distance to StHα62 to be r = 5.2 ± 1.2 kpc by assuming that the star is a low-mass (M = 0.55 ± 0.05 M _⊙) protoplanetary nebula. Original Russian Text ? V.P. Arkhipova, V.G. Klochkova, E.L. Chentsov, V.F. Esipov, N.P. Ikonnikova, G.V. Komissarova, 2006, published in Pis’ma v Astronomicheskiĭ Zhurnal, 2006, Vol. 32, No. 10, pp. 737–747.     

Hα profile variations in the spectrum of the supergiant HD14134

Variations of the Hα line in the spectra of the star HD14134 are investigated using observations carried out in 2013–2014 and in 2016 with the 2-m telescope at Shamakhy Astrophysical Observatory.In the spectra of this star,the absorption and emission components of Hα are found to disappear and an inverse P Cyg profile of Hα is seen on some observational epochs.Our observations showed that when the Hα line disappeared or an inversion of the P-Cyg-type profile is observed in the spectra,the Hβ line is redshifted.When these events appeared,no synchronous variabilities were observed in the spectral parameters of other spectral lines formed in deeper atmospheric layers.In addition,the structures of Hα,CII(6578.05 ,6582.88 ),SiII(6347.1 ,6371.36 ) and Hβ lines are variable on a timescale of hours,but we did not detect significant variations in the other photospheric lines,as well as in the HeI(5875.72 ) line.It is suggested that observational evidence for the non-stationary atmosphere of HD14134 can be associated in part with non-spherical stellar wind.     

Searches for HH objects in star formation regions. VII. Herbig-Haro objects in the region of the nebula GM 2–41

Five new Herbig-Haro objects (HH 1036–1040) have been discovered in the neighborhood of the nebula GM 2–41 in a region with an area of 14′ × 14′, at the center of the HII region DR 15 located in the southern periphery of the Cyg OB2 association. Four of them have a complex structure typical of HH flows. Hydrogen molecular emission is detected in the object HH 1036 using archived images from the Spitzer telescope. Two new infrared nebulae illuminated by very red young stellar objects are also found.     

Disk precession and quasi-periodic brightness oscillations of V603 Aql in 2001–2002

We present the photometric observations of the old nova V603 Aql with the RTT 150 Russian-Turkish telescope during eleven nights of 2001–2002. We show that the star at this time was in a state with positive superhumps and its photometric period of \(0\mathop .\limits^d 144 - 0\mathop .\limits^d 145\) was longer than the orbital period. We found night-to-night variations in the mean brightness of the system that are consistent with disk precession periods of \(3\mathop .\limits^d 3\) and \(3\mathop .\limits^d 0\) in 2001 and 2002, respectively. Analysis of the results and their comparison with the results of other authors using current theoretical models for disk precession lead us to suggest that the change in the disk precession period was caused by a change in the accretion rate in the system. V603 Aql in a state with negative superhumps was found to be brighter than it is in a state with positive superhumps by \(0\mathop .\limits^m 2 - 0\mathop .\limits^m 3\). We hypothesize that the transition between these states could also be caused by a change in the accretion rate. Quasi-periodic oscillations (QPOs) of the brightness with typical time scales of 9–70 min were detected on each observing night. These time scales were found to change from night to night. The detection of QPOs with a period of about 0.05 of the orbital period and its multiples on certain nights provides evidence for the model of QPO generation through accretion-rate modulation by ionization-front oscillations on the surface of the donor star near the inner Lagrangian point.     

Photometric variability and spectral features of the protoplanetary nebula LSII + 34° 26 = V1853 Cyg

We present photoelectric and spectroscopic observations of the protoplanetary object V 1853 Cyg, a B supergiant with an IR excess. Over two years of its observations, the star exhibited rapid irregular light variations with amplitudes $\Delta V = 0\mathop .\limits^m 3$ , $\Delta B = 0\mathop .\limits^m 3$ , $\Delta U = 0\mathop .\limits^m 4$ and no correlation between color and magnitude. Its mean magnitude has not changed since the first UBV observations in 1973 (Drilling 1975). Low-resolution spectroscopic observations show that the spectrum of V 1853 Cyg in 2000 corresponded to that of a B1–B2 star with T _eff ～ 20000 K. High-resolution spectroscopic observations confirm the conclusion that the profiles of absorption and emission lines are variable. We identified the star’s spectral lines and measured the equivalent widths of more than 40 lines. The star’s radial velocity is 〈V _r 〉= ?49 × 5 km s^?1, as measured from absorption lines, and ranges from–50 to–85 km s^–1 for different lines, as measured from shell emission lines. The velocity of the dust clouds on the line of sight determined from diffuse interstellar bands (DIBs) and from interstellar Na I lines is 〈V _r 〉= ?16 × 5 km s^?1. The P Cyg profiles of the He I λ5876 Å and λ6678 Å lines suggest an ongoing mass loss by the star. An analysis of the observational data confirms the conclusion that the star belongs to the class of intermediatemass protoplanetary objects.     

Infrared photometry of the symbiotic novae V1016 Cyg and HM Sge in 1978–1999

The photometric JHKLM observations of the symbiotic novae V1016 Cyg and HM Sge in 1978–1999 are presented. Parameters of the cool stars themselves and the dust envelopes are estimated. The periods of 470±5 days (for V1016 Cyg) and 535±5 days (for HM Sge) are reliably determined from the entire set of our photometric J data for V1016 Cyg and HM Sge. In addition, monotonic light and color variations are observed on a time scale of several thousand days, with the increase in infrared brightness occurring with the simultaneous decrease in infrared color indices; i.e., the dust envelopes in which both components of the systems were embedded before the outburst of their hot sources in 1964 and 1975, respectively, had continued to disperse until late 1999. The amplitudes of these variations for HM Sge are almost twice those for V1016 Cyg. For HM Sge, the dust envelope reached a maximum density near JD 2447500 and then began to disperse. In the case of V1016 Cyg, a maximum density of the dust envelope was probably reached near JD 2444800, and its dispersal has been continuing for about 20 years. Thus, in both symbiotic novae, their dust envelopes reached a maximum density approximately eight years after the outburst of the hot component and then began to disperse. An analysis of the color-magnitude (J–K, J) diagram reveals that grains in the dust envelopes of V1016 Cyg and HM Sge are similar in their optical properties to impure silicates. The observed [J–K, K–L] color variations for the symbiotic novae under study can be explained in terms of the simple model we chose by variations in the Mira's photospheric temperature from 2400 to 3000 K and in the dust-envelope optical depth from 1 to 3 at a wavelength of 1.25 µm for a constant grain temperature. The observed J–K and K–L color indices for both symbiotic novae, while decreasing, tend to the values typical of Miras. The dust envelopes of both symbiotic novae are optically thick. The dust envelope around HM Sge is, on the average, twice as dense as that around V1016 Cyg; the Mira in V1016 Cyg is slightly cooler (~2800–2900 K) than that in HM Sge (~2600–2700 K). The dust-envelope density decreases as the Mira's temperature increases. The absolute bolometric magnitudes are $ - 5\mathop .\limits^m 1 \pm 0\mathop .\limits^m 15$ for V 1016 Cyg and $5\mathop .\limits^m 27 \pm 0\mathop .\limits^m 17$ for HM Sge. Their distances are 2.8±0.6 and 1.8±0.4 kpc, respectively; the luminosities and radii of their cool components (Miras) are 8.6×10³ L _⊙, 1×10⁴ L _⊙, 500R _⊙, and 540R _⊙. The radii of their dust envelopes are 1400R _⊙ and 1500R _⊙; the masses are (3?3.3) × 10^?5M_⊙ and (4?8) × 10^?5M_⊙ The dust envelope of V1016 Cyg disperses slower than that of HM Sge by almost a factor of 25.     

HUDF 1619—A candidate for polar-ring galaxies in the Hubble Ultra Deep Field

A galaxy that is a good candidate for polar-ring galaxies has been detected in the Hubble Ultra Deep Field (HUDF). The galaxy HUDF 1619 (V ≈ 25 ^m , z ～ 1) is the most distant object of this type known to date. A large-scale structure crosses the highly warped disk of the main galaxy seen almost edge-on at an angle of about 70°. The luminosity of this structure (the possible polar ring) reaches ～1/3 of the luminosity of the central galaxy. A strong absorption lane is seen in the region where this structure is projected onto the disk of the central object. There are two galaxies of comparable luminosity adjacent to HUDF 1619 (in projection). One of them may be the donor galaxy the interaction with which gave rise to the ring structure.     

Spectral observations of FBS blue stellar objects in the zone δ = + 35°

The next list of spectral data on blue stellar objects (BSOs) is presented. 58 FBS objects in a zone with a central declination δ = + 35° were observed with the 2.6-m telescope at the Byurakan Observatory during 1990–1991. In addition, 3 objects were observed (3 CCD spectra were obtained) with the BAO 2.6-m and OHP 1.93-m telescopes in 1997–2000 using modern instrumentation. 9 white dwarfs, 47 hot subdwarfs, and 2 HBB stars have been discovered. Spectra of the 10 most interesting objects are given. __________ Translated from Astrofizika, Vol. 51, No. 2, pp. 277–283 (May 2008).     

A comparison between the precession–nutation variations in right ascension referred to the CIO and the equinox

The article analyzes the precession–nutation variations in right ascension of stars after the introduction Celestial Intermediate Origin (CIO) as a new origin of the right ascensions. It points out that changes in right ascension depend not only on the motion of the origin, but also on the changes of the pole and hour circles, depending on the position of stars. This explains the apparent paradox that, for certain groups of stars, despite the almost complete elimination of the precession and nutation motion of the CIO on the equator, the magnitude of the variations in right ascension related to the CIO can exceed the magnitude of the classic variations referred to the equinox.     

Infrared photometry for variable stars of selected types in 1978–1999

We present and discuss IR observations for 35 stars of different variability types averaged over many years. These include about twenty symbiotic stars, four W Ser stars and one Algol, six Miras, etc.     

Identification of absorption lines of rare-earth elements in the region of the spectrum λλ 610.25–610.57 nm roAp stars,HD 101065, HD 134214, HD 137949, and HD 24712

In the spectral region λλ = 610.25−610.57 nm of the roAp star HD 101065, we performed the identification of the rare-earth element absorption lines absent from the atomic spectral line databases VALD and DREAM. The identified lines were used for calculating the synthetic spectra of the roAp stars HD 137949, HD 134214, and HD 24712. The upper limit of the identified line estimates was determined. The rotation/pulsation parameter νsini and magnetic field modulus were determined using the lines Nd III 669.083 nm and Ca I 616.217 nm. The element abundance in the roAp stars HD 134214 and HD 24712 was determined for the first time using Nd III lines. Calculations were carried out with the help of the code SynthM developed by S.A. Khan.     

Martian CO abundance from the J = 1 → 0 rotational transition: Evidence for temporal variations

Mars was observed in the CO (J = 1 → 0) 2.6-mm wavelength line between 29 March and 1 April, 1980. The data were analyzed using a model atmosphere based on Viking measurements. A least-squares fit of the model to the observed line profile yielded an average CO mixing ratio of (3.2 ± 1.1) × 10^?3. This value is four times larger than that obtained by L. D. Kaplan, J. Connes, and P. Connes, 1969 (Astrophys. J.157, L187-L195) from analysis of an infrared spectrum obtained in 1967 by J. Connes, P. Connes, and J. P. Maillard, 1969 (Atlas of Near Infrared Spectra of Venus, Mars, Jupiter, and Saturn, Centre National de la Recherche Scientifique, Paris). Models of the Martian atmospheric chemistry indicate that this implied temporal variation could easily exist and that it would be due primarily to variations in the abundance of H₂O.     

Morphology of the Light Curves for the X-ray Novae H 1743-322 and GX 339-4 during Their Outbursts in 2005–2019

Astronomy Letters - Based on long-term SWIFT, RXTE, and MAXI observations of the X-ray novae H 1743-322 (IGR J17464-3213) and GX 339-4, we have investigated the morphology and classified the light...     

UBVRI photometry of the eclipsing symbiotic system CI Cygni in 1996–1999

The UBVRI photometry of the eclipsing symbiotic star CI Cyg in 1996–1999 is presented. The system continued to be in quiescence during this period. The shape of the minima in its light curves attributable to eclipses of the compact star with an accretion disk by the red giant is the same as that in 1988–1995. An analysis of our observations and those of other researchers, which span a total of 27 years, has revealed a cyclic variability of the out-of-eclipse photometric properties of CI Cyg on a time scale of about 10.7±0.6 years with the clearest manifestation in the U-B color. The fact that the system’s out-of-eclipse light variations in U, on the one hand, and in BVRI, on the other, occur in antiphase suggests that the titanium red giant plays a significant role in this cyclic process. However, with its contribution to the total U flux being no larger than 10%, the observed light fluctuations of CI Cyg in this band must be caused not only by variability of the giant but also by light variations of the hot component. The presence of a 10.7-year cycle in the system’s active and quiescent states suggests that some precession phenomenon is responsible for it. Precession of the accretion disk, which would cause both the observed brightness of the primary component and the effect of its radiation on the titanium red giant to vary, can serve as an example of such a phenomenon.     

Infrared photometry of Sakurai’s object (V4334 Sgr) in 1996–1999

The infrared photometric observations of V4334 Sgr in 1996–1999 are presented. Together with optical data, they have allowed us to accurately estimate the bolometric flux from this star and to investigate the structure of its dust envelope over the above period. The star is shown to have passed through four well-defined stages in these four years as it moved backward along the post-AGB track, and it now appears to have started moving forward after a halt. At the first stage (1996), there was no dust in the star’s envelope. Its visual brightness slightly increased, and it reddened in the entire observed spectral range. The bolometric flux also gradually rose. At the second stage (1997), an optically thick dust envelope condensed around the star, which, however, essentially did not manifest itself at optical wavelengths. The bolometric flux continued to rise through an increase in the star’s infrared brightness alone; the rate of its rise also increased. At the third stage (1998–March 1999), V4334 Sgr entered the R CrB phase. First two shallow minima and then two deep minima were observed at optical wavelengths. The star appreciably reddened during the deep minima. The bolometric flux ceased to rise and began to gradually fall in the second half of 1998. At the fourth stage (since March 1999 up until now), V4334 Sgr has been at a protracted deep minimum, which is atypical of the R CrB stars. The bolometric flux between March and October underwent no significant variations. We describe the structure of the dust envelope around V4334 Sgr since its formation. From June 1997 until July 1998, the optical depth of the dust shell, its inner and outer radii, and its mass increased by factors of ～2.2, ～2.0, 2.3, and ～10, respectively. In July 1998, τ(V)≈2.3, R _{d, in}≈7.4×10¹⁴ cm, R _{d, in}/R _{d, out}≈0.7(R _{d, in}/R _*≈47), and M _dust≈1.6×10^?7 M _⊙.     

Linear size–extended radio luminosity (D–P E ) correlation in BL Lacertae objects: evidence for large scale beaming?

In this paper, we use the distributions of projected linear size (D), core- (P _C ) and extended- (P _E ) radio luminosities, to investigate a consequence of relativistic beaming and radio source orientation scenario for low-luminosity extragalactic radio sources. In this scenario, BL Lacertae objects (BL Lacs) are believed to be Fanaroff-Riley type I (FR I) radio galaxies, but with radio axes aligned close to the line of sight. At this orientation, the core emission is greatly enhanced by relativistic Doppler boosting and linear size foreshortened due to geometrical projection. A simple outcome of this scenario is that the extended luminosity is expected to be orientation invariant, but a D–P _C correlation is envisaged. Results show that both the relative core dominance (R) and linear size are strongly correlated with extended luminosity (r≥ 0.7). Using the R-distribution and R–P _E anti-correlation, we show that the difference in radio core-dominance between FR I radio galaxies and X-ray selected BL Lacs can be accounted for by a bulk Lorentz factor γ～5–13 and viewing angle ?～5–15^°, which can be understood in terms of the scenario, with relativistic beaming persisting at largest scales.     

“Anti-glitches” in the Quark–Nova model for AXPs I

In the Quark–Nova model, Anomalous X-ray Pulsars (AXPs) are quark stars surrounded by a degenerate iron-rich Keplerian ring (a few stellar radii away). AXP bursts are caused by accretion of chunks from the inner edge of the ring following magnetic field penetration. For bright bursts, the inner disk is prone to radiation induced warping which can tilt it into counter-rotation (i.e. retrograde). For AXP 1E2259+586, the 2002 burst satisfies the condition for the formation of a retrograde inner ring. We hypothesize the 2002 burst reversed the inner ring setting the scene for the 2012 outburst and “anti-glitch” when the retrograde inner ring was suddenly accreted leading to the basic observed properties of the 2012 event.