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341. Differential photometry of GJ1214
ID:
ivo://CDS.VizieR/J/A+A/614/A35
Title:
Differential photometry of GJ1214
Short Name:
J/A+A/614/A35
Date:
21 Oct 2021
Publisher:
CDS
Description:
To investigate the star spots of the M dwarf GJ 1214, we conducted a multi-color photometric monitoring from 2012 to 2016. We measured the rotation period of the host star, measured an increase in variability amplitude, determined the permanent spot filling factor, the spot temperature contrast and persistent longitudes. We determined the effect of the star spots on the planetary transmission spectrum.
342. Differential photometry of HD 8801
ID:
ivo://CDS.VizieR/J/AJ/129/2026
Title:
Differential photometry of HD 8801
Short Name:
J/AJ/129/2026
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have discovered the first example of a star pulsating intrinsically with both {gamma} Doradus and {delta} Scuti frequencies. HD 8801 is an Am metallic-line star that appears to be single. Since the vast majority of Am stars are members of binary systems with periods less than 1000 days and also do not pulsate, HD 8801 possesses a very unusual, if not unique, combination of physical properties. Our photometry, acquired with an automatic telescope at Fairborn Observatory, resolves six independent pulsation periods between 0.048 and 0.404 days. The two longest periods lie within the range of {gamma} Dor variables, while the four shorter periods are within the range of {delta} Sct stars.
343. Differential photometry of WX Cet
ID:
ivo://CDS.VizieR/J/A+A/463/1053
Title:
Differential photometry of WX Cet
Short Name:
J/A+A/463/1053
Date:
21 Oct 2021
Publisher:
CDS
Description:
WX Cet is a dwarf nova with rare outbursts of large amplitude. We compile the available data of WX Cet, compare the results with other SU UMa stars, and discuss our findings in the context of current theories of superhumps and superoutbursts to progress with our understanding of SU UMa stars.
344. Differential uvby photometry of HD 239276
ID:
ivo://CDS.VizieR/J/A+A/456/261
Title:
Differential uvby photometry of HD 239276
Short Name:
J/A+A/456/261
Date:
21 Oct 2021
Publisher:
CDS
Description:
The variability of HD 239276 was suspected photometrically nearly twenty years ago, but was confirmed with new observations obtained in 2001 during a two-site photometric campaign carried out from Spain, in uvby{beta} Stroemgren-Crawford photometry, and China, using the Johnson V filter. Two low-dispersion spectra were also collected. The results establish this star as a new multiperiodic gamma Dor-type pulsator with deficiency in metallicity.
345. Differential uvby photometry of HD 218427
ID:
ivo://CDS.VizieR/J/A+A/450/715
Title:
Differential uvby photometry of HD 218427
Short Name:
J/A+A/450/715
Date:
21 Oct 2021
Publisher:
CDS
Description:
Table 1 contents 845 simultaneous measurements collected in each of the four uvby colours of the Stromgren photometric system for the Gamma Doradus variable HD 218427. The data are magnitude differences (Du, Dv, Db, Dy, D(b-y), Dm1, Dc1) of the variable star minus comparison star in the standard system versus Heliocentric Julian Date. The comparison star is HD 219874. The origin in time is the Julian Day 2452839. The observations were carried out by the authors through the year 2003 using the 0.90m telescope at Sierra Nevada Observatory, Spain (Julian Days:0 to 69 in the table) and the 1.50m telescope at San Pedro Martir Observatory, Mexico (Julian Days: 122 to 128). Both telescopes are equipped with identical six-channel uvby-Hbeta spectrograph photometers for simultaneous measurements in uvby or in the narrow and wide H{beta} channels, respectively. Please note that a technical problem arose with the "u" filter in the 1.50m telescope, which made the "u" data collected with that telescope useless and they are named as 99.
346. Differential V photometry of V350 Peg
ID:
ivo://CDS.VizieR/II/242
Title:
Differential V photometry of V350 Peg
Short Name:
II/242
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present all the CCD photometric observations of the {delta} Scuti star V350 Peg performed by us until now. The data have been acquired between July 1997 and October 2002. A large part of it has been analysed and presented previously (Vidal, 2002A&A...394..585V). The new data of 2002 confirm the former conclusion that two frequencies of very similar amplitudes are excited in this star. The entire data set consists of 16191 measurements collected during 48 nights, and may be very helpful to investigate the detailed behaviour of this basically double-mode {delta} Scuti variable if future campaigns are held at a later stage.
347. DIRECT lightcurves of 21 luminous YSGs in M33
ID:
ivo://CDS.VizieR/J/A+A/601/A76
Title:
DIRECT lightcurves of 21 luminous YSGs in M33
Short Name:
J/A+A/601/A76
Date:
21 Oct 2021
Publisher:
CDS
Description:
The evolution of massive stars surviving the red supergiant (RSG) stage remains unexplored due to the rarity of such objects. The yellow hypergiants (YHGs) appear to be the warm counterparts of post-RSG classes located near the Humphreys-Davidson upper luminosity limit, which are characterized by atmospheric instability and high mass-loss rates. We aim to increase the number of YHGs in M33 and thus to contribute to a better understanding of the pre-supernova evolution of massive stars. Optical spectroscopy of five dust-enshrouded YSGs selected from mid-IR criteria was obtained with the goal of detecting evidence of extensive atmospheres. We also analyzed BVIc photometry for 21 of the most luminous YSGs in M33 to identify changes in the spectral type. To explore the properties of circumstellar dust, we performed SED-fitting of multi-band photometry of the 21 YSGs. We find three luminous YSGs in our sample to be YHG candidates, as they are surrounded by hot dust and are enshrouded within extended, cold dusty envelopes. Our spectroscopy of star 2 shows emission of more than one H{alpha} component, as well as emission of CaII, implying an extended atmospheric structure. In addition, the long-term monitoring of the star reveals a dimming in the visual light curve of amplitude larger than 0.5mag that caused an apparent drop in the temperature that exceeded 500K. We suggest the observed variability to be analogous to that of the Galactic YHG {rho} Cas. Five less luminous YSGs are suggested as post-RSG candidates showing evidence of hot or/and cool dust emission. We demonstrate that mid-IR photometry, combined with optical spectroscopy and time-series photometry, provide a robust method for identifying candidate YHGs. Future discovery of YHGs in Local Group galaxies is critical for the study of the late evolution of intermediate-mass massive stars.
348. DIRECT variables in M33B field
ID:
ivo://CDS.VizieR/J/AJ/122/2477
Title:
DIRECT variables in M33B field
Short Name:
J/AJ/122/2477
Date:
21 Oct 2021
Publisher:
CDS
Description:
DIRECT is a project to obtain directly the distances to two Local Group galaxies, M31 and M33, which occupy a crucial position near the bottom of the cosmological distance ladder. As the first step of the DIRECT project we have searched for detached eclipsing binaries (DEBs) and new Cepheids in the M31 and M33 galaxies with 1m class telescopes. In this eighth paper we present a catalog of variable stars discovered in the data from the follow-up observations of DEB system D33J013337.0+303032.8 in field M33B [(RA,DE)=(23.48{deg}, 30.57{deg}), J2000.0], collected with the Kitt Peak National Observatory 2.1m telescope. In our search covering an area of 108arcmin^2^ we have found 895 variable stars: 96 eclipsing binaries, 349 Cepheids, and 450 other periodic, possibly long-period or nonperiodic variables. Of these variables 612 are newly discovered. Their light curves were extracted using the ISIS image subtraction package. For 77% of the variables we present light curves in standard V and B magnitudes, with the remaining 23% expressed in units of differential flux. We have discovered a population of first-overtone Cepheid candidates, and for six of them we present strong arguments in favor of this interpretation. The catalog of variables, as well as their photometry (about 9.2x10^4^ BV measurements) and finding charts, is available electronically via anonymous ftp and the World Wide Web. The complete set of the CCD frames is available upon request.
349. Distances of cataclysmic variables
ID:
ivo://CDS.VizieR/J/AJ/136/2107
Title:
Distances of cataclysmic variables
Short Name:
J/AJ/136/2107
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report parallax and distance estimates for 12 more cataclysmic binaries and related objects observed with the 2.4m Hiltner telescope at MDM Observatory. The final parallax accuracy is typically ~1mas.
350. Distances of Cataclysmic variables
ID:
ivo://CDS.VizieR/J/AJ/126/3017
Title:
Distances of Cataclysmic variables
Short Name:
J/AJ/126/3017
Date:
21 Oct 2021
Publisher:
CDS
Description:
The 2.4m Hiltner Telescope at MDM Observatory was used in an attempt to measure trigonometric parallaxes for 14 cataclysmic variable stars. Techniques are described in detail. In the best cases the parallax uncertainties are below 1mas, and significant parallaxes are found for most of the program stars. A Bayesian method that combines the parallaxes together with proper motions and absolute magnitude constraints is developed and used to derive distance estimates and confidence intervals. The most precise distance derived here is for WZ Sge, for which is found to be 43.3^+1.6^_-1.5_pc. Six Luyten Half-Second stars with previous precise parallax measurements were remeasured to test the techniques, and good agreement was found.