- ID:
- ivo://CDS.VizieR/J/MNRAS/391/1210
- Title:
- Characteristics of energetic pulsars
- Short Name:
- J/MNRAS/391/1210
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we compare the characteristics of pulsars with a high spin-down energy loss rate (Edot) against those with a low Edot. We show that the differences in the total intensity pulse morphology between the two classes are in general rather subtle. A much more significant difference is the fractional polarization which is very high for high Edot pulsars and low for low Edot pulsars. The Edot at the transition is very similar to the death line predicted for curvature radiation. This suggests a possible link between high energy and radio emission in pulsars and could imply that gamma-ray efficiency is correlated with the degree of linear polarization in the radio band. As part of this study, we have discovered three previous unknown interpulse pulsars (and we detected one for the first time at 20cm). We also obtained rotation measures for 18 pulsars whose values had not previously been measured.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/159/281
- Title:
- Characteristics of 335 KOI stars
- Short Name:
- J/AJ/159/281
- Date:
- 09 Dec 2021
- Publisher:
- CDS
- Description:
- We propose several descriptive measures to characterize the arrangements of planetary masses, periods, and mutual inclinations within exoplanetary systems. These measures are based on complexity theory and capture the global, system-level trends of each architecture. Our approach considers all planets in a system simultaneously, facilitating both intrasystem and intersystem analysis. We find that based on these measures, Kepler's high-multiplicity (N>=3) systems can be explained if most systems belong to a single intrinsic population, with a subset of high-multiplicity systems (~20%) hosting additional, undetected planets intermediate in period between the known planets. We confirm prior findings that planets within a system tend to be roughly the same size and approximately coplanar. We find that forward modeling has not yet reproduced the high degree of spacing similarity (in log- period) actually seen in the Kepler data. Although our classification scheme was developed using compact Kepler multis as a test sample, our methods can be immediately applied to any other population of exoplanetary systems. We apply this classification scheme to 1- quantify the similarity between systems, 2- resolve observational biases from physical trends, 3- identify which systems to search for additional planets and where to look for these planets.
- ID:
- ivo://CDS.VizieR/J/MNRAS/505/L79
- Title:
- Characteristic time of stellar flares
- Short Name:
- J/MNRAS/505/L79
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Using the short-cadence data (1-min interval) of the Kepler space telescope, we conducted a statistical analysis for the characteristic time of stellar flares on Sun-like stars (SLS). Akin to solar flares, stellar flares show rise and decay light-curve profiles, which reflect the two distinct phases (rise phase and decay phase) of the flare process. We derived characteristic times of the two phases for the stellar flares of SLS, resulting in a median rise time of about 5.9min and a median decay time of 22.6min. It is found that both the rise time and the decay time of the stellar flares follow a lognormal distribution. The peak positions of the lognormal distributions for flare rise time and decay time are 3.5min and 14.8min, respectively. These time values for stellar flares are similar to the time-scale of solar flares, which supports the idea that stellar flares and solar flares have the same physical mechanism. The statistical results obtained in this work for SLS can be a benchmark of flare characteristic times when comparing with other types of stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/660/1556
- Title:
- Characterization of dusty debris disks
- Short Name:
- J/ApJ/660/1556
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dusty debris disks around main-sequence stars are signposts for the existence of planetesimals and exoplanets. From cross-correlating Hipparcos stars with the IRAS catalogs, we identify 146 stars within 120pc of Earth that show excess emission at 60um. This search took special precautions to avoid false positives. Our sample is reasonably well distributed from late B to early K-type stars, but it contains very few later type stars. Even though IRAS flew more than 20 years ago and many astronomers have cross-correlated its catalogs with stellar catalogs, we were still able to newly identify debris disks at as many as 33 main-sequence stars; of these, 32 are within 100pc of Earth. The power of an all-sky survey satellite like IRAS is evident when comparing our 33 new debris disks with the total of only 22 dusty debris disk stars first detected with the more sensitive, but pointed, satellite ISO. Our investigation focuses on the mass, dimensions, and evolution of dusty debris disks.
- ID:
- ivo://CDS.VizieR/J/AJ/119/2008
- Title:
- 10199 Chariklo stellar occultation: 1999-2005
- Short Name:
- J/AJ/119/2008
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Flagstaff Astrometric Scanning Transit Telescope was used to scan the sky in search of occultation candidates through which the Centaur 10199 Chariklo (formerly 1997 CU_26_) will pass in 1999-2005. Positions for 96,397 stars (magnitudes 7.5<V<17.3) were determined using differential reductions to the ACT catalog of star positions and proper motions, and accuracies of +/-30mas were achieved for well-exposed images. The ephemeris for 10199 Chariklo was improved by including the new positions presented in this paper and, second, by correcting older positions taken from the literature for systematic errors. During this time period, 10199 Chariklo passes within 2" of 117 of these stars, which are identified as occultation candidates in this paper. Among these, 28 candidates have magnitudes V<15.0, making them the best choices for observing programs using portable telescopes. Circumstances for each occultation are given. Because the angular radius of 10199 Chariklo is only about 15mas, the astrometry provided in this paper is only accurate enough for identifying possible occultation events and is not sufficient for predicting individual shadow paths across the surface of Earth, although representative cases are given. Last-minute astrometry with a large-aperture telescope will be needed to refine each prediction.
- ID:
- ivo://CDS.VizieR/J/A+A/431/773
- Title:
- CHARM2, an updated of CHARM catalog
- Short Name:
- J/A+A/431/773
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an update of the Catalog of High Angular Resolution Measurements (CHARM, Richichi & Percheron, 2002, Cat. <J/A+A/386/492>), which includes results available until July 2004. CHARM2 is a compilation of direct measurements by high angular resolution methods, as well as indirect estimates of stellar diameters. Its main goal is to provide a reference list of sources which can be used for calibration and verification observations with long-baseline optical and near-IR interferometers. Single and binary stars are included, as are complex objects from circumstellar shells to extragalactic sources. The present update provides an increase of almost a factor of two over the previous edition. Additionally, it includes several corrections and improvements, as well as a cross-check with the valuable public release observations of the ESO Very Large Telescope Interferometer (VLTI). A total of 8231 entries for 3238 unique sources are now present in CHARM2. This represents an increase of a factor of 3.4 and 2.0, respectively, over the contents of the previous version of CHARM.
- ID:
- ivo://CDS.VizieR/J/A+AS/114/109
- Title:
- Cha X-ray sources & optical identifications
- Short Name:
- J/A+AS/114/109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the observations of the ROSAT all-sky survey (RASS) in the direction of the Chamaeleon cloud complex, as well as the spectroscopic identifications of the detected X-ray sources. The main purpose of this identification program was the search for low mass pre-main sequence stars. Sixteen previously known PMS stars were detected with high confidence by ROSAT. Eight are classical T Tauri stars and eight are weak-line T Tauri stars. Seventy-seven new weak-line T Tauri stars were identified on the basis of the presence of strong Li {lambda}6707 absorption, spectral type later than F0 and chromospheric emission. We give coordinates and count rates of the X-ray sources, and present optical spectra and finding charts for the sources identified optically as new pre-main sequence stars. Optical UBV(RI)c and near-infrared JHKLM photometry for this sample of stars is also provided. In addition, 6 new dKe-dMe candidates are found among the RASS sources.
- ID:
- ivo://CDS.VizieR/J/A+A/599/A96
- Title:
- [C/H] Chemical abundances of 1110 stars
- Short Name:
- J/A+A/599/A96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Carbon, oxygen and nitrogen (CNO) are key elements in stellar formation and evolution, and their abundances should also have a significant impact on planetary formation and evolution. We aim to present a detailed spectroscopic analysis of 1110 solar-type stars, 143 of which are known to have planetary companions. We have determined the carbon abundances of these stars and investigate a possible connection between C and the presence of planetary companions. We used the HARPS spectrograph to obtain high-resolution optical spectra of our targets. Spectral synthesis of the CH band at 4300{AA} was performed with the spectral synthesis codes MOOG and FITTING. We have studied carbon in several reliable spectral windows and have obtained abundances and distributions that show that planet host stars are carbon rich when compared to single stars, a signature caused by the known metal-rich nature of stars with planets. We find no different behaviour when separating the stars by the mass of the planetary companion. We conclude that reliable carbon abundances can be derived for solar-type stars from the CH band at 4300{AA}. We confirm two different slope trends for [C/Fe] with [Fe/H] because the behaviour is opposite for stars above and below solar values. We observe a flat distribution of the [C/Fe] ratio for all planetary masses, a finding that apparently excludes any clear connection between the [C/Fe] abundance ratio and planetary mass.
- ID:
- ivo://CDS.VizieR/J/ApJ/802/93
- Title:
- Chemical abundance analysis of 5 stars in Sculptor
- Short Name:
- J/ApJ/802/93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a homogeneous chemical abundance analysis of five of the most metal-poor stars in the Sculptor dwarf spheroidal galaxy. We analyze new and archival high resolution spectroscopy from Magellan/MIKE and VLT/UVES and determine stellar parameters and abundances in a consistent way for each star. Two of the stars in our sample, at [Fe/H]=-3.5 and [Fe/H]=-3.8, are new discoveries from our Ca K survey of Sculptor, while the other three were known in the literature. We confirm that Scl 07-50 is the lowest metallicity star identified in an external galaxy, at [Fe/H]=-4.1. The two most metal-poor stars both have very unusual abundance patterns, with striking deficiencies of the {alpha} elements, while the other three stars resemble typical extremely metal-poor Milky Way halo stars. We show that the star-to-star scatter for several elements in Sculptor is larger than that for halo stars in the same metallicity range. This scatter and the uncommon abundance patterns of the lowest metallicity stars indicate that the oldest surviving Sculptor stars were enriched by a small number of earlier supernovae, perhaps weighted toward high-mass progenitors from the first generation of stars the galaxy formed.
- ID:
- ivo://CDS.VizieR/J/AJ/142/59
- Title:
- Chemical abundance in 10 open clusters
- Short Name:
- J/AJ/142/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed chemical abundance study of evolved stars in 10 open clusters based on Hydra multi-object echelle spectra obtained with the WIYN 3.5m telescope. From an analysis of both equivalent widths and spectrum synthesis, abundances have been determined for the elements Fe, Na, O, Mg, Si, Ca, Ti, Ni, Zr, and for two of the 10 clusters, Al and Cr. To our knowledge, this is the first detailed abundance analysis for clusters NGC 1245, NGC 2194, NGC 2355, and NGC 2425.