Distance Scale For Planetary Nebulae Research Articles

A New Statistical Distance Scale for Planetary Nebulae, Based on Gaia EDR3

The present work aims to build a new statistical distance scale for planetary nebulae (PNe) based on a rigorous calibration sample. The distances of the calibration sample are derived from the trigonometric parallax method using the recent measurements of Gaia Early Data Release 3 (Gaia EDR3). The new distance scale is created by applying the well-known linear relationship between the radio surface brightness temperature and the nebular radius. The calibration sample is made up of 96 PNe of accurately computed distances with uncertainties less than 20%. Earlier ground- and space-based trigonometric parallaxes of PNe display inconsistency with those of Gaia, particularly the Hipparcos results. In addition, these measurements have appreciably lower precision than those of Gaia. When compared to the trigonometric technique, the expansion and kinematic methods exhibited more consistency than the spectroscopic, extinction, gravity, and photoionization methods. Furthermore, contrary to earlier results in the literature, the extinction and gravity methods, on average, underestimate and slightly overestimate the PN distances respectively. As a byproduct of extracting the Gaia parallaxes, we detect the radial velocity and variability for 14 and 3 PN central stars (CSs), respectively. To our knowledge, the variability of Hen 2-447 CS has been determined for the first time.

A new statistical distance scale for planetary nebulae

In the first part of the present article we discuss the consistency among different individual distance methods of Galactic planetary nebulae, while in the second part we develop a new statistical distance scale based on a calibrating sample of well determined distances. A set composed of 315 planetary nebulae with individual distances are extracted from the literature. Inspecting the data set indicates that the accuracy of distances is varying among different individual methods and also among different sources where the same individual method was applied. Therefore, we derive a reliable weighted mean distance for each object by considering the influence of the distance error and the weight of each individual method. The results reveal that the discussed individual methods are consistent with each other, except the gravity method that produces higher distances compared to other individual methods. From the initial data set, we construct a standard calibrating sample consists of 82 objects. This sample is restricted only to the objects with distances determined from at least two different individual methods, except few objects with trusted distances determined from the trigonometric, spectroscopic, and cluster membership methods. In addition to the well determined distances for this sample, it shows a lot of advantages over that used in the prior distance scales. This sample is used to recalibrate the mass-radius and radio surface brightness temperature-radius relationships. An average error of ∼30 % is estimated for the new distance scale. The newly distance scale is compared with the most widely used statistical scales in literature, where the results show that it is roughly similar to the majority of them within ∼±20 % difference. Furthermore, the new scale yields a weighted mean distance to the Galactic center of 7.6±1.35 kpc, which in good agreement with the very recent measure of Malkin 2013.

A revised distance scale of planetary nebulae

Context. The advent of large-scale, high-sensitivity surveys of the Galaxy (2MASS, WISE, Spitzer, etc.) has allowed detection of a large number of planetary nebulae (PNe), some of them at large distances. Aims. I propose a new distance scale of planetary nebulae, based on two main quantities: the flux density (or magnitude) at 8 μm and the nebular apparent size. Methods. I used these quantities to calculate the specific intensity of the radiation I8 μm, which decreases as the nebula evolves. The PNe situated in the Large Magellanic Cloud (LMC) with 8 μm photometry obtained by Spitzer and diameter obtained from HST observations were used as calibrators. Results. After calibration, I recalculated distances of PNe in the LMC, and they show a one-sigma spread of 10 kpc (20%). Eventually, I applied the method to a sample of 47 Galactic PNe observed during the Spitzer survey. These results showed agreement within 0.2 dex with the distances determined with another method of calibrating with PNe in the LMC. Conclusions. The main advantage of the present distance scale is that it is nearly “extinction free”, which makes it especially suited to PNe severely affected by interstellar extinction, such as the Galactic disc and bulge. On the other hand, the method requires an unbiased determination of the nebular size, which might be quite uncertain for PNe with extended faint features, such as haloes and ansae.

New Statistical Distance Scale of Planetary Nebulae

New Statistical Distance Scale of Planetary Nebulae

A distance scale of planetary nebulae based on mid-infrared data

Some of the most successful statistical methods for obtaining distances of planetary nebulae (PNe) are based on their apparent sizes and radio emission intensities. These methods have the advantage of being "extinction-free" and are especially suited to be applied to PNe situated at large distances. A similar method, based on the mid-infrared (MIR) emission of PNe, would have the advantage of being applicable to the large databases created after the various all-sky or Galactic plane infrared surveys, such as IRAS, MSX, ISOGAL, GLIMPSE, etc. In this work we propose a statistical method to calculate the distance of PNe based on the apparent nebular radius and the MIR flux densities. We show that the specific intensity between 8 and 21 micron is proportional to the brightness temperature T_b at 5 GHz. Using MIR flux densities at 8, 12, 15 and 21 microns from the MSX survey, we calibrate the distance scale with a statistical method by Stanghellini et al. 2008 (SSV). The database used in the calibration consisted of 67 Galactic PNe with MSX counterparts and distances determined by SSV. We apply the method to a sample of PNe detected at 8 microns in the GLIMPSE infrared survey, and determine the distance of a sample of PNe located along the Galactic plane and bulge.

A new statistical distance scale of planetary nebulae based on MSX data

A new statistical distance scale of planetary nebulae based on MSX data

White Dwarf Central Stars of Planetary Nebulae

Results of a spectroscopic investigation of central stars of old planetary nebulae (PNe) are reported. The evolutionary status of the central stars is discussed and it is shown that most are in good agreement with standard post-AGB evolution, but some are best explained as descendents from the first RGB after binary interaction. The distance scale of PNe is discussed.

The distance scale of planetary nebulae

By collecting distances from the literature, a set of 73 planetary nebulae with mean distances of high accuracy is derived. This sample is used for recalibration of the mass-radius relationship, used by many statistical distance methods. An attempt to correct for a statistical peculiarity, where errors in the distances influences the mass{radius relationship by increasing its slope, has been made for the rst time. Distances to PNe in the Galactic Bulge, derived by this new method as well as other statistical methods from the last decade, are then used for the evaluation of these methods as distance indicators. In order of achieving a Bulge sample that is free from outliers we derive new criteria for Bulge membership. These criteria are much more stringent than those used hitherto, in the sense that they also discriminate against background objects. By splitting our Bulge sample in two, one with optically thick (small) PNe and one with optically thin (large) PNe, we nd that our calibration is of higher accuracy than most other calibrations. Dierences between the two subsamples, we believe, are due to the incompleteness of the Bulge sample, as well as the dominance of optical diameters in the \thin sample and radio diameters in the \thick sample. Our nal conclusion is that statistical methods give distances that are at least as accurate as the ones obtained from many individual methods. Also, the \long distance scale of Galactic PNe is conrmed.

The distances of planetary nebulae: A scaling factor based upon radial velocities

We have used the observed radial velocities of planetary nebulae, and the galactic rotation curve to define a new distance scale for planetary nebulae. Care has been taken to restrict the analysis to sources in which distance non-linearities are minimised, and for which distortion of the distance scale is likely to be small. We conclude, as a result, that the so-called “long” distance scales are the most valid, and that various “shorter” scales are unlikely to be correct. The primary systematic errors in this procedure derive from uncertainties in the galactic rotation profile, and in Θ0 and R0. Such errors are less than those normally associated with PN distance determinations.

Expansion distances of Planetary Nebulae

The distances of planetary nebulae are discussed as derived from their angular expansions and radial expansion velocities. An assessment is given of distances derived by this method both at optical and radio wavelengths. The recent VLA radio data show promise in establishing a more accurate distance scale for planetary nebulae.

A new distance scale of planetary nebulae

A new scale of distances to planetary nebulae is proposed. This scale is free of the common a priori assumptions about the evolution of the nebulae and exciting stars. The recently found regression relationship between radius and temperature of the central star is employed. As the initial data for distance finding, we use the radio flux density of the nebulae and the stellar magnitude of the nucleus, or one of these parameters and the central star temperature. The distances to 75 planetary nebulae have been calculated, and their linear dimensions and hydrogen atom concentrations have been determined. It is found that the ionized masses of the planetary nebulae range from 10−3 M⊙ to 1.419M⊙.

The Distances of PN and the Galactic Rotation Curve

The problem of determining the distance scale for planetary nebulae (PN) is approached through the kinematics of this subpopulation in the galaxy. To this end, we have compiled a catalogue of all known radial velocities for 457 galactic PN with standardized error statistics. External (calibration?) errors of the same magnitude as internal spectral line deviations are noted.

On the radio distance scale for planetary nebulae

On the radio distance scale for planetary nebulae

The Distance Scale of Planetary Nebulae

The spectacular success of the so-called Shklovsky method of finding distances to planetary nebulae which are optically thin to the Lyman continuum (Shklovsky 1956; see also Minkowski and Aller 1954) has produced within us a rather breath-taking boldness. Following the careful application of this method to more than 600 planetaries by Cahn and Kaler (1971), we now have the audacity to use planetaries as reliable distance indicators to derive an improved model of our own galaxy (Cahn 1976), trace the evolution of stars in their post-giant stages (O'Dell 1974, Cahn and Wyatt 1976), and even determine distances to other stellar systems (Ford, Jenner, and Epps 1973). At the Tatranská Lomnica meeting 10 years ago, there seemed little hope that one day soon planetary nebulae distances would become reliable. That day is near if not here already.

A New Synthetic Distance Scale for Planetary Nebulae

A new distance scale is provided for the Planetary Nebulae (PN). It combines thirteen lists, published between 1950 and 1976, for which the distances have been recalibrated with the aid of a large number of individual distances Dind: 19 values were selected from among individual distances already published, and 62 new distances have been calculated from kinematic and absorption laws.

A Distance Scale for Planetary Nebulae Based on Emission-Line Fluxes.

A Distance Scale for Planetary Nebulae Based on Emission-Line Fluxes.