Planetary Nebulae

Miller, Joseph Scott

doi:10.1146/annurev.aa.12.090174.001555

Cited by 23 publications

(10 citation statements)

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“…Other hydrogen emission lines, such as Lβ or Hα, are expected to be two orders of magnitude less luminous than Lα in our model (Baldwin 1977;Miller 1974). The column densities of NHI ∼ 10 20 cm −2 in the cold streams should also be detectable as Lα absorption in quasar spectra (Prochaska 1999;Wolfe, Gawiser & Prochaska 2005).…”

Section: Discussionmentioning

confidence: 78%

Gravity-driven Lyα blobs from cold streams into galaxies

Goerdt¹,

Sternberg²,

Ceverino³

et al. 2010

Monthly Notices of the Royal Astronomical Society

192

271

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We use high‐resolution cosmological hydrodynamical adaptive mesh refinement (AMR) simulations to predict the characteristics of Lyα emission from the cold gas streams that fed galaxies in massive haloes at high redshift. The Lyα luminosity in our simulations is powered by the release of gravitational energy as gas flows from the intergalactic medium into the halo potential wells. The ultraviolet UV background contributes only <20 per cent to the gas heating. The Lyα emissivity is due primarily to electron‐impact excitation cooling radiation in gas at ∼2 × 104 K. We calculate the Lyα emissivities assuming collisional ionization equilibrium at all gas temperatures. The simulated streams are self‐shielded against the UV background, so photoionization and recombination contribute negligibly to the Lyα line formation. We produce theoretical maps of the Lyα surface brightnesses, assuming that ∼85 per cent of the Lyα photons are directly observable. We do not consider transfer of the Lyα radiation, nor do we include the possible effects of internal sources of photoionization such as star‐forming regions. Dust absorption is expected to obscure a small fraction of the luminosity in the streams. We find that typical haloes of mass Mv∼ 1012–1013 M⊙ at z∼ 3 emit as Lyα blobs (LABs) with luminosities 1043–1044 erg s−1. Most of the Lyα comes from the extended (50–100 kpc) narrow, partly clumpy, inflowing, cold streams of (1–5) × 104 K that feed the growing galaxies. The predicted LAB morphology is therefore irregular, with dense clumps and elongated extensions. The integrated area contained within surface brightness isophotes of 2 × 10−18 erg s−1 cm−2 arcsec−2 is ∼2–100 arcsec2, consistent with observations. The linewidth is expected to range from 102 to more than 103 km s−1 with a large variance. The typical Lyα surface brightness profile is ∝r−1.2 where r is the distance from the halo centre. Our simulated LABs are similar in luminosity, morphology and extent to the observed LABs, with distinct kinematic features. The predicted Lyα luminosity function is consistent with observations, and the predicted areas and linewidths roughly recover the observed scaling relations. This mechanism for producing LABs appears inevitable in many high‐z galaxies, though it may work in parallel with other mechanisms. Some of the LABs may thus be regarded as direct detections of the cold streams that drove galaxy evolution at high z.

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Section: Discussionmentioning

confidence: 78%

Gravity-driven Lyα blobs from cold streams into galaxies

Goerdt¹,

Sternberg²,

Ceverino³

et al. 2010

Monthly Notices of the Royal Astronomical Society

192

271

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“…We assume an intrinsic flux ratio of R int = Hα/Hβ = 2.86, corresponding to an ionized gas temperature of T≈ 10 4 (assuming case B recombination; Miller 1974, Osterbrock 1974, Osterbrock & Martel 1992,Osterbrock & Martel 2006.…”

Section: Attenuation Mapsmentioning

confidence: 99%

Attenuation Modified by DIG and Dust as Seen in M31

Tomičić

Kreckel

Groves

et al. 2017

ApJ

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The spatial distribution of dust in galaxies affects the global attenuation, and hence inferred properties, of galaxies. We trace the spatial distribution of dust in five fields (at 0.6-0.9 kpc scale) of M31 by comparing optical attenuation with the total dust mass distribution. We measure the attenuation from the Balmer decrement using Integral Field Spectroscopy and the dust mass from Herschel far-IR observations. Our results show that M31's dust attenuation closely follows a foreground screen model, contrary to what was previously found in other nearby galaxies. By smoothing the M31 data we find that spatial resolution is not the cause for this difference. Based on the emission line ratios and two simple models, we conclude that previous models of dust/gas geometry need to include a weakly or non-attenuated diffuse ionized gas (DIG) component. Due to the variation of dust and DIG scale heights with galactic radius, we conclude that different locations in galaxies will have different vertical distributions of gas and dust and therefore different measured attenuation. The difference between our result in M31 with that found in other nearby galaxies can be explained by our fields in M31 lying at larger galactic radii than the previous studies that focused on the centers of galaxies.

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“…We cannot exclude, however, its possible origin in a planetary nebula (PN) or a proto-planetary nebula (PPN) because these also show similar bipolar morphologies in the infrared (Balick et al 1987;Kwok 1993). Recombination and forbidden line emission from hydrogen and metals, especially H α and [Oiii], are significant spectral features of a PN in the optical (Osterbrock 1964;Miller 1974). However, very weak H α and no [Oiii] emission were detected in the optical spectrum (see Fig.…”

Section: Young Stellar Object Vs Evolved Stellar Objectmentioning

confidence: 99%

The discovery based on GLIMPSE data of a protostar driving a bipolar outflow

Yuan¹,

Li²,

Huang³

et al. 2012

A&A

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We report the discovery based on GLIMPSE data of a proto-stellar system driving a bipolar outflow. The bipolar outflow closely resembles the shape of an hourglass in the infrared. The total luminosity of L total = 5507 L , derived from IRAS fluxes, indicates the ongoing formation of a massive star in this region. The spectral energy distribution (SED) of the driving source is fitted with an online SED fitting tool, which results in a spectral index of about 1.2. This, along with the presence of a bipolar outflow, suggests the detection of a Class I protostar. The driving source indicates prominent infrared excesses in color-color diagrams based on archived 2 MASS and GLIMPSE data, which is in line with an early evolutionary stage of the system.

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Planetary Nebulae

Cited by 23 publications

References 0 publications

Gravity-driven Lyα blobs from cold streams into galaxies

Gravity-driven Lyα blobs from cold streams into galaxies

Attenuation Modified by DIG and Dust as Seen in M31

The discovery based on GLIMPSE data of a protostar driving a bipolar outflow

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