- ID:
- ivo://CDS.VizieR/J/A+A/606/A74
- Title:
- IRC +10216 13.3GHz-18.5GHz spectrum
- Short Name:
- J/A+A/606/A74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A spectral line survey of IRC +10216 between 13.3 and 18.5GHz was carried out using the Shanghai Tian Ma 65 m Radio Telescope (TMRT-65m) with a sensitivity of <7mK. Thirty-five spectral lines of 12 different molecules and radicals were detected in total. Except for SiS, the detected molecules are all carbon-chain molecules, including HC_3_N, HC_5_N, HC_7_N, HC_9_N, C_6_H, C_6_H^-^, C_8_H, SiC_2_, SiC_4_, c-C_3_H_2_, and l-C_5_H. The presence of rich carbon-bearing molecules is consistent with the identity of IRC +10216 as a carbon-rich asymptotic giant branch (AGB) star. The excitation temperatures and column densities of the observed species are derived by assuming a local thermodynamic equilibrium and homogeneous conditions.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/489/3492
- Title:
- IRC+10216 & omi Cet SCUBA-2 light curves
- Short Name:
- J/MNRAS/489/3492
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the sub-mm variability of two of the most well-studied AGB stars, IRC +10216 and omicron Ceti. The data are obtained at 450 and 850um as part of pointing calibration observations for the James Clerk Maxwell Telescope's SCUBA-2 instrument over a span of 7yr. The periods are derived using non-parametric methods, Gatspy Supersmoother and P4J, in order not to assume an underlying shape to the periodicity. These were compared to two Lomb-Scargle parametric methods. We find that for both sources and wavelengths the periods derived from all methods are consistent within {sigma}. The 850um phase folded light curves of IRC +10216 show a time lag of ~540d compared to its optical counterpart. We explore the origins of the sub-mm variability and the phase lag using radiative transfer models. Combining the modelling with findings in the literature, we find that the sub-mm emission and phase lag can be partially attributed to the dust formation or destruction cycle. A second, unknown mechanism must be invoked; we defer an investigation of the origin and nature of this mechanism to a future work.
- ID:
- ivo://CDS.VizieR/J/AJ/144/187
- Title:
- Iris photometry near southern Cepheids. V. AQ Pup
- Short Name:
- J/AJ/144/187
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A photometric UBV survey is presented for 610 stars in a region surrounding the Cepheid AQ Puppis and centered southwest of the variable, based upon photoelectric measures for 14 stars and calibrated iris photometry of photographic plates of the field for 596 stars. An analysis of reddening and distance for program stars indicates that the major dust complex in this direction is ~1.8kpc distant, producing differential extinction described by a ratio of total-to-selective extinction of R=A_V_/E_B-V_=3.10+/-0.20. Zero-age main-sequence fitting for the main group of B-type stars along the line of sight yields a distance of 3.21+/-0.19kpc (V_0_-M_V_=12.53+/-0.13s.e.). The 29.97 Cepheid AQ Pup, of field reddening E_B-V_=0.47+/-0.07 (E_B-V_(B0)=0.51+/-0.07), appears to be associated with B-type stars lying within 5' of it as well as with a sparse group of stars, designated Turner 14, centered south of it at J2000.0=07:58:37, -29:25:00, with a mean reddening of E_B-V_=0.81+/-0.01. AQ Pup has an inferred luminosity as a cluster member of <M_V_>=-5.40+/-0.25 and an evolutionary age of 3x10^7^yr. Its observed rate of period increase of +300.1+/-1.2s/yr is an order of magnitude larger than what is observed for Cepheids of comparable period in the third crossing of the instability strip, and may be indicative of a high rate of mass loss or a putative fifth crossing. Another sparse cluster, designated Turner 13, surrounds the newly recognized 2.59 Cepheid V620 Pup, of space reddening E_B-V_=0.64+/-0.02 (E_B-V_(B0)=0.68+/-0.02), distance 2.88+/-0.11kpc (V_0_-M_V_=12.30+/-0.08s.e.), evolutionary age 10^8^yr, and an inferred luminosity as a likely cluster member of <M_V_>=-2.74+/-0.11. V620 Pup is tentatively identified as a first crosser, pending additional observations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/386/313
- Title:
- IR observations of Mira variables
- Short Name:
- J/MNRAS/386/313
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Published data for large-amplitude asymptotic giant branch variables in the Large Magellanic Cloud (LMC) are re-analysed to establish the constants for an infrared (K) period-luminosity relation of the form MK={rho}[logP-2.38]+{delta}. A slope of {rho}=-3.51+/-0.20 and a zero-point of {delta}=-7.15+/-0.06 are found for oxygen-rich Miras (if a distance modulus of 18.39+/-0.05 is used for the LMC). Assuming this slope is applicable to Galactic Miras we discuss the zero-point for these stars using the revised Hipparcos parallaxes together with published very long baseline interferometry (VLBI) parallaxes for OH masers and Miras in globular clusters. These result in a mean zero-point of {delta}=-7.25+/-0.07 for O-rich Galactic Miras. The zero-point for Miras in the Galactic bulge is not significantly different from this value.
- ID:
- ivo://CDS.VizieR/J/A+A/566/A37
- Title:
- Iron abundances for 42 Galactic Cepheids
- Short Name:
- J/A+A/566/A37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present homogeneous and accurate iron abundances for 42 Galactic Cepheids based on high resolution (R~38000) high signal-to-noise ratio (S/N>=100) optical spectra collected with UVES at VLT (128 spectra). The above abundances were complemented with high-quality iron abundances provided either by our group (86) or available in the literature. We were careful to derive a common metallicity scale and ended up with a sample of 450 Cepheids. We also estimated accurate individual distances for the entire sample by using homogeneous near-infrared photometry and the reddening free period-Wesenheit relations. The new metallicity gradient is linear over a broad range of Galactocentric distances (R_G_~5-19kpc) and agrees quite well with similar estimates available in the literature (-0.060+/-0.002dex/kpc). We also uncover evidence that suggests that the residuals of the metallicity gradient are tightly correlated with candidate Cepheid groups (CGs). The candidate CGs have been identified as spatial overdensities of Cepheids located across the thin disk. They account for a significant fraction of the residual fluctuations, and also for the large intrinsic dispersion of the metallicity gradient. We performed a detailed comparison with metallicity gradients based on different tracers: OB stars and open clusters. We found very similar metallicity gradients for ages younger than 3Gyr, while for older ages we found a shallower slope and an increase in the intrinsic spread. The above findings rely on homogeneous age, metallicity, and distance scales. Finally, by using a large sample of Galactic and Magellanic Cepheids for which accurate iron abundances are available, we found that the dependence of the luminosity amplitude on metallicity is vanishing.
- ID:
- ivo://CDS.VizieR/J/AJ/158/105
- Title:
- IR photometry of field RR Lyrae variable stars
- Short Name:
- J/AJ/158/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multi-epoch infrared photometry in the K_s_-band for 74 bright RR Lyrae variable stars tied directly to the Two-Micron All-Sky Survey (2MASS) photometric system. We systematize additional K-band photometry from the literature to the 2MASS system and combine it to obtain photometry for 146 RR Lyrae stars on a consistent, modern system. A set of outlier stars in the literature photometry is identified and discussed. Reddening estimates for each star are gathered from the literature and combined to provide an estimate of the interstellar absorption affecting each star, and we find excellent agreement with another source in the literature. We utilize trigonometric parallaxes from the Second Data Release of the European Space Agency's Gaia astrometric satellite to determine the absolute magnitude, M_Ks_ for each of these stars, and analyze them using the astrometry-based luminosity prescription to obtain a parallax-based calibration of M_K_ (RR). Our period-luminosity-metallicity relationship is M_Ks_=(-2.8+/-0.2)(logP+0.27)+(0.12+/-0.02) ([Fe/H]+1.3)-(0.41+/-0.03) mag. A Gaia global zero-point error of {pi}_zp_=-0.042+/-0.013 mas is determined for this sample of RR Lyrae stars.
- ID:
- ivo://CDS.VizieR/J/AJ/99/784
- Title:
- IR photometry of LMC long-period variables
- Short Name:
- J/AJ/99/784
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Infrared JHK photometry and visual spectra have been obtained for a large sample of long-period variables (LPVs) in the Large Magellanic Cloud (LMC). Various aspects of the asymptotic giant branch (AGB) evolution of LPVs are discussed using these data. The birth/death rate of LPVs of different ages in the LMC is compared with the birth rates of appropriate samples of planetary nebulae clump stars, Cepheids, and OH/IR stars. It appears that there are much fewer large-amplitude LPVs per unit galactic stellar mass in the LMC than in the Galaxy. We suggest that this may be due to the fact that the evolved intermediate-age AGB stars in the LMC often turn into carbon stars, which tend to have smaller pulsation amplitudes than M stars. There is also a major discrepancy between the number of LPVs in the LMC (and in the Galaxy) and the number predicted by the theories of AGB evolution, pulsation, and mass loss. A distance modulus to the LMC of 18.66+0.05 is derived by comparing the LMC LPVs with P~200days with the 47 Tucanae Mira variables in the (K, logP) plane. The (K, logP) relation is also used to examine the tilt of the LMC populations of old and intermediate-age stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/442/273
- Title:
- IR photometry of NGC 1893 variables
- Short Name:
- J/MNRAS/442/273
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present time series photometry of 104 variable stars in the cluster region NGC 1893. The association of the present variable candidates to the cluster NGC 1893 has been determined by using (U-B)/(B-V) and (J-H)/(H-K) two colour diagrams, and V/(V-I) colour-magnitude diagram. 45 stars are found to be main-sequence variables and these could be B-type variable stars associated with the cluster. We classified these objects as {beta} Cep, slowly pulsating B stars and new class variables as discussed by Mowlavi et al. (2013, Cat. J/A+A/554/A108). These variable candidates show ~0.005 to ~0.02mag brightness variations with periods of <1.0d. 17 new class variables are located in the H-R diagram between the slowly pulsating B stars and {delta} Scuti variables. Pulsation could be one of the causes for periodic brightness variations in these stars. The X-ray emission of present main-sequence variables associated with the cluster lies in the saturated region of X-ray luminosity versus period diagram and follows the general trend by Pizzolato et al. (2003, Cat. J/A+A/397/147).
- ID:
- ivo://CDS.VizieR/J/MNRAS/481/4206
- Title:
- IRSF survey of variable stars in the SMC
- Short Name:
- J/MNRAS/481/4206
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A very long-term near-infrared variable star survey towards the Large and Small Magellanic Clouds (LMC and SMC) was carried out using the 1.4m InfraRed Survey Facility at the South African Astronomical Observatory. This project was initiated in 2000 December in the LMC, and in 2001 July in the SMC. Since then an area of 3deg^2^ along the bar in the LMC and an area of 1deg^2^ in the central part of the SMC have been repeatedly observed. This survey is ongoing, but results obtained with data taken until 2017 December are reported in this paper. Over more than 15yr we have observed the two survey areas more than one hundred times. This is the first survey that provides near-infrared time-series data with such a long time baseline and on such a large scale. This paper describes the observations in the SMC and publishes a point source photometric catalogue, a variable source catalogue, and time-series data.
- ID:
- ivo://CDS.VizieR/J/AJ/151/146
- Title:
- IRS spectra with features of crystalline silicates
- Short Name:
- J/AJ/151/146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The crystalline silicate features are mainly reflected in infrared bands. The Spitzer Infrared Spectrograph (IRS) collected numerous spectra of various objects and provided a big database to investigate crystalline silicates in a wide range of astronomical environments. We apply the manifold ranking algorithm to perform a systematic search for the spectra with crystalline silicate features in the Spitzer IRS Enhanced Products available. In total, 868 spectra of 790 sources are found to show the features of crystalline silicates. These objects are cross-matched with the SIMBAD database as well as with the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST)/DR2 (Luo et al. 2016, Cat. V/149). The average spectrum of young stellar objects shows a variety of features dominated either by forsterite or enstatite or neither, while the average spectrum of evolved objects consistently present dominant features of forsterite in AGB, OH/IR, post-AGB, and planetary nebulae. They are identified optically as early-type stars, evolved stars, galaxies and so on. In addition, the strength of spectral features in typical silicate complexes is calculated. The results are available through CDS for the astronomical community to further study crystalline silicates.
