- ID:
- ivo://CDS.VizieR/J/A+A/600/A4
- Title:
- M 2-9 ^12^CO and ^13^CO channel maps
- Short Name:
- J/A+A/600/A4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- M 2-9 is a young planetary nebula (PN) that shows the characteristics of its last ejections in unprecedented detail. These last ejections are thought to trigger the post-asymptotic giant branch evolution. To assemble an overall picture of how M 2-9 was shaped, we analyzed the characteristics of the different molecular gas components and their relation with the warmer parts of the nebula that are visible in the optical domain. ^12^CO and ^13^CO J=3-2 line emission maps were obtained with the Atacama Large Millimeter/submillimeter Array with high angular-resolution and sensitivity.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/454/2621
- Title:
- M4 Core Project with HST. Radial velocities
- Short Name:
- J/MNRAS/454/2621
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed study of the internal kinematics of the Galactic globular cluster M 4 (NGC 6121), by deriving the radial velocities from 7250 spectra for 2771 stars distributed from the upper part of the red giant branch down to the main sequence. We describe new approaches to determine the wavelength solution from day-time calibrations and to determine the radial velocity drifts that can occur between calibration and science observations when observing with the GIRAFFE spectrograph at Very Large Telescope. Two techniques to determine the radial velocity are compared, after a qualitative description of their advantages with respect to other commonly used algorithm, and a new approach to remove the sky contribution from the spectra obtained with fibre-fed spectrograph and further improve the radial velocity precision is presented. The average radial velocity of the cluster is <v>=71.08+/-0.08km/s with an average dispersion of {mu}_vc_=3.97km/s. Using the same data set and the same statistical approach of previous analyses, 20 additional binary candidates are found, for a total of 87 candidates. A new determination of the internal radial velocity dispersion as a function of cluster distance is presented, resulting in a dispersion of 4.5km/s within 2-arcmin from the centre of cluster and steadily decreasing outward. We statistically confirm the small amplitude of the cluster rotation, as suggested in the past by several authors. This new analysis represents a significant improvement with respect to previous results in literature and provides a fundamental observational input for the modelling of the cluster dynamics.
923. M31 CO(2-1) spectra
- ID:
- ivo://CDS.VizieR/J/A+A/549/A27
- Title:
- M31 CO(2-1) spectra
- Short Name:
- J/A+A/549/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With IRAM-30m/HERA, we have detected CO(2-1) gas complexes within 30arcsec (100pc) from the center of M31 that amount to a minimum total mass of 4.2x10^4^M_{sun}_ (one third of the positions are detected). Averaging the whole HERA field, we show that there is no additional undetected diffuse component. Moreover, the gas detection is associated with gas lying on the far side of the M31 center as no extinction is observed in the optical, but some emission is present on infrared Spitzer maps. The kinematics is complex. (1) The velocity pattern is mainly redshifted: the dynamical center of the gas differs from the black hole position and the maximum of optical emission, and only the redshifted side is seen in our data. (2) Several velocity components are detected in some lines of sight. Our interpretation is supported by the reanalysis of the effect of dust on a complete planetary nebula sample. Two dust components are detected with respective position angles of 37deg and -66deg. This is compatible with a scenario where the superposition of the (PA=37deg) disk is dominated by the 10kpc ring and the inner 0.7kpc ring detected in infrared data, whose position angle (-66deg) we measured for the first time. The large-scale disk, which dominates the HI data, is steeply inclined (i=77deg), warped and superposed on the line of sight on the less inclined inner ring. The detected CO emission might come from both components.
- ID:
- ivo://CDS.VizieR/J/MNRAS/324/33
- Title:
- MC WC/WO stars - Colliding winds
- Short Name:
- J/MNRAS/324/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Files br22rv.dat, br31rv.dat, br32rv.dat, ab8rv.dat, wr9rv.dat and wr30arv.dat contain spectroscopic radial velocity data of six Magellanic Cloud WC/WO class binary Wolf-Rayet stars. The data are derived from the C IV 5808{AA} emission line and the He II 5412{AA} absorption line. The data were obtained during one mission in 1984 at CTIO and two missions in 1993 at CASLEO.
- ID:
- ivo://CDS.VizieR/J/AJ/156/45
- Title:
- M-dwarf multiples in the SDSS-III/APOGEE
- Short Name:
- J/AJ/156/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Binary stars make up a significant portion of all stellar systems. Consequently, an understanding of the bulk properties of binary stars is necessary for a full picture of star formation. Binary surveys indicate that both multiplicity fraction and typical orbital separation increase as functions of primary mass. Correlations with higher-order architectural parameters such as mass ratio are less well constrained. We seek to identify and characterize double-lined spectroscopic binaries (SB2s) among the 1350 M-dwarf ancillary science targets with APOGEE spectra in the SDSS-III Data Release 13. We measure the degree of asymmetry in the APOGEE pipeline cross-correlation functions (CCFs) and use those metrics to identify a sample of 44 high-likelihood candidate SB2s. At least 11 of these SB2s are known, having been previously identified by Deshpande et al. (2013, J/AJ/146/156) and/or El-Badry et al. (2018MNRAS.476..528E). We are able to extract radial velocities (RVs) for the components of 36 of these systems from their CCFs. With these RVs, we measure mass ratios for 29 SB2s and five SB3s. We use Bayesian techniques to fit maximum-likelihood (but still preliminary) orbits for four SB2s with eight or more distinct APOGEE observations. The observed (but incomplete) mass-ratio distribution of this sample rises quickly toward unity. Two-sided Kolmogorov-Smirnov tests find probabilities of 18.3% and 18.7%, demonstrating that the mass-ratio distribution of our sample is consistent with those measured by Pourbaix et al. (2004, Cat. B/sb9) and Fernandez et al. (2017PASP..129h4201F), respectively.
- ID:
- ivo://CDS.VizieR/J/A+A/541/A9
- Title:
- M dwarfs activity and radial velocity
- Short Name:
- J/A+A/541/A9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Due to their low mass and luminosity, M dwarfs are ideal targets if one hopes to find low-mass planets similar to Earth by using the radial velocity (RV) method. However, stellar magnetic cycles could add noise or even mimic the RV signal of a long-period companion. Following our previous work that studied the correlation between activity cycles and long-term RV variations for K dwarfs we now expand that research to the lower-end of the main sequence. Our objective is to detect any correlations between long-term activity variations and the observed RV of a sample of M dwarfs. We used a sample of 27 M-dwarfs with a median observational timespan of 5.9 years. The cross-correlation function (CCF) with its parameters RV, bisector inverse slope (BIS), full-width-at-half- maximum (FWHM) and contrast have been computed from the HARPS spectrum. The activity index have been derived using the Na I D doublet. These parameters were compared with the activity level of the stars to search for correlations. We detected RV variations up to ~5m/s that we can attribute to activity cycle effects. However, only 36% of the stars with long-term activity variability appear to have their RV affected by magnetic cycles, on the typical timescale of ~6 years. Therefore, we suggest a careful analysis of activity data when searching for extrasolar planets using long-timespan RV data.
- ID:
- ivo://CDS.VizieR/J/ApJ/802/L10
- Title:
- M dwarf SpeX NIR spectroscopy
- Short Name:
- J/ApJ/802/L10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Despite the ubiquity of M dwarfs and their growing importance to studies of exoplanets, Galactic evolution, and stellar structure, methods for precisely measuring their fundamental stellar properties remain elusive. Existing techniques for measuring M dwarf luminosity, mass, radius, or composition are calibrated over a limited range of stellar parameters or require expensive observations. We find a strong correlation between the K_S_-band luminosity (M_K_), the observed strength of the I-band sodium doublet absorption feature, and [Fe/H] in M dwarfs without strong H{alpha} emission. We show that the strength of this feature, coupled with [Fe/H] and spectral type, can be used to derive M dwarf M_K_ and radius without requiring parallax. Additionally, we find promising evidence that the strengths of the I-band sodium doublet and the nearby I-band calcium triplet may jointly indicate {alpha}-element enrichment. The use of these I-band features requires only moderate-resolution near-infrared spectroscopy to provide valuable information about the potential habitability of exoplanets around M dwarfs, and surface gravity and distance for M dwarfs throughout the Galaxy. This technique has immediate applicability for both target selection and candidate planet-host system characterization for exoplanet missions such as TESS and K2.
- ID:
- ivo://CDS.VizieR/J/A+A/505/859
- Title:
- M dwarfs radial velocities
- Short Name:
- J/A+A/505/859
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present radial velocity (RV) measurements of our sample of 40 M dwarfs from our planet search programme with VLT+UVES begun in 2000. Although with our RV precision down to 2-2.5m/s and timebase line of up to 7 years we are capable of finding planets of few Earth masses in the close-in habitable zones of M dwarfs, there is no detection of a planetary companion. To demonstrate this we present mass detection limits allowing us to exclude Jupiter mass planets up to 1AU for most of our sample stars. We identified 6 M dwarfs that host a brown dwarf or low mass stellar companion. With the exception of these, all other sample stars show low RV variability with an rms <20m/s. Some high proper motion stars exhibit a linear RV trend consistent with their secular acceleration. Furthermore, we examine our data sets for a possible correlation between RVs and stellar activity as seen in variations of the Halpha line strength. For Barnard's star we found a significant anticorrelation, but most of the sample stars do not show such a correlation.
- ID:
- ivo://CDS.VizieR/J/A+A/602/A88
- Title:
- 5 M dwarfs radial velocity curves
- Short Name:
- J/A+A/602/A88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Low mass stars are currently the best targets for searches for rocky planets in the habitable zone of their host star. Over the last 13 years, precise radial velocities measured with the HARPS spectrograph have identified over a dozen super-Earths and Earth-mass planets (msini<=10M_{sun}_) around M dwarfs, with a well understood selection function. This well defined sample informs on their frequency of occurrence and on the distribution of their orbital parameters, and therefore already constrains our understanding of planetary formation. The subset of these low-mass planets that were found within the habitable zone of their host star also provide prized targets for future atmospheric biomarkers searches. We are working to extend this planetary sample to lower masses and longer periods through dense and long-term monitoring of the radial velocity of a small M dwarf sample. We obtained large numbers of HARPS spectra for the M dwarfs GJ 3138, GJ 3323, GJ 273, GJ 628 and GJ 3293, from which we derived radial velocities (RVs) and spectroscopic activity indicators. We searched them for variabilities, periodicities, Keplerian modulations and correlations, and attribute the radial-velocity variations to combinations of planetary companions and stellar activity. We detect 12 planets, of which 9 are new with masses ranging from 1.17 to 10.5M_{sun}_. Those planets have relatively short orbital periods (P<40d), except two of them with periods of 217.6 and 257.8 days. Among these systems, GJ 273 harbor two planets with masses close to the one of the Earth. With a distance of 3.8 parsec only, GJ 273 is the second nearest known planetary system - after Proxima Centauri - with a planet orbiting the circumstellar habitable zone.
- ID:
- ivo://CDS.VizieR/J/AN/328/889
- Title:
- Mean Radial Velocities of open clusters
- Short Name:
- J/AN/328/889
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the 2nd version of the Catalogue of Radial Velocities with Astrometric Data (CRVAD-2, Cat. <III/254>) for a new determination of mean RVs of 363 open clusters and stellar associations considering their defined members from proper motions and photometry in the All-Sky Compiled Catalogue of 2.5 Million Stars (ASCC-2.5, Cat. <I/280>). For 330 clusters and associations we compiled previously published RVs from the literature, critically reviewed and partly revised them. The resulting Catalogue of Radial Velocities of Open Clusters and Associations (CRVOCA) provides RVs for 516 open clusters and stellar associations in the Solar neighbourhood. Objects in the catalogue are sorted in the order of increasing right ascension J2000.
