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2761. Photometry and Proper Motions in M67
ID:
ivo://CDS.VizieR/V/52
Title:
Photometry and Proper Motions in M67
Short Name:
V/52
Date:
21 Oct 2021
Publisher:
CDS
Description:
Relative proper motions were determined for 1068 stars with limiting magnitude b=16.5 and located within an area 130'*130' centered at alpha=8h 47.7m,delta=+12 deg.00' and l=215.6deg.,b=+31.2deg.(1950.0). Five plate pairs taken with the Pulkovo normal astrograph with mean epoch difference of 62 years were used. The proper motions have a mean error of 0''.0020 per year and were measured relative to reference stars with 13.5<b<14.5. Photographic UBV magnitudes were determined using the photoelectric standards of Johnson, Sandage (1955ApJ...121..616J) and Eggen, Sandage (1964ApJ...140..130E). Three plates in each colour taken with the Schmidt telescope of the Radioastrophysical Observatory of the Latvian SSR were measured. In addition a plate taken with the Pulkovo 26inch telescope was used to determine v-magnitudes. The cluster members were selected on the basis of proper motion (vector point diagram) and photometric (V/B-V and U-B/B-V) criteria.
2762. Photometry and proper motions in Praesepe
ID:
ivo://CDS.VizieR/J/ApJ/784/57
Title:
Photometry and proper motions in Praesepe
Short Name:
J/ApJ/784/57
Date:
21 Oct 2021
Publisher:
CDS
Description:
Membership identification is the first step in determining the properties of a star cluster. Low-mass members in particular could be used to trace the dynamical history, such as mass segregation, stellar evaporation, or tidal stripping, of a star cluster in its Galactic environment. We identified member candidates of the intermediate-age Praesepe cluster (M44) with stellar masses ~0.11-2.4M_{sun}_, using Panoramic Survey Telescope And Rapid Response System and Two Micron All Sky Survey photometry, and PPMXL proper motions. Within a sky area of 3{deg} radius, 1040 candidates are identified, of which 96 are new inclusions. Using the same set of selection criteria on field stars, an estimated false positive rate of 16% was determined, suggesting that 872 of the candidates are true members. This most complete and reliable membership list allows us to favor the BT-Settl model over other stellar models. The cluster shows a distinct binary track above the main sequence, with a binary frequency of 20%-40%, and a high occurrence rate of similar mass pairs. The mass function is consistent with that of the disk population but shows a deficit of members below 0.3 solar masses. A clear mass segregation is evidenced, with the lowest-mass members in our sample being evaporated from this disintegrating cluster.
2763. Photometry and spectra of SN 2017dio
ID:
ivo://CDS.VizieR/J/ApJ/854/L14
Title:
Photometry and spectra of SN 2017dio
Short Name:
J/ApJ/854/L14
Date:
21 Oct 2021
Publisher:
CDS
Description:
SN 2017dio shows both spectral characteristics of a type-Ic supernova (SN) and signs of a hydrogen-rich circumstellar medium (CSM). Prominent, narrow emission lines of H and He are superposed on the continuum. Subsequent evolution revealed that the SN ejecta are interacting with the CSM. The initial SN Ic identification was confirmed by removing the CSM interaction component from the spectrum and comparing with known SNe Ic, and reversely, adding a CSM interaction component to the spectra of known SNe Ic and comparing them to SN 2017dio. Excellent agreement was obtained with both procedures, reinforcing the SN Ic classification. The light curve constrains the pre-interaction SN Ic peak absolute magnitude to be around Mg=-17.6mag. No evidence of significant extinction is found, ruling out a brighter luminosity required by a SN Ia classification. These pieces of evidence support the view that SN 2017dio is a SN Ic, and therefore the first firm case of a SN Ic with signatures of hydrogen-rich CSM in the early spectrum. The CSM is unlikely to have been shaped by steady-state stellar winds. The mass loss of the progenitor star must have been intense, dM/dt~0.02({epsilon}_Ha_/0.01)^-1^*(v_wind_/500km/s)* (v_shock_/10000km/s)^-3^M_{sun}_/yr, peaking at a few decades before the SN. Such a high mass loss rate might have been experienced by the progenitor through eruptions or binary stripping.
2764. Photometry and Spectroscopy for Luminous Stars
ID:
ivo://CDS.VizieR/V/125
Title:
Photometry and Spectroscopy for Luminous Stars
Short Name:
V/125
Date:
21 Oct 2021
Publisher:
CDS
Description:
of the paper: The birthrate of stars of masses >=10M_{sun}_ is estimated from a sample of just over 400 O3-B2 dwarfs within 1.5kpc of the Sun and the result extrapolated to estimate the Galactic supernova rate contributed by such stars. The solar-neighborhood Galactic-plane massive star birthrate is estimated at ~176stars/kpc^3^/Myr. On the basis of a model in which the Galactic stellar density distribution comprises a "disk+central hole" like that of the dust infrared emission (as proposed by Drimmel and Spergel), the Galactic supernova rate is estimated at probably not less than ~1 nor more than ~2 per century and the number of O3-B2 dwarfs within the solar circle at ~200000.
2765. Photometry and spectroscopy of AQ Ser
ID:
ivo://CDS.VizieR/J/AJ/147/36
Title:
Photometry and spectroscopy of AQ Ser
Short Name:
J/AJ/147/36
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report differential photometric observations and radial-velocity measurements of the detached, 1.69 day period, double-lined eclipsing binary AQ Ser. Accurate masses and radii for the components are determined to better than 1.8% and 1.1%, respectively, and are M_1_=1.417+/-0.021M_{sun}_, M_2_=1.346+/-0.024M_{sun}_, R_1_=2.451+/-0.027R_{sun}_, and R_2_=2.281+/-0.014R_{sun}_. The temperatures are 6340+/-100K (spectral type F6) and 6430+/-100K (F5), respectively. Both stars are considerably evolved, such that predictions from stellar evolution theory are particularly sensitive to the degree of extra mixing above the convective core (overshoot). The component masses are different enough to exclude a location in the H-R diagram past the point of central hydrogen exhaustion, which implies the need for extra mixing. Moreover, we find that current main-sequence models are unable to match the observed properties at a single age even when allowing the unknown metallicity, mixing length parameter, and convective overshooting parameter to vary freely and independently for the two components. The age of the more massive star appears systematically younger. AQ Ser and other similarly evolved eclipsing binaries showing the same discrepancy highlight an outstanding and largely overlooked problem with the description of overshooting in current stellar theory.
2766. Photometry and spectroscopy of CF Tauri
ID:
ivo://CDS.VizieR/J/AJ/144/167
Title:
Photometry and spectroscopy of CF Tauri
Short Name:
J/AJ/144/167
Date:
21 Oct 2021
Publisher:
CDS
Description:
CF Tau is now known to be an eclipsing triple star with relatively deep total and annular eclipses. New light and radial velocity curves as well as new times of minima were obtained and used for further modeling of the system. Very accurate (better than 0.9%) masses and radii of the eclipsing pair are determined from analysis of the two new light curves, the radial velocity curve, and the times of minimum light. The mass and luminosity of the distant third component is accurately determined as well. Theoretical models of the detached, evolved eclipsing pair match the observed absolute properties of the stars at an age of about 4.3Gyr and [Fe/H]=-0.14.
2767. Photometry and spectroscopy of EPIC 201702477
ID:
ivo://CDS.VizieR/J/AJ/153/15
Title:
Photometry and spectroscopy of EPIC 201702477
Short Name:
J/AJ/153/15
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the discovery of EPIC 201702477b, a transiting brown dwarf in a long period (40.73691+/-0.00037day) and eccentric (e=0.2281+/-0.0026) orbit. This system was initially reported as a planetary candidate based on two transit events seen in K2 Campaign 1 photometry and later validated as an exoplanet candidate. We confirm the transit and refine the ephemeris with two subsequent ground-based detections of the transit using the Las Cumbres Observatory Global Telescope 1m telescope network. We rule out any transit timing variations above the level of ~30s. Using high precision radial velocity measurements from HARPS and SOPHIE we identify the transiting companion as a brown dwarf with a mass, radius, and bulk density of 66.9+/-1.7M_J_, 0.757+/-0.065R_J_, and 191+/-51g/cm^3^ respectively. EPIC 201702477b is the smallest radius brown dwarf yet discovered, with a mass just below the H-burning limit. It has the highest density of any planet, substellar mass object, or main-sequence star discovered so far. We find evidence in the set of known transiting brown dwarfs for two populations of objects-high mass brown dwarfs and low mass brown dwarfs. The higher-mass population have radii in very close agreement to theoretical models, and show a lower-mass limit around 60M_J_. This may be the signature of mass-dependent ejection of systems during the formation process.
2768. Photometry and spectroscopy of LS V+44 17
ID:
ivo://CDS.VizieR/J/AJ/151/104
Title:
Photometry and spectroscopy of LS V+44 17
Short Name:
J/AJ/151/104
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the spectroscopic and photometric observations on the Be/X-ray binary RX J0440.9+4431 from 2001 to 2014. The short-term and long-term variability of the H{alpha} line profile indicates that one-armed global oscillations existed in the circumstellar disk. Several positive and negative correlations between the V-band brightness and the H{alpha} intensity were found from the long-term photometric and spectroscopic observations. We suggest that the monotonic increase of the V-band brightness and the H{alpha} brightness between our 2005 and 2007 observations might be the result of a continuous mass ejection from the central Be star, while the negative correlation in 2007-2010 should be caused by the cessation of mass loss from the Be star just before the decline in V-band brightness began (around our 2007 observations). With the extension of the ejection material, the largest circumstellar disk during the last two decades has been observed in our 2010 observations with an equivalent width of approximately -12.88{AA}, which corresponds to a circumstellar disk with a size of 12.9 times the radius of the central Be star. Three consecutive X-ray outbursts peaking around MJD 55293, 55444, and 55591 might be connected with the largest circumstellar disk around the Be star. We also use the orbital motion of the neutron star as a probe to constrain the structure of the circumstellar disk and estimate the eccentricity of the binary system to be >=0.4. After three years of the H{alpha} intensity decline after the X-ray outbursts, a new circumstellar disk was being formed around the Be star after our 2013 observations.
2769. Photometry and spectroscopy of NGC 6520
ID:
ivo://CDS.VizieR/J/AJ/147/7
Title:
Photometry and spectroscopy of NGC 6520
Short Name:
J/AJ/147/7
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use CCD and photoelectric photometry with Stromgren filters along with medium resolution spectra to investigate NGC 6520, an open cluster very nearly in the direction of the galactic center. We find an age of 60Myr, a distance of 2kpc, and an average reddening E(b-y)=0.295, which increases toward the south. The average heliocentric radial velocity of the B stars is -29km/s, while the velocity of the nearby Barnard 86 is about 0 (heliocentric; -11km/s compared to the LSR). This velocity difference amounts to about 1.8kpc since the cluster formed, implying that it is extremely doubtful NGC6520 is related to Barnard 86.
2770. Photometry and spectroscopy of RN LMC 1968
ID:
ivo://CDS.VizieR/J/MNRAS/491/655
Title:
Photometry and spectroscopy of RN LMC 1968
Short Name:
J/MNRAS/491/655
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a comprehensive review of all observations of the eclipsing recurrent Nova LMC 1968 in the Large Magellanic Cloud which was previously observed in eruption in 1968, 1990, 2002, 2010, and most recently in 2016. We derive a probable recurrence time of 6.2+/-1.2yr and provide the ephemerides of the eclipse. In the ultraviolet-optical-IR photometry the light curve shows high variability right from the first observation around 2 d after eruption. Therefore no colour changes can be substantiated. Outburst spectra from 2016 and 1990 are very similar and are dominated by H and He lines longward of 2000{AA}. Interstellar reddening is found to be E(B-V)=0.07+/-0.01. The super soft X-ray luminosity is lower than the Eddington luminosity and the X-ray spectra suggest the mass of the white dwarf (WD) is larger than 1.3M_{sun}_. Eclipses in the light curve suggest that the system is at high orbital inclination. On day 4 after the eruption a recombination wave was observed in FeII ultraviolet absorption lines. Narrow-line components are seen after day 6 and explained as being due to reionization of ejecta from a previous eruption. The UV spectrum varies with orbital phase, in particular a component of the HeII 1640{AA} emission line, which leads us to propose that early-on the inner WD Roche lobe might be filled with a bound opaque medium prior to the re-formation of an accretion disc. Both this medium and the ejecta can cause the delay in the appearance of the soft X-ray source.