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431. Photometry of Cepheids in Magellanic Clouds
ID:
ivo://CDS.VizieR/J/ApJS/117/135
Title:
Photometry of Cepheids in Magellanic Clouds
Short Name:
J/ApJS/117/135
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report BV(RI)C data for a select group of 14 Cepheids in the Large Magellanic Cloud and eight in the Small Magellanic Cloud that have preexisting radial velocity curves. The photometry was obtained as part of a program to determine distances to these Cepheids by means of the visual surface brightness technique and to improve significantly the optical BV(RI)C light curves of Magellanic Cloud Cepheids. The data were acquired on the 0.9 m telescope at Cerro Tololo Inter-American Observatory with the CFCCD instrument and with the 1 m photometric telescope at ESO using aperture photometry. The median number of measures per Cepheid is 46 in each band, and the uncertainty in the photometry is typically 0.01 mag. Using these data together with data from the literature, we determined improved periods for all variables. For most of the Cepheids, these revised periods lead to excellent, low-noise light curves, but for a few variables, the periods are obviously variable.
432. Photometry of Magellanic OB associations
ID:
ivo://CDS.VizieR/J/AJ/119/2214
Title:
Photometry of Magellanic OB associations
Short Name:
J/AJ/119/2214
Date:
21 Oct 2021
Publisher:
CDS
Description:
We combine new CCD UBV photometry and spectroscopy with those from the literature to investigate 19 Magellanic Cloud OB associations that contain Wolf-Rayet (W-R) and other types of evolved, massive stars. Our spectroscopy reveals a wealth of newly identified interesting objects, including early O-type supergiants, a high-mass, double-lined binary in the SMC, and, in the LMC, a newly confirmed luminous blue variable (LBV; R85), a newly discovered W-R star (Sk -69^deg^ 194), and a newly found luminous B[e] star (LH 85-10). We use these data to provide precise reddening determinations and construct physical H-R diagrams for the associations.
433. Photometry of NGC 1962-65-66-70
ID:
ivo://CDS.VizieR/J/A+A/301/396
Title:
Photometry of NGC 1962-65-66-70
Short Name:
J/A+A/301/396
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present CCD data in the Johnson passbands B and V of the young association NGC 1962-65-66-70 in the Large Magellanic Cloud.
434. Photometry of nova LMC 2012
ID:
ivo://CDS.VizieR/J/AJ/149/95
Title:
Photometry of nova LMC 2012
Short Name:
J/AJ/149/95
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of an intensive multiwavelength campaign on nova LMC 2012. This nova evolved very rapidly in all observed wavelengths. The time to fall two magnitudes in the V band was only 2days. In X-rays the super soft phase began 13+/-5days after discovery and ended around day 50 after discovery. During the super soft phase, the Swift/XRT and Chandra spectra were consistent with the underlying white dwarf (WD) being very hot, ~1MK, and luminous, ~10^38^erg/s. The UV, optical, and near-IR photometry showed a periodic variation after the initial and rapid fading had ended. Timing analysis revealed a consistent 19.24+/-0.03hr period in all UV, optical, and near-IR bands with amplitudes of ~0.3mag which we associate with the orbital period of the central binary. No periods were detected in the corresponding X-ray data sets. A moderately high inclination system, i=60+/-10{deg}, was inferred from the early optical emission lines. The HST/STIS UV spectra were highly unusual with only the N v (1240{AA}) line present and superposed on a blue continuum. The lack of emission lines and the observed UV and optical continua from four epochs can be fit with a low mass ejection event, ~10^-6^M_{sun}_, from a hot and massive WD near the Chandrasekhar limit. The WD, in turn, significantly illuminated its subgiant companion which provided the bulk of the observed UV/optical continuum emission at the later dates. The inferred extreme WD characteristics and low mass ejection event favor nova LMC 2012 being a recurrent nova of the U Sco subclass.
435. Photometry of the SMC cluster NGC 330
ID:
ivo://CDS.VizieR/J/A+AS/108/571
Title:
Photometry of the SMC cluster NGC 330
Short Name:
J/A+AS/108/571
Date:
21 Oct 2021
Publisher:
CDS
Description:
(no description available)
436. Planetary nebulae as standard candles. VI.
ID:
ivo://CDS.VizieR/J/ApJ/365/471
Title:
Planetary nebulae as standard candles. VI.
Short Name:
J/ApJ/365/471
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have measured the [O III] {lambda}5007 fluxes of the brightest planetaries in the LMC (102 objects) and SMC (31 objects) using narrow-band imaging at the CTIO 0.9m telescope. Our fluxes agree to -5% with photoelectric measurements available in the literature (31 objects); agreement is much worse for objects with only spectrophotometric observations. Using the fluxes for the complete sample of bright LMC planetaries, we derive a distance using the planetary nebula luminosity function (PNLF).
437. Polarisation of candidates Be stars
ID:
ivo://CDS.VizieR/J/ApJ/671/2040
Title:
Polarisation of candidates Be stars
Short Name:
J/ApJ/671/2040
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first detailed imaging polarization observations of six SMC and six LMC clusters, known to have large populations of B-type stars that exhibit excess H{alpha} emission from 2-CD photometric studies, to constrain the evolutionary status of these stars and hence better establish links between the onset of disk formation in classical Be stars and cluster age and/or metallicity. We parameterize and remove the interstellar polarization (ISP) associated with each line of sight, thereby isolating the presence of any intrinsic polarization. We use the wavelength dependence of this intrinsic polarization to discriminate pure gas disk systems, i.e., classical Be stars, from composite gas-plus-dust disk systems, i.e., Herbig Ae/Be or B[e] stars.
438. Post-AGB candidates in LMC and SMC SALT spectra
ID:
ivo://CDS.VizieR/J/A+A/641/A142
Title:
Post-AGB candidates in LMC and SMC SALT spectra
Short Name:
J/A+A/641/A142
Date:
21 Oct 2021
Publisher:
CDS
Description:
We selected a sample of post-AGB candidates in the Magellanic Clouds on the basis of their near- and mid-infrared colour characteristics. Fifteen of the most optically bright post-AGB candidates were observed with the South African Large Telescope in order to determine their stellar parameters and thus to validate or discriminate their nature as post-AGB objects in the Magellanic Clouds. The spectral types of absorption-line objects were estimated according to the MK classification, and effective temperatures were obtained by means of stellar atmosphere modelling. Emission-line objects were classified on the basis of the fluxes of the emission lines and the presence of the continuum. Out of 15 observed objects, only 4 appear to be genuine post-AGB stars (27%). In the SMC, 1 out of 4 is post-AGB, and in the LMC, 3 out 11 are post-AGB objects. Thus, we can conclude that the selected region in the colour-colour diagram, while selecting the genuine post-AGB objects, overlaps severely with other types of objects, in particular young stellar objects and planetary nebulae. Additional classification criteria are required to distinguish between post-AGB stars and other types of objects. In particular, photometry at far-IR wavelengths would greatly assist in distinguishing young stellar objects from evolved ones. On the other hand, we showed that the low-resolution optical spectra appear to be sufficient to determine whether the candidates are post-AGB objects.
439. Post-AGB/RGB and YSOs in SMC
ID:
ivo://CDS.VizieR/J/MNRAS/439/2211
Title:
Post-AGB/RGB and YSOs in SMC
Short Name:
J/MNRAS/439/2211
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have carried out a search for optically visible post-asymptotic giant branch (post-AGB) candidates in the Small Magellanic Cloud (SMC). First, we used mid-IR observations from the Spitzer Space Telescope to select optically visible candidates with excess mid-IR flux and then we obtained low-resolution optical spectra for 801 of the candidates. After removing poor-quality spectra and contaminants, such as M-stars, C-stars, planetary nebulae, quasi-stellar objects and background galaxies, we ended up with a final sample of 63 high-probability post-AGB/RGB candidates of A-F spectral type. From the spectral observations, we estimated the stellar parameters: effective temperature (T_eff_), surface gravity (logg) and metallicity ([Fe/H]). We also estimated the reddening and deduced the luminosity using the stellar parameters combined with photometry. For the post-AGB/RGB candidates, we found that the metallicity distribution peaks at [Fe/H]~-1.00dex. Based on a luminosity criterion, 42 of these 63 sources were classified as post-red giant branch (post-RGB) candidates and the remaining 21 as post-AGB candidates. From the spectral energy distributions, we were able to infer that 6 of the 63 post-AGB/RGB candidates have a surrounding circumstellar shell suggesting that they are single stars, while 27 of the post-AGB/RGB candidates have a surrounding disc, suggesting that they lie in binary systems. For the remaining 30 post-AGB/RGB candidates the nature of the circumstellar environment was unclear. Variability is displayed by 38 of the 63 post-AGB/RGB candidates with the most common variability types being the Population II Cepheids (including RV-Tauri stars) and semiregular variables. This study has also revealed a new RV Tauri star in the SMC, J005107.19-734133.3, which shows signs of s-process enrichment. From the numbers of post-AGB/RGB stars in the SMC, we were able to estimate evolutionary rates. We find that the number of post-AGB and post-RGB candidates that we have identified are in good agreement with the stellar evolution models with some mass-loss in the post-AGB phase and a small amount of re-accretion in the lower luminosity post-RGB phase. This study also resulted in a new sample of 40 young stellar objects (YSOs) of A-F spectral type. The 40 YSO candidates for which we could estimate stellar parameters are luminous and of high mass (~3-10M_{sun}_). They lie on the cool side of the usually adopted birthline in the HR-diagram. This line separates visually obscured protostars from optically visible pre-main-sequence stars, meaning that our YSO candidates have become optically visible in the region of the HR diagram usually reserved for obscured protostars. Additionally, we also identified a group of 63 objects whose spectra are dominated by emission lines and in some cases, a significant UV continuum. These objects are very likely to be either hot post-AGB/RGB candidates or luminous YSOs.
440. Probable Members of the SMC
ID:
ivo://CDS.VizieR/V/13
Title:
Probable Members of the SMC
Short Name:
V/13
Date:
21 Oct 2021
Publisher:
CDS
Description:
An objective prism survey was conducted to discover probable members of the Small Magellanic Cloud. Interference filters were used to restrict the wavelength range and, hence, decrease the background and crowding. The limiting absolute magnitude of the survey is about -4.5. The 1975 paper listed 506 stars that show high luminosity characteristics; 193 of them had been confirmed by other authors. The 1979 paper added 14 additional probable members and photometric observations of 11 stars from the earlier paper that confirmed their membership. For completeness, four new Wolf-Rayet stars detected by Azzopardi and Breysacher (1979) were included. The catalog contains a catalog number in order of right ascension with the suffixes "a" or "b" used for the newer stars interpolated in the original list. Also included are the 1975 position, the MK spectral classification, the V magnitude, the (B-V) and (U-B) color indices, the number of observations, the identification chart number, and remarks indicating previous identifications. A later catalogue of the Small Magellanic Could star members is also published by Azzopardi and Vigneau =1982A&AS...50..291A