- ID:
- ivo://CDS.VizieR/J/AJ/156/49
- Title:
- The solar neighborhood. XLIII. New nearby stars
- Short Name:
- J/AJ/156/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a novel search of most of the southern sky for nearby red dwarfs having low proper motions, with specific emphasis on those with {mu}<0.18"/yr, the lower cutoff of Luyten's classic proper-motion catalog. We used a tightly constrained search of the SuperCOSMOS database and a suite of photometric distance relations for photographic BRI and 2MASS JHK_s_ magnitudes to estimate distances to more than 14 million red dwarf candidates. Here we discuss 29 stars in 26 systems estimated to be within 25 pc, all of which have {mu}<0.18"/yr, that we have investigated using milliarcsecond astrometry, VRI photometry, and low-resolution spectroscopy. In total, we present the first parallaxes of 20 star systems, 9 of which are within 25 pc. We have additionally identified 14 young M dwarfs, of which 3 are new members of the nearby young moving groups, and 72 new giants, including two new carbon stars. We also present the entire catalog of 1215 sources we have identified by this means.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/750/97
- Title:
- The yellow and red supergiants of M33
- Short Name:
- J/ApJ/750/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Yellow and red supergiants are evolved massive stars whose numbers and locations on the Hertzsprung-Russell (H-R) diagram can provide a stringent test for models of massive star evolution. Previous studies have found large discrepancies between the relative number of yellow supergiants (YSGs) observed as a function of mass and those predicted by evolutionary models, while a disagreement between the predicted and observed locations of red supergiants (RSGs) on the H-R diagram was only recently resolved. Here, we extend these studies by examining the YSG and RSG populations of M33. Unfortunately, identifying these stars is difficult as this portion of the color-magnitude diagram is heavily contaminated by foreground dwarfs. We identify the RSGs through a combination of radial velocities and a two-color surface gravity discriminant, and after re-characterizing the rotation curve of M33 with our newly selected RSGs, we identify the YSGs through a combination of radial velocities and the strength of the OI{lambda}7774 triplet. We examine ~1300 spectra in total and identify 121 YSGs (a sample that is unbiased in luminosity above log(L/L_{sun}_)~4.8) and 189 RSGs. After placing these objects on the H-R diagram, we find that the latest generation of Geneva evolutionary tracks shows excellent agreement with the observed locations of our RSGs and YSGs, the observed relative number of YSGs with mass, and the observed RSG upper mass limit.
- ID:
- ivo://CDS.VizieR/J/A+A/469/799
- Title:
- Torun catalog of post-AGB and related objects
- Short Name:
- J/A+A/469/799
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With the ongoing AKARI infrared sky survey, of much greater sensitivity than IRAS, a wealth of post-AGB objects may be discovered. It is thus time to organize our present knowledge of known post-AGB stars in the galaxy with a view to using it to search for new post-AGB objects among AKARI sources. We searched the literature available on the NASA Astrophysics Data System up to 1 October 2006, and defined criteria for classifying sources into three categories: very likely, possible and disqualified post-AGB objects. The category of very likely post-AGB objects is made up of several classes. We have created an evolutionary, on-line catalogue of Galactic post-AGB objects, to be referred to as the Torun catalogue of Galactic post-AGB and related objects. The present version of the catalogue contains 326 very likely, 107 possible and 64 disqualified objects. For the very likely post-AGB objects, the catalogue gives the available optical and infrared photometry, infrared spectroscopy and spectral types, and links to finding charts and bibliography.
- ID:
- ivo://CDS.VizieR/J/AJ/157/149
- Title:
- Transit parameters for planets around subgiants
- Short Name:
- J/AJ/157/149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of seven new planets and eight planet candidates around subgiant stars, as additions to the known sample of planets around "retired A stars". Among these are the possible first three-planet systems around subgiant stars, HD 163607 and HD 4917. Additionally, we present calculations of possible transit times, durations, depths, and probabilities for all known planets around subgiant (3<logg<4) stars, focused on possible transits during the TESS mission. While most have transit probabilities of 1%-2%, we find that there are three planets with transit probabilities >9%.
- ID:
- ivo://CDS.VizieR/J/ApJ/793/62
- Title:
- Triangulum-Andromeda stellar properties
- Short Name:
- J/ApJ/793/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As large-scale stellar surveys have become available over the past decade, the ability to detect and characterize substructures in the Galaxy has increased dramatically. These surveys have revealed the Triangulum-Andromeda (TriAnd) region to be rich with substructures in the distance range 20-30 kpc, and the relation of these features to each other, if any, remains unclear. An exploration using Two Micron All Sky Survey (2MASS) photometry reveals not only the faint sequence in M giants detected by Rocha-Pinto et al. (2004ApJ...615..732R) spanning the range 100{deg}<l<160{deg} and -50{deg}<b<-15{deg}, but, in addition, a second, brighter and more densely populated sequence. These sequences are likely associated with the distinct main sequences (MSs) discovered (and labeled TriAnd1 and TriAnd2) by Martin et al. (2007ApJ...668L.123M) in an optical survey in the direction of M31, where TriAnd2 is the optical counterpart of the fainter red giant branch (RGB)/asymptotic giant branch sequence of Rocha-Pinto et al. Here, the age, distance, and metallicity ranges for TriAnd1 and TriAnd2 are estimated by simultaneously fitting isochrones to the 2MASS RGB tracks and the optical MS/MS turn-off features. The two populations are clearly distinct in age and distance: the brighter sequence (TriAnd1) is younger (6-10 Gyr) and closer (distance of ~15-21 kpc), whereas the fainter sequence (TriAnd2) is older (10-12 Gyr) and at an estimated distance of ~24-32 kpc. A comparison with simulations demonstrates that the differences and similarities between TriAnd1 and TriAnd2 can simultaneously be explained if they represent debris originating from the disruption of the same dwarf galaxy, but torn off during two distinct pericentric passages.
- ID:
- ivo://CDS.VizieR/J/A+A/572/A108
- Title:
- 47 Tuc red giants chemical composition
- Short Name:
- J/A+A/572/A108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The study of chemical abundance patterns in globular clusters is of key importance to constrain the different candidates for intra-cluster pollution of light elements. We aim at deriving accurate abundances for a large range of elements in the globular cluster 47 Tucanae (NGC 104) to add new constraints to the pollution scenarios for this particular cluster, expanding the range of previously derived element abundances. Using tailored 1D LTE atmospheric models together with a combination of equivalent width measurements, LTE, and NLTE synthesis we derive stellar parameters and element abundances from high-resolution, high signal-to-noise spectra of 13 red giant stars near the tip of the RGB. We derive abundances of a total 27 elements (O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Mo, Ru, Ba, La, Ce, Pr, Nd, Eu, Dy). Departures from LTE were taken into account for Na, Al and Ba. We find a mean [Fe/H]=-0.78+/-0.07 and [alpha/Fe]=0.34+/-0.03 in good agreement with previous studies. The remaining elements show good agreement with the literature, but the inclusion of NLTE for Al has a significant impact on the behaviour of this key element. We confirm the presence of an Na-O anti-correlation in 47 Tucanae found by several other works. Our NLTE analysis of Al shifts the [Al/Fe] to lower values, indicating that this may be overestimated in earlier works. No evidence for an intrinsic variation is found in any of the remaining elements.
- ID:
- ivo://CDS.VizieR/J/A+A/621/A110
- Title:
- Two new giant planets around metal-poor stars
- Short Name:
- J/A+A/621/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Statistical studies of exoplanets have shown that giant planets are more commonly hosted by metal-rich dwarf stars than low-metallicity stars, while no such correlation is evident for lower mass planets. The search for giant planets around metal-poor stars and the estimate of their occurrence f_p_ is an important element in providing support to models of planet formation. We present results from the HARPS-N search for giant planets orbiting metal-poor (-1.0<=[Fe/H]<=-0.5dex) stars in the northern hemisphere, complementing a previous HARPS survey on southern stars in order to update the estimate of f_p_. High-precision HARPS-N observations of 42 metal-poor stars were used to search for planetary signals to be fitted using differential evolution Markov chain Monte Carlo single-Keplerian models. We then joined our detections to the results of the previous HARPS survey on 88 metal-poor stars to provide a preliminary estimate of the two-hemisphere f_p_. We report the detection of two new giant planets around HD 220197 and HD 233832. The first companion has Msini=0.20_-0.04_^+0.07^MJup and an orbital period of 1728_-80_^+162^days, and for the second companion, we find two solutions of equal statistical weight with periods of 2058_-40_^+47^ and 4047_-117_^+91^days and minimum masses of 1.78_-0.06_^+0.08^ and 2.72_-0.23_^+0.23^MJup, respectively. Joining our two detections with the three from the southern survey, we obtain a preliminary and conservative estimate of the global frequency of f_p_=3.84_-1.06_^+2.45^% for giant planets around metal-poor stars. The two new giant planets orbit dwarf stars at the metal-rich end of the HARPS-N metal-poor sample. This corroborates previous results that suggested that giant planet frequency is still a rising function of the host star [Fe/H]. We also note that all detections in the overall sample are giant long-period planets.
- ID:
- ivo://CDS.VizieR/J/PAZh/37/769
- Title:
- Tycho-2 red giant branch and carbon stars
- Short Name:
- J/PAZh/37/769
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on multicolor photometry from the 2MASS and Tycho-2 catalogues, we have produced a sample of 38368 branch red giants that has less than 1% of admixtures and is complete within 500 pc of the Sun. The sample includes 30671 K giants, 7544 M giants,49 C giants, and 104 suspected supergiants or S stars. The photometric distances have been calculated for K, M, and C stars with an accuracy of 40% together with reddening and extinction estimates. Tycho-2 proper motions and PCRV radial velocities are used to analyze the stellar kinematics. The majority of the selected K and M giants are disk stars with ages of more than 3Gyr. A small number of K and M giants are extremely young or, conversely, thick-disk ones. The spatial distribution and kinematics of the selected C stars force us to consider them as asymptotic branch giants with masses of more than 2 solar masses and ages of less than 2Gyr probably associated with the Gould Belt. The offset of the Sun above the Galactic equator has been found from the distribution of stars to be 13+/-2pc, which coincides with the previously obtained value for the clump red giants.
- ID:
- ivo://CDS.VizieR/J/A+A/423/189
- Title:
- UBV and RV of red giants in NGC 2477
- Short Name:
- J/A+A/423/189
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New, accurate radial velocities and photoelectric UBV photometry of 83 red-giant candidates in the field of the rich, intermediate-age open cluster NGC 2477 ([Fe/H]=-0.05, age ~1Gyr) are presented and discussed. From 49 constant-velocity members we find a mean cluster velocity of +7.32+/-0.13km/s and confirm the membership of 76 of the stars. Among the cluster members, we identify 26 definite and 1 probable spectroscopic binaries and determine orbits for 13 of these systems, with periods ranging from 40 to 4578 days. The binary frequency is thus rather high (27/76=36%). The observed internal radial velocity dispersion of the cluster, as determined from the single member stars, is 0.93km/s, corrected for the small average observational error of 0.22km/s. Fitting King-type models to the observed stellar density distribution and velocity dispersion, and assuming a distance of 1.25kpc, we find the core and tidal radii of NGC 2477 to be 1.8 and 8.1pc, respectively, and estimate that the mass of cluster stars down to V=17, corresponding to ~1M_{sun}_, is at least 5400 M_{sun}_. The substantial differential reddening of NGC 247 requires a more detailed study before definitive isochrone fits can be made.
- ID:
- ivo://CDS.VizieR/J/ApJ/663/296
- Title:
- UBV(RI)c phot. of omega Cen (NGC5139) subgiants
- Short Name:
- J/ApJ/663/296
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine spectroscopic and photometric data for subgiant stars of {omega} Cen to extract results that neither data set could have provided on its own. GIRAFFE@VLT spectra of 80 stars at R=6400 give metallicities for all of them and abundances of C, N, Ca, Ti, and Ba for a subset of them. The photometric data, which have unusually high accuracy, come from a ~10x10arcmin^2^ mosaic of HST ACS images centered on the cluster center and on multicolor images of a ~34x33arcmin^2^ field, taken with the WFI@ESO2.2m camera. Stars with [Fe/H]<-1.25 have a large magnitude spread on the flat part of the sub-giant branch (SGB). We interpret this as empirical evidence for an age spread, and from theoretical isochrones we derive a relative age for each star.
