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7601. VANDAM survey of Orion protostars. II.
ID:
ivo://CDS.VizieR/J/ApJ/890/130
Title:
VANDAM survey of Orion protostars. II.
Short Name:
J/ApJ/890/130
Date:
07 Mar 2022 13:26:15
Publisher:
CDS
Description:
We have conducted a survey of 328 protostars in the Orion molecular clouds with the Atacama Large Millimeter/submillimeter Array at 0.87mm at a resolution of ~0.1" (40au), including observations with the Very Large Array at 9mm toward 148 protostars at a resolution of ~0.08" (32au). This is the largest multiwavelength survey of protostars at this resolution by an order of magnitude. We use the dust continuum emission at 0.87 and 9mm to measure the dust disk radii and masses toward the Class 0, Class I, and flat-spectrum protostars, characterizing the evolution of these disk properties in the protostellar phase. The mean dust disk radii for the Class 0, Class I, and flat-spectrum protostars are 44.9_-3.4_^+5.8^, 37.0_-3.0_^+4.9^, and 28.5_-2.3_^+3.7^au, respectively, and the mean protostellar dust disk masses are 25.9_-4.0_^+7.7^, 14.9_-2.2_^+3.8^, 11.6_-1.9_^+3.5^M_{Earth}_, respectively. The decrease in dust disk masses is expected from disk evolution and accretion, but the decrease in disk radii may point to the initial conditions of star formation not leading to the systematic growth of disk radii or that radial drift is keeping the dust disk sizes small. At least 146 protostellar disks (35% of 379 detected 0.87mm continuum sources plus 42 nondetections) have disk radii greater than 50au in our sample. These properties are not found to vary significantly between different regions within Orion. The protostellar dust disk mass distributions are systematically larger than those of Class II disks by a factor of >4, providing evidence that the cores of giant planets may need to at least begin their formation during the protostellar phase.
7602. V348 And and V572 Per: heliocentric minima and RVs
ID:
ivo://CDS.VizieR/J/AJ/158/95
Title:
V348 And and V572 Per: heliocentric minima and RVs
Short Name:
J/AJ/158/95
Date:
21 Oct 2021
Publisher:
CDS
Description:
The eclipsing binaries are still important objects for our understanding of the universe. Especially these ones located within the more complex multiple systems can help us solving the problem of their origin and subsequent evolution of these higher order multiples. Photometry and spectroscopy spanning over more than 25 yr were used for the first complete analysis of the two bright triple systems, namely V348 And and V572 Per. The light curves in photometric filters were combined together with the radial velocities and analyzed simultaneously, yielding the precise physical parameters of the eclipsing components of these multiple systems. The system V348 And consists of two eclipsing components with its orbital period of about 27.7 days. The system is a very detached one, and both eclipses are rather narrow, lasting only about 0.016 of its period. The visual orbit of the wide pair has the period of about 87 yr. All three components of the system are probably of B8-9 spectral type, and the parallax of the system was slightly shifted to the value of 2.92 mas. On the other hand, the system V572 Per shows apsidal motion of its inner orbit, the orbital period being of about 1.2 days, while the apsidal motion of about 48 yr. The components are of A and F spectral types, while the motion with the third component around a common barycenter is only negligible. According to our modeling, this system is not a member of open cluster Alpha Persei.
7603. VANDELS High-Redshift Galaxy Evolution
ID:
ivo://CDS.VizieR/V/151
Title:
VANDELS High-Redshift Galaxy Evolution
Short Name:
V/151
Date:
21 Oct 2021
Publisher:
CDS
Description:
VANDELS is a new ESO spectroscopic Public Survey targeting the high-redshift Universe. Exploiting the red sensitivity of the refurbished VIMOS spectrograph, the survey is obtaining ultra-deep optical spectroscopy of around 2100 galaxies in the redshift interval 1.0<z<7.0, with 85% of its targets selected to be at z>=3. The fundamental aim of the survey is to provide the high signal-to-noise spectra necessary to measure key physical properties such as stellar population ages, metallicities and outflow velocities from detailed absorption-line studies. By targeting two extragalactic survey fields with superb multi-wavelength imaging data, VANDELS will produce a unique legacy dataset for exploring the physics underpinning high-redshift galaxy evolution.
7604. V and R CCD photometry of visual binaries
ID:
ivo://CDS.VizieR/J/A+A/416/811
Title:
V and R CCD photometry of visual binaries
Short Name:
J/A+A/416/811
Date:
21 Oct 2021
Publisher:
CDS
Description:
429 CCD measurements of relative positions and magnitude differences in V and R photometric bands for 165 visual double and multiple stars are given. CCD frames were taken at the 1.52m Spanish telescope of the Spanish-German Center of Astronomy at Calar Alto (Almeria, Spain). During the reduction process a "Tepui" function was used as the PSF function.
7605. V and Rc light curves of medium-bright PPNe
ID:
ivo://CDS.VizieR/J/AJ/159/21
Title:
V and Rc light curves of medium-bright PPNe
Short Name:
J/AJ/159/21
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present 10 years of new photometric monitoring of the light variability of five evolved stars with strong mid-infrared emission from surrounding dust. Three are known carbon-rich proto-planetary nebulae (PPNe) with F-G spectral types; the nature of the other two was previously unknown. For the three PPNe, we determine or refine the pulsation periods of IRAS04296+3429 (71 days), 06530-0213 (80 days), and 23304+6147 (84 days). A secondary period was found for each, with a period ratio P_2_/P_1_ of 0.9. The light variations are small, 0.1-0.2mag. These are similar to values found in other PPNe. The other two are found to be giant stars. IRAS09296+1159 pulsates with a period of only 47 days but reaches pulsational light variations of 0.5mag. Supplemental spectroscopy reveals the spectrum of a CH carbon star. IRAS08359-1644 is a G1III star that does not display pulsational variability; rather, it shows nonperiodic decreases of brightness of up to 0.5mag over this 10 year interval. These drops in brightness are reminiscent of the light curves of R Corona Borealis variables, but with much smaller decreases in brightness and are likely due to transient dust obscuration. Its spectral energy distribution is very similar to that of the unusual oxygen-rich giant star HDE233517, which possesses mid-infrared hydrocarbon emission features. These two non-PPNe turn out to be members of the rare group of giant stars with large mid-infrared excesses due to dust, objects which presumably have interesting evolutionary histories.
7606. V and R lightcurves of BL Lac object PKS 0537-441
ID:
ivo://CDS.VizieR/J/MNRAS/449/2750
Title:
V and R lightcurves of BL Lac object PKS 0537-441
Short Name:
J/MNRAS/449/2750
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the colour indices V-R of BL Lacertae object PKS 0537-441 on the basis of the photometric data monitored by the Rapid Eye Mounting (REM) telescope located at the ESO Cerro La Silla observatory (Chile). Nearly 700 quasi-simultaneous data groups were collected during the period from 2004 to 2010. Our colour analysis shows the existence of at least two variability mechanisms: one is the long-term chromatic mechanism in which the variation traces a 0.04+/-0.01 slope in the V-R versus V plot, the other is the chromatic mechanism implying the spectral changes during the flares and on intraday time-scales. A general bluer-when-brighter trend is confirmed in both ascent and descent states during the flares and in the 2010 February flare interval, while a much stronger bluer-when-brighter chromatism is observed in both faint and bright states on intraday time-scales. The discrete correlation function analysis reveals the existence of a time-lag of 13^+5.8^_-1.2_ d between colour indices and magnitudes during the period MJD 54404-54453, whereas no measurable time-lag during other periods is found. Our results suggest that geometric effects may be responsible for the long-term achromatic mechanism, while the intrinsic shock-in-jet mechanism may produce the chromatic variability during the flares and on intraday time-scales.
7607. V and R light curves of GSC 3822-1056
ID:
ivo://CDS.VizieR/J/A+A/403/637
Title:
V and R light curves of GSC 3822-1056
Short Name:
J/A+A/403/637
Date:
21 Oct 2021
Publisher:
CDS
Description:
Here we present the first Johnson-Cousins VR_C_ light curves of the over-contact binary star GSC 3822-1056. A period study and the light curve solution are also given. An extremely high rate of period increase +11.6sec/century was found. The origin of this period change can be: (i) partly covered light-time effect due to the orbital motion around the mass center of a possible third body; (ii) mass transfer between the components. The light curve was solved by the 1998 Wilson-Devinney Code. We examined the light curve with and without third light. Both solutions yielded a contact configuration with high temperature difference between the components. Despite the high degree of the contact (f=0.57), the temperature difference between the components {Delta}T=T_primary_-T_secondary_=1045K. The high mass-ratio of the system and its other unusual properties suggest that GSC 3822-1056 may be a recently formed contact binary.
7608. V466 And UBV(RI)c light curves
ID:
ivo://CDS.VizieR/J/other/CoSka/40.19
Title:
V466 And UBV(RI)c light curves
Short Name:
J/other/CoSka/40
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the UBV(RI)C photometry of a new dwarf nova V466 And, discovered during its superoutburst on Sept. 1.6, 2008 and classified as a WZ Sge-type object. In the first 11 days of the superoutburst, the early superhumps with the period of 0.056383d were found. In days 13-23 of the superoutburst, the ordinary superhumps with the period of 0.05713d were exposed. They were replaced by late superhumps with the period of 0.056d in days 24-33 of the superoutburst. After one month, the dwarf nova returned to its pre-outburst state. A list of known WZ Sge-type dwarf novae, including suspected ones, is presented. We determined a mean value of superhump period excess for WZ Sge-type objects as {epsilon}=0.019+/-0.003. The multicolour photometry of the field stars enables us to conclude that there is no appreciable interstellar extinction in the direction of V466 And.
7609. Variability classification of CoRoT targets
ID:
ivo://CDS.VizieR/J/A+A/550/A120
Title:
Variability classification of CoRoT targets
Short Name:
J/A+A/550/A120
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an improved method for automated stellar variability classification, using fundamental parameters derived from high resolution spectra, with the goal to improve the variability classification obtained using information derived from CoRoT light curves only. Although we focus on Giraffe spectra and CoRoT light curves in this work, the methods are much more widely applicable. In order to improve the variability classification obtained from the photometric time series, only rough estimates of the stellar physical parameters (Teff and logg) are needed because most variability types that overlap in the space of time series parameters, are well separated in the space of physical parameters (e.g. {gamma} Dor/SPB or {delta} Sct/{beta} Cep). In this work, several state-of-the-art machine learning techniques are combined to estimate these fundamental parameters from high resolution Giraffe spectra. Next, these parameters are used in a multi-stage Gaussian-Mixture classifier to perform an improved supervised variability classification of CoRoT light curves. The variability classifier can be used independently of the regression module that estimates the physical parameters, so that non-spectroscopic estimates derived e.g. from photometric colour indices can be used instead. Teff and logg are derived from Giraffe spectra, for 6832 CoRoT targets. The use of those parameters in addition to information extracted from the CoRoT light curves, significantly improves the results of our previous automated stellar variability classification. Several new pulsating stars are identified with high confidence levels, including hot pulsators such as SPB and {beta} Cep, and several {gamma} Dor-{delta} Sct hybrids. From our samples of new {gamma} Dor and {delta} Sct stars, we find strong indications that the instability domains for both types of pulsators are larger than previously thought.
7610. Variability in C-rich proto-PNe.
ID:
ivo://CDS.VizieR/J/ApJ/709/1042
Title:
Variability in C-rich proto-PNe.
Short Name:
J/ApJ/709/1042
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have carried out long-term (14 years) V and R photometric monitoring of 12 carbon-rich proto-planetary nebulae. The light and color curves display variability in all of them. The light curves are complex and suggest multiple periods, changing periods, and/or changing amplitudes, which are attributed to pulsation. A dominant period has been determined for each and found to be in the range of ~150 days for the coolest (G8) to 35-40 days for the warmest (F3). A clear, linear inverse relationship has been found in the sample between the pulsation period and the effective temperature and also an inverse relationship between the amplitude of light variation and the effective temperature. These are consistent with the expectation for a pulsating post-asymptotic giant branch (post-AGB) star evolving toward higher temperature at constant luminosity. The published spectral energy distributions and mid-infrared images show these objects to have cool (200K), detached dust shells and published models imply that intensive mass loss ended 400-2000 years ago.