- ID:
- ivo://CDS.VizieR/J/A+AS/128/245
- Title:
- Photometry of chemically peculiar stars
- Short Name:
- J/A+AS/128/245
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Differential Stroemgren uvby photometric observations from the Four College Automated Photoelectric Telescope are presented for four Chemically Peculiar stars of the upper main sequence: the HgMn star binary AR Aurigae and the magnetic stars 3 Hydrae, 49 Cancri, and BX Bootis. AR Aurigae shows little variability except during the primary and secondary eclipses. The 11.305 day period of Maitzen et al. for 3 Hya is confirmed. A new period of 7.0501 days is found for 49 Cancri while a slightly refined period of 2.88756 days is derived for BX Boo.
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- ID:
- ivo://CDS.VizieR/J/PASP/109/9
- Title:
- Photometry of chemically peculiar stars
- Short Name:
- J/PASP/109/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Differential Stromgren uvby photometric observations from the Four College Automated Photoelectric Telescope of four magnetic Chemically Peculiar stars are used to refine rotational periods and to define the shapes of the light curves. HR 1643 (P=2.73475d) shows large phase variability in all four magnitudes. Theta Aur (P=3.6188d) exhibits large amplitude variations with two components contributing to the minima. For 49 Cam (P=4.28679d), we probably are observing both polar regions and much of the surface. The values for HR 3724 (P=33.984d) confirm Wolff's result that the main variability is in v.
2783. Photometry of CU Vir
- ID:
- ivo://CDS.VizieR/J/A+A/625/A34
- Title:
- Photometry of CU Vir
- Short Name:
- J/A+A/625/A34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CU Vir has been the first main sequence star that showed regular radio pulses that persist for decades, resembling the radio lighthouse of pulsars and interpreted as auroral radio emission similar to that found in planets. The star belongs to a rare group of magnetic chemically peculiar stars with variable rotational period. We study the ultraviolet (UV) spectrum of CU Vir obtained using STIS spectrograph onboard the Hubble Space Telescope (HST) to search for the source of radio emission and to test the model of the rotational period evolution. We used our own far-UV and visual photometric observations supplemented with the archival data to improve the parameters of the quasisinusoidal long-term variations of the rotational period. We predict the flux variations of CU Vir from surface abundance maps and compare these variations with UV flux distribution. We searched for wind, auroral, and interstellar lines in the spectra. The UV and visual light curves display the same long-term period variations supporting their common origin. New updated abundance maps provide better agreement with the observed flux distribution. The upper limit of the wind mass-loss rate is about 10^-12^M_{sun}_/yr. We do not find any auroral lines. We find rotationally modulated variability of interstellar lines, which is most likely of instrumental origin. Our analysis supports the flux redistribution from far-UV to near-UV and visual domains originating in surface abundance spots as the main cause of the flux variability in chemically peculiar stars. Therefore, UV and optical variations are related and the structures leading to these variations are rigidly confined to the stellar surface. The radio emission of CU Vir is most likely powered by a very weak presumably purely metallic wind, which leaves no imprint in spectra.
- ID:
- ivo://CDS.VizieR/J/A+A/588/A63
- Title:
- Photometry of DBS 77-78-102-160-161 regions
- Short Name:
- J/A+A/588/A63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report a study of the global properties of some embedded clusters placed in the fourth quadrant of the MilkyWay to clarify some issues related with their location into de Galaxy and their stellar formation processes. We performed BVI photometric observations in the region of DBS 77, 78, 102, 160, and 161 clusters and infrared spectroscopy in DBS 77 region. They were complemented with JHK data from VVV survey combined with 2MASS catalogue, and used mid-infrared information from GLIMPSE catalogue. We also searched for HI data from SGPS and PMN radio surveys, and previous spectroscopic stellar classification. The spectroscopic and photometric information allowed us to estimate the spectral classification of the brightest stars of each studied region. On the other hand, we used the radio data to investigate the interstellar material parameters and the continuum sources probably associated with the respective stellar components. We estimated the basic physical parameters of the clusters (reddening, distance, age, and initial mass function). We searched for HII regions located near to the studied clusters and we analyzed the possible link between them. In the particular case of DBS 160-161 clusters, we identified the HI bubble B332.5-0.1-42 located around them. We found that the mechanical energy injected to the interstellar medium by the more massive stars of this couple of clusters was enough to generate the bubble.
- ID:
- ivo://CDS.VizieR/J/other/RMxAA/53.235
- Title:
- Photometry of 6 deep-contact W UMa
- Short Name:
- J/other/RMxAA/53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometric observations in Sloan g' and i' bands of W UMa binaries V0637 Peg, V0473 Cam, CSS J153314.8+560527, CSS J075258.0+382035, V0416 Gem and NSVS 6859986 are presented. Their periods are in the range of 0.26-0.43d. The light curve solutions revealed that the components of each target are almost equal in temperature. The stellar components are of G and K spectral types and undergo total eclipses. All targets have deep-contact configurations with fillout factor f>=0.5. NSVS 6859986 has one o f the biggest value determined until now, f=0.84. We studied the empirical dependencies of fillout factor on the stellar parameters (temperature, period, mass ratio, relative component radii, and luminosity ratio) for a sample of around thirty stars. They are consistent with the theoretical predictions but there are deviations from the common trends.
- ID:
- ivo://CDS.VizieR/J/A+A/602/A99
- Title:
- Photometry of EXors from Asiago plates
- Short Name:
- J/A+A/602/A99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- EXor objects are young variables that show episodic variations of brightness commonly associated to enhanced accretion outbursts. With the aim of investigating the long-term photometric behaviour of a few EXor sources, we present here data from the archival plates of the Asiago Observatory, showing the Orion field where the three EXors V1118, V1143, and NY are located. A total of 484 plates were investigated, providing a total of more than 1000 magnitudes for the three stars, which cover a period of about 35yrs between 1959 to 1993. We then compared our data with literature data. Apart from a newly discovered flare-up of V1118, we identify the same outbursts already known, but we provide two added values: (i) a long-term sampling of the quiescence phase; and (ii) repeated multi-colour observations (BVRI bands). The former allows us to give a reliable characterisation of the quiescence, which represents a unique reference for studies that will analyze future outbursts and the physical changes induced by these events. The latter is useful for confirming whether the intermittent increases of brightness are accretion-driven (as in the case of V1118), or extinction-driven (as in the case of V1143). Accordingly, doubts arise about the V1143 classification as a pure EXor object. Finally, although our plates do not separate NY Ori and the star very close to it, they indicate that this EXor did not undergo any major outbursts during our 40yrs of monitoring.
- ID:
- ivo://CDS.VizieR/J/PAZh/35/592
- Title:
- Photometry of FG Sge at the ejection state
- Short Name:
- J/PAZh/35/592
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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 BVRI (or Rc, Ic) magnitude estimates. The maximum amplitude of the V-band light variations was >8mag. Six deep minima and four high maxima were observed.
- ID:
- ivo://CDS.VizieR/J/A+A/374/1049
- Title:
- Photometry of FK Com for 1993-2001
- Short Name:
- J/A+A/374/1049
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report 8 years of previously unpublished photometric observations of FK Com. The observations have been carried out between 1993 and 2001 with six different telescopes: 60 cm at Mt. Maidanak (Tashkent, Uzbekistan), Phoenix 10, Wolfgang and Amadeus located in Arizona, USA, and 20cm and 60 cm KVA on La Palma, Spain. Observations contain measurements at the following bands: Johnson U, B, V and R, Bessel R, Cousins I and Stromgren b and y. The observations are differential photometry in respect to the primary comparison star HD 117567. NOTE: Table 1 in the paper contains some small misprints in the Julian dates. Also for Wolfgang and Amadeus the number of observations given in Table1 at each band is slightly less than actually given in Table2c and Table2d. This is caused by accidentally using a limiting error of 0.01 in magnitudes when creating Table 1. In Table 2 the limiting error for Wolfgang and Amadeus is 0.02 mag, as mentioned in the paper itself. In Table2a-e 99.0000 means that no observations were available at that time at that band or that the error in the magnitude was larger than 0.02.
- ID:
- ivo://CDS.VizieR/J/ApJ/742/116
- Title:
- Photometry of four massive transiting exoplanets
- Short Name:
- J/ApJ/742/116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of four relatively massive (2-7M_J_) transiting extrasolar planets. HAT-P-20b orbits the moderately bright V=11.339 K3 dwarf star GSC 1910-00239 on a circular orbit, with a period P=2.875317+/-0.000004 days. The planetary companion has a mass of 7.246+/-0.187M_J_ and a radius of 0.867+/-0.033R_J_ yielding a mean density of 13.78+/-1.50g/cm^3^. HAT-P-21b orbits the V=11.685 G3 dwarf star GSC 3013-01229 on an eccentric (e=0.228+/-0.016) orbit, with a period P=4.124481+/-0.000007 days. The planetary companion has a mass of 4.063+/-0.161M_J_ and a radius of 1.024+/-0.092R_J_ yielding a mean density of 4.68^+1.59^_-0.99_g/cm^3^. HAT-P-21b is a borderline object between the pM and pL class planets, and the transits occur near apastron. HAT-P-22b orbits the bright V=9.732 G5 dwarf star HD 233731 on a circular orbit, with a period P=3.212220+/-0.000009 days. The planet has a mass of 2.147+/-0.061M_J_ and a compact radius of 1.080+/-0.058R_J_ yielding a mean density of 2.11^+0.40^_-0.29_g/cm^3^. The host star also harbors an M-dwarf companion at a wide separation. Finally, HAT-P-23b orbits the V=12.432 G0 dwarf star GSC 1632-01396 on a close to circular orbit, with a period P=1.212884+/-0.000002 days. The planetary companion has a mass of 2.090+/-0.111M_J_ and a radius of 1.368+/-0.090R_J_ yielding a mean density of 1.01+/-0.18g/cm^3^. HAT-P-23b is an inflated and massive hot Jupiter on a very short period orbit, and has one of the shortest characteristic infall times (7.5^+2.9^_-1.8_Myr) before it gets engulfed by the star.
- ID:
- ivo://CDS.VizieR/J/ApJ/779/65
- Title:
- Photometry of LBGs, LAEs and GNBs at z~2.85
- Short Name:
- J/ApJ/779/65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a survey for z~2.85 Lyman-continuum (LyC) emission in the HS1549+1933 field and place constraints on the amount of ionizing radiation escaping from star-forming galaxies. Using a custom narrowband filter (NB3420) tuned to wavelengths just below the Lyman limit at z>=2.82, we probe the LyC spectral region of 49 Lyman break galaxies (LBGs) and 91 Ly{alpha} emitters (LAEs) spectroscopically confirmed at z>=2.82. Four LBGs and seven LAEs are detected in NB3420. Using V-band data probing the rest-frame nonionizing UV, we observe that many NB3420-detected galaxies exhibit spatial offsets between their LyC and nonionizing UV emission and are characterized by extremely blue NB3420-V colors, corresponding to low ratios of nonionizing to ionizing radiation (F_UV_/F_LyC_) that are in tension with current stellar population synthesis models. We measure average values of (F_UV_/F_LyC_) for our LBG and LAE samples, correcting for foreground galaxy contamination and H I absorption in the intergalactic medium. We find (F_UV_/F_LyC_)_corr_^LBG^=82+/-45 and (F_UV_/F_LyC_)_corr_^LAE^=7.4+/-3.6. These flux density ratios correspond, respectively, to relative LyC escape fractions of f_esc,rel_^LBG^=5%-8%, and f_esc,rel_^LAE^=18%-49% absolute LyC escape fractions of f_esc,rel_^LBG^=1%-2% and f_esc,rel_^LAE^=5%-15%, and a comoving LyC emissivity from star-forming galaxies of 8.8-15.0x10^24^ erg/s/Hz/Mpc^3^. In order to study the differential properties of galaxies with and without LyC detections, we analyze narrowband Ly{alpha} imaging and rest-frame near-infrared imaging, finding that while LAEs with LyC detections have lower Ly{alpha} equivalent widths on average, there is no substantial difference in the rest-frame near-infrared colors of LBGs or LAEs with and without LyC detections. These preliminary results are consistent with an orientation-dependent model where LyC emission escapes through cleared paths in a patchy interstellar medium.
