A NEW PLANETARY NEBULA.

The occurrence of planetary nebulae (PNe) in globular clusters (GCs) provides an excellent chance to study low-mass stellar evolution in a special (low-metallicity, high stellar density) environment. We report a systematic spectroscopic survey for the [O iii] 5007 Å emission line of PNe in 1469 Virgo GCs and 121 Virgo ultra-compact dwarfs (UCDs), mainly hosted in the giant elliptical galaxies M87, M49, M86, and M84. We detected zero PNe in our UCD sample and discovered one PN ( ) associated with an M87 GC. We used the [O iii] detection limit for each GC to estimate the luminosity-specific frequency of PNe, α, and measured α in the Virgo cluster GCs to be . The value of α in the Virgo GCs is among the lowest reported in any environment, due in part to the large sample size, and it is 5–6 times lower than that for the Galactic GCs. We suggest that α decreases toward brighter and more massive clusters, sharing a similar trend as the binary fraction, and the discrepancy between the Virgo and Galactic GCs can be explained by the observational bias in extragalactic surveys toward brighter GCs. This low but nonzero efficiency in forming PNe may highlight the important role played by binary interactions in forming PNe in GCs. We argue that a future survey of less massive Virgo GCs will be able to determine whether PN production in the Virgo GCs is governed by an internal process (mass, density, binary fraction) or if it is largely regulated by the external environment.

During an integral-field spectroscopic study of stars in the massive young open cluster NGC 1866 in the Large Magellanic Cloud, we serendipitously discovered a faint planetary nebula (PN). We designate it “Ka LMC 1,” and find that its location near the cluster center, along with the agreement of its radial velocity with that of the cluster, imply a high probability of membership in NGC 1866. The 200 Myr age of the cluster indicates that the PN’s progenitor star had an initial mass of about 3.9 M ⊙ . The integrated spectrum of Ka LMC 1 shows strong emission lines of [N ii ], consistent with it being a “Type I” nitrogen-rich PN. The nebula exhibits a classical ring morphology, with a diameter of ∼6″, corresponding to an advanced expansion age of about 18,000 yr. Archival images of NGC 1866 obtained with the Hubble Space Telescope reveal a faint blue central star. Comparison of the star’s luminosity with predictions from one set of theoretical post-asymptotic-giant-branch evolutionary tracks (for single stars) implies an age roughly consistent with the dynamical age of the PN, but the agreement with alternative modern tracks is much poorer. Analysis of the emission-line spectrum suggests considerable dust extinction within the nebula; however the central star possibly suffers little reddening because we may be viewing it nearly pole-on in a bipolar PN. Our accidental discovery was made using data that are not ideal for study of Ka LMC 1; we suggest several avenues of future targeted studies that would provide valuable and nearly unique new information for constraining models of late stellar evolution.

Using a slitless spectroscopy method with (a) the 8.2 m Subaru telescope and its FOCAS Cassegrain spectrograph, and (b) the ESO Very Large Telescope (VLT) unit 1 (Antu) and its FORS2 Cassegrain spectrograph, we have detected 326 planetary nebulae (PNs) in the giant Virgo elliptical galaxy NGC 4649 (M 60), and we have measured their radial velocities. After rejecting some PNs more likely to belong to the companion galaxy NGC 4647, we have built a catalog with kinematic information for 298 PNs in M 60. Using these radial velocities we have concluded that they support the presence of a dark matter halo around M 60. Based on an isotropic, two-component Hernquist model, we estimate the dark matter halo mass within 3$R_{\rm e}$ to be 4$\times10^{11} M_{\odot}$, which is almost one half of the total mass of about $10^{12} M_{\odot}$ within 3$R_{\rm e}$. This total mass is similar to that estimated from globular cluster, XMM-Newton and Chandra observations. The dark matter becomes dominant outside. More detailed dynamical modeling of the PN data is being published in a companion paper. We have also measured the $m$(5007) magnitudes of many of these PNs, and built a statistically complete sample of 218 PNs. The resulting PN luminosity function (PNLF) was used to estimate a distance modulus of 30.7$\pm$0.2 mag, equivalent to 14$\pm$1 Mpc. This confirms an earlier PNLF distance measurement, based on a much smaller sample. The PNLF distance modulus remains smaller than the surface brightness fluctuation (SBF) distance modulus by 0.4 mag.

The stellar kinematics of the discs of S0 galaxies (as obtained using planetary nebulae, PNe, and integrated stellar light data) is comparable to that of spiral galaxies, with similar flat rotation curves and falling velocity dispersion profiles, but they present a larger amount of random motions. The only other tracer available to probe the kinematics of individual early-type galaxies are globular clusters (GCs). GCs’ formation is intimately connected to a galaxy major star forming event(s) and GCs are, therefore, good proofs of galaxy formation histories. We directly compare a sample of PNe, GCs, and stellar velocities out to 4 effective radii, in the S0 galaxies NGC 2768 and NGC 1023. In particular, we test a new method for studying GC properties and we find that these two lenticular galaxies are consistent with being formed through different formation mechanisms.

The globular cluster (GC) system of our Galaxy contains four planetary nebulae (PNe): K 648 (or Ps 1) in M15, IRAS 18333-2357 in M22, JaFu 1 in Pal 6, and JaFu 2 in NGC 6441. Because single-star evolution at the low stellar mass of present-epoch GCs was considered incapable of producing visible PNe, their origin presented a puzzle. We imaged the PN JaFu 1 with the Hubble Space Telescope (HST) to obtain photometry of its central star (CS) and high-resolution morphological information. We imaged IRAS 18333-2357 with better depth and resolution, and we analyzed its archival HST spectra to constrain its CS temperature and luminosity. All PNe in Galactic GCs now have quality HST data, allowing us to improve CS mass estimates. We find reasonably consistent masses between 0.53 and 0.58 M ⊙ for all four objects, though estimates vary when adopting different stellar evolutionary calculations. The CS mass of IRAS 18333-2357, though, depends strongly on its temperature, which remains elusive due to reddening uncertainties. For all four objects, we consider their CS and nebula masses, their morphologies, and other incongruities to assess the likelihood that these objects formed from binary stars. Although generally limited by uncertainties (∼0.02 M ⊙) in post-AGB tracks and core mass versus luminosity relations, the high-mass CS in K 648 indicates a binary origin. The CS of JaFu 1 exhibits compact, bright [O iii] and Hα emission, like EGB 6, suggesting a binary companion or disk. Evidence is weaker for a binary origin of JaFu 2.

Stars are the most fundamental components of the visible universe. They provide reference points in the sky, distance markers for cosmologists and tracers of dark matter; serve as the basis for understanding the composition and origin of our solar system; and are companions used to find planets, brown dwarfs, and black holes. Our ability to understand and to use stars effectively for these and other applications depends on knowledge of stellar life cycles. Our view of stellar evolution has changed and progressed rapidly in the past 5 to 10 years, due in part to technological advances, including bigger and better charge-coupled devices, improved ground-based telescopes such as Keck I and II, and continued spectacular results from orbiting satellites such as the Hubble Space Telescope, the Rontgen X-ray Satellite, and the Solar Heliospheric Observatory. Given this progress, the recent discoveries of extrasolar planets (see News story on p. [1336][1]) and brown dwarfs, and the possibility that we may soon identify a black hole and a source for gamma ray bursts using the characteristics of star-like objects near these phenomena, it seems fitting to highlight some advances in stellar research in the nine Articles in this special issue. A star is born by the gravitational collapse of a cloud of dust and gas. If the condensing spherical mass cannot grow large enough, then it slowly gets colder and fades, becoming a brown dwarf. If it grows enough to sustain hydrogen fusion, a main sequence star, like our sun, is formed. Eventually hydrogen is exhausted, the star expands to a red giant as it feeds off other nuclear reactions, and finally the red giant collapses into a small, dense white dwarf, when these reactions cease. In some cases, the collapsing star throws off excess mass as a gaseous envelope, called a planetary nebula. More massive stars tend to die in rapid energetic outbursts called supernovae explosions that produce white dwarfs; or if the remnant core is too massive, collapse continues until most energetic particles are converted to neutrons that stabilize the core into a neutron star. The most massive stars, with the shortest lifetimes and the most energetic supernovae explosions, cannot collapse into white dwarfs or neutron stars; instead, they collapse into an even smaller, denser core from which not even light can escape: a black hole. The first five Articles discuss the early part of the stellar cycle. Kulkarni (p. [1350][2]) focuses on the direct detection of a brown dwarf and discusses how brown dwarfs may be a link between planets and stars. O'Dell and Beckwith (p. [1355][3]) describe the dynamics of stellar birth, focusing on star-forming regions in the Orion Nebula, which show that young stars do not just collapse into spheres of gas but produce jets, winds, and possible planet-forming disks of dust. Arnett and Bazan (p. [1359][4]) discuss the latest progress in understanding nucleosynthetic processes, including the identification of presolar grains in meteorites and the use of high-energy density laser experiments to simulate thermonuclear reactions. Neuhauser (p. [1363][5]) focuses on the x-ray emissions from protostars, which can be seen through molecular clouds that surround protostars. Many protostars are binaries and interact with the circumstellar disk, possibly allowing planet formation within the disks. Burgarella (p. [1370][6]) reviews globular clusters, which are regions of colliding galaxies that produce bursts of star-forming regions encased in dense envelopes of gas. Globular clusters help us understand galaxy formation and the evolution and age of the universe. The death of stars is perhaps most obvious in supernovae explosions. Supernova 1987A, because it was discovered early in its explosive history and was relatively close to Earth, has provided a wealth of information about the chemical and physical evolution of supernovae. Chevalier (p. [1374][7]) reviews the progress made in understanding Type II supernovae, particularly 1987A and 1993 J. Nomoto, Iwamoto, and Kishimoto (p. [1378][8]) discuss Type Ia supernovae, which are believed to represent the thermonuclear explosions of accreting white dwarfs and are used to estimate the age of the universe and distance to its edge. On the quieter side of stellar death, Weinberger and Kerber (p. [1382][9]) describe the diverse morphologies of and applications for planetary nebulae. Spectroscopic observations of planetary nebulae in the halos of galaxies confirm that we cannot account for most of the dark matter in the universe. Finally, Kaaret and Ford (p. [1386][10]) review x-ray binaries, which consist of a neutron star or black hole and a compact star. Understanding how material flows from the star to the black hole will help to identify the event horizon of a black hole. [1]: /lookup/doi/10.1126/science.276.5317.1336 [2]: /lookup/doi/10.1126/science.276.5317.1350 [3]: /lookup/doi/10.1126/science.276.5317.1355 [4]: /lookup/doi/10.1126/science.276.5317.1359 [5]: /lookup/doi/10.1126/science.276.5317.1363 [6]: /lookup/doi/10.1126/science.276.5317.1370 [7]: /lookup/doi/10.1126/science.276.5317.1374 [8]: /lookup/doi/10.1126/science.276.5317.1378 [9]: /lookup/doi/10.1126/science.276.5317.1382 [10]: /lookup/doi/10.1126/science.276.5317.1386

We present a kinematic analysis of the globular cluster(GC) system in M31. Using the photometric and spectroscopic database of 504 GCs, we have investigated the kinematics of the M31 GC system. We find that the all GC system shows strong rotation, with ro

The objects from which the structure and the kinematical properties of the nuclear region and the halo can be derived are in general those classified as population II objects: the RR Lyrae variables, population II Cepheids, RV Tauri variables, long-period variables with periods near 200 days, novae, planetary nebulae, bright red giants as found in globular clusters, and the blue stars found near the galactic poles which are probably similar to those found in globular clusters.

We have obtained spectra for globular cluster candidates in M104 with LDSS-2 on the William Herschel Telescope, confirming 34 objects as M104 globular clusters.We find a cluster velocity dispersion of ∼ 260 km/sec, and the Projected Mass Estimator gives a mass of 5.0 (3.5,6.7)× 10 11 M ⊙ for M104 within a projected radius of ∼ 330 ′′ (14 kpc for D=8.55 Mpc).Our best estimate for the mass-to-light ratio is M/L VT = 16 +5.5 -5.0 within the same radius.Considering all of the possible sources of uncertainty, we find a lower limit of M/L V = 5.3, which is larger than the M/L V found from rotation curve analyses inside 180 ′′ .We thus conclude that the mass-to-light ratio increases with radius, or in other words that M104 possesses a dark matter halo.There is a marginal detection of rotation in the M104 cluster system at the 92.5% confidence level; larger samples will be needed to investigate this possibility.Interestingly, the M104 globular cluster and planetary nebulae (PNe) kinematics are roughly consistent inside ∼ 100 ′′ .Finally, we find a mean cluster metallicity of [Fe/H] = -0.70 ± 0.3, which is more typical of clusters in gE/cD galaxies than it is of clusters in other spirals.

We create dynamical models of the massive elliptical galaxy, NGC 4649, using the N-body made-to-measure code, NMAGIC, and kinematic constraints from long-slit and planetary nebula (PN) data. We explore a range of potentials based on previous determinations from X-ray observations and a dynamical model fitting globular cluster (GC) velocities and a stellar density profile. The X-ray mass distributions are similar in the central region but have varying outer slopes, while the GC mass profile is higher in the central region and on the upper end of the range further out. Our models cannot differentiate between the potentials in the central region, and therefore if non-thermal pressures or multi-phase components are present in the hot gas, they must be smaller than previously inferred. In the halo, we find that the PN velocities are sensitive tracers of the mass, preferring a less massive halo than that derived from the GC mass profile, but similar to one of the mass distributions derived from X-rays. Our results show that the GCs may form a dynamically distinct system, and that the properties of the hot gas derived from X-rays in the outer halo have considerable uncertainties that need to be better understood. Estimating the mass in stars using photometric information and a stellar population mass-to-light ratio, we infer a dark matter mass fraction in NGC 4649 of ~0.39 at 1Re (10.5 kpc) and ~0.78 at 4Re. We find that the stellar orbits are isotropic to mildly radial in the central ~6 kpc depending on the potential assumed. Further out, the orbital structure becomes slightly more radial along R and more isotropic along z, regardless of the potential assumed. In the equatorial plane, azimuthal velocity dispersions dominate over meridional velocity dispersions, implying that meridional velocity anisotropy is the mechanism for flattening the stellar system.

Section I. Halo White Dwarfs and Galactic Structure. Old Ultracool White Dwarfs as Cosmological Probes. Number counts of white dwarfs: the impact of GAIA. Influence of Metallicity in the Determination of the Age of Halo White Dwarfs. Cool Halo White Dwarfs from GSCII. Dark halo baryons not in ancient white dwarfs? White Dwarfs in 2QZ and Sloan Surveys. White Dwarfs and Cataclysmic in the FBS. White Dwarfs in Globular Clusters. Core/Envelope Symmetry in Pulsating White Dwarfs Stars. A Search for Variability in Cool White Dwarf Stars. Planetary Nebulae and the Galactic Bulge. Section II. Type Ia Supernovae. Type Ia Supernovae and Cosmology. The Progenitors of Type Ia Supernovae. Progenitors of Supernovae Type Ia. Polulation synthesis for progenitors of type Ia supernovae. How far can we trust SNE Ia as Standard Candles? Kirshner on White Dwarfs. Supernovae. and Cosmology. Section III. Cataclysmic Variables and White Dwarf Accretion. Accretion in Cataclysmic Variable Stars. White Dwarfs in Cataclysmic Variables: Probes of Accretion History. Intermediate Polars in Low States. Chemical Abundances of WDs in CVs. AM CVn Stars in the UCT CCD CV Survey. TUG Observations of V2275 Cyg, RW Umi, PX And and FO Per. The Possible Identification of Two Hibernating Novae. Evidence for large superhumps in TX Col and V4742 Sgr. Concluding remarks.

The relative abundances of H, He, Ne, O, and N have been determined in thirty planetary nebulae of widely-differing kinematical properties. Helium abundances are found to be affected by incomplete ionization of He, an effect that is strongly correlated with the abundance of S+. The He and N abundances appear to be positively-correlated, suggesting that nebular material has been contaminated through mixing with CNO-processed material. There is some evidence for a radial galactic abundance gradient in He, N, and possibly O and Ne; abundances increase toward the galactic center. This gradient is evident only from the nebulae that appear to be moving in circular orbits. All nebulae (except the previously studied planetary in the galactic halo and the one in the globular cluster M 15) have nearly the same abundances of O and Ne as galactic HII regions and the sun, and there is little correlation between these abundances and the kinematical properties of the planetaries. Apparently either Ne and O are not representative of the true heavy metal abundance, or the vast majority of planetaries belong to a metal-rich population. The latter possibility seems more likely in view of recent observations of the S++ abundances of nineteen of the nebulae, which show them to have generally solar S abundances. (Paper will appear in The Astrophysical Journal.)

view Abstract Citations (27) References (26) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Superluminous giants in Magellanic Cloud clusters. Flower, P. J. Abstract The C-M diagram of the LMC blue, globular-like cluster NGC 1866 is known to exhibit a large number of yellow- and red-core helium-burning giants. Short exposure photographic plates taken with the CTIO 4-m Ritchey-Chretien camera provide an opportunity to study the stellar content of the central regions of this cluster. In and near the core of NGC 1866, 11 superluminous giants (SLGs), apparently similar to those found in other LMC blue, globular-like clusters, have been identified. These stars lie more than 0.5 mag above the core helium-burning giants. It is proposed that SLGs are protoplanetary nebulae, i.e., stars that, having ejected their envelopes as luminous red giants, are crossing the C-M diagram toward becoming central star planetary nebulae. Publication: The Astrophysical Journal Pub Date: October 1981 DOI: 10.1086/183647 Bibcode: 1981ApJ...249L..11F Keywords: Giant Stars; Late Stars; Magellanic Clouds; Planetary Nebulae; Star Clusters; Stellar Luminosity; Globular Clusters; Star Distribution; Stellar Evolution; Stellar Magnitude; Astronomy full text sources ADS | data products SIMBAD (3)

The globular cluster M15 was observed on three occasions with the High Resolution Camera on-board Chandra in 2001 in order to investigate the X-ray source population in the cluster centre. After subtraction of the two bright central sources, four faint sources were identified within 50 arcsec of the core. One of these sources is probably the planetary nebula K648, making this the first positive detection of X-rays from a planetary nebula inside a globular cluster. Another two are identified with UV variables (one previously known), which we suggest are cataclysmic variables (CVs). The nature of the fourth source is more difficult to ascertain, and we discuss whether it is possibly a quiescent soft X-ray transient or also a CV.

We estimate the masses of elliptical galaxies out to five effective radii using planetary nebulae and globular clusters as tracers. A sample of 15 elliptical galaxies with a broad variation in mass is compiled from the literature. A distribution function-maximum likelihood analysis is used to estimate the overall potential slope, normalisation and velocity anisotropy of the tracers. We assume power-law profiles for the potential and tracer density and a constant velocity anisotropy. The derived potential power-law indices lie in between the isothermal and Keplerian regime and vary with mass: there is tentative evidence that the less massive galaxies have steeper potential profiles than the more massive galaxies. We use stellar mass-to-light ratios appropriate for either a Chabrier/KTG (Kroupa, Tout & Gilmore) or Salpeter initial mass function to disentangle the stellar and dark matter components. The fraction of dark matter within five effective radii increases with mass, in agreement with several other studies. We employ simple models to show that a combination of star formation efficiency and baryon extent are able to account for this trend. These models are in good agreement with both our measurements out to five effective radii and recent SLACS measurements within one effective radii when a universal Chabrier/KTG initial mass function is adopted.