Física e Astrofísica do Meio Interestelar

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Ivan S. Ferreira, 05/11/2014 Instituto de Física, UnB

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Sumário

• Dia 1:

- Motivação geral

- Evolução do meio interestelar

- Dinâmica e Fases

• Dia II:

- Processos de Emissão de radiação

- Alguns casos especiais

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Fases do ISM

• Fases:

- Dark Clouds (T = 10 K; n =106 cm-3)

- Diffuse Molecular Clouds (T = 80 K; n = 100 cm-3 )

- Neutral Gas (T = 100 K, n = 1,0 cm-3)

- Warm neutral gas (T = 6000 K, n = 0,02 cm-3)

- Ionized gas (T = 104 K, n = 0,1 cm-3)

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-4 -2 0 +2 +4 +6 log n (cm-3₎

6 4 2 0 L o g T ( K ) HII regions Warm/hot molecular cores Cold dark clouds Globules HI clouds Intercloud gas Coronal gas

2 3 4

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-2 0 +2 log n (cm-3₎

lo g P 12,000K Coronal gas 10,000K WIM

Ionized gas9,000K

7,500K

3,000K

1,000K 5,000K

unstable

Molecules and dust

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Processos de emissão de radiação

• Linhas espectrais de emissão e absorção;

• Contínuo e difuso:

- Síncrotron;

- Livre-livre;

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Linhas espectrais

Flux density (10

–13

W

m

–2 µm –1 )

Wavelength (µm)

Orion Bar (H2S1) NGC 7027 C H stretch _Combination

modes

C C stretch

CH in-plane bending CH out-of-plane bending Plateau 140 a 120 100 80 60 40 20 30 25 20 15 10 5

3 4 5 6 7 8 9 10 20

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Emissão - contínuo

Free - Free

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Será que temos outras fases ou componentes

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Estrutura dos Grãos

Homogeneous

Core-mantle Aggregates

Carbonaceous

BCCA

BPCA

Silicate Graphite

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Poeira baseada em carbono

Molecules Molecular clusters Nanometer-sized particles

Figure 15

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Poeira baseada em silicatos

Si O

O

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Emissão da Poeira e Campo Magnético

B ﬁeld direction at 353 GHz, 1° resolution

lines: ψ rotated 90°

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Polarization in the visible

(starlight extinction by dust)

Polarization in the submm

(dust emission)

Direction of linear polarization

Non polarized

B

E_x Ey

Direction of

linear polarization

B

E_x

E_y

Polarization angle θ

V

Fraction of polarization p/τ

Polarization angle θ

S = θV - 90°

Fraction of polarization P/I

Spinning dust grain

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Interstellar cloud

Shell of embedded star/protostar

Shell of isolated evolved star

2 body gas phase reactions Surface reactions on grains Many-body gas phase reactions Surface reactions on grains Elemental condensation Many-body gas phase reactions Surface reactions on grains Elemental condensation Diatomic molecules Diatomic/ polyatomic molecules Interstellar grains Diatomic/ polyatomic molecules Interstellar grains

Further gas phase/ surface reactions

Eje ctio

n in_to the_IS

M Ejec tion into surro undi

ng c

loud

Mass-loss to

the ISM

Mass-loss to the ISM

Polyatomic molecules

Molecules/ grains in star forming clouds Molecules In clouds Grains in clouds Accretion ? Interstellar grains Molecules in non-star forming clouds

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Será que conseguimos fazer isso em

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Plasmas empoeirados

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Qual seria a conseqüência de um alinhamento destes

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FIG. 1.ÈFrequency dependence of rms foreground Ñuctuations, shown for four di†erent Galactic latitude slices. Squares show DIRBE-correlated

emission (Foreground X), triangles H82-correlated emission (synchrotron), and circles Ha-correlated emission (free-free) for four Galactic latitude slices

(0¡È10¡, 10¡È20¡, 20¡È30¡, and 30¡È40¡). The free-free curve is seen to lie below Foreground X in all cases, typically by about an order of magnitude.

Foreground X therefore cannot be dominated by free-free emission. The corresponding curves represent the best-Ð_{t models. The 10 and 15 GHz points are}

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Emissão anômala em outras galáxias

4 Scaife et al.

Synchrotron + free–free + absorbed free–free Synchrotron + free–free + spinning dust

0.001 0.002 0.005 0.01

Fν

(Jy)

Fν

(Jy)

1 2 5 10 20 50 100

ν(GHz)

0 5·1034

1·1035

1.5·1035

2·1035

2.5·1035

3·1035

0.001 0.002 0.005 0.01

Fν

(Jy)

Fν

(Jy)

1 2 5 10 20 50 100

ν(GHz)

0 2·1036

4·1036

6·1036

8·1036

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ﬁtted

A'signiﬁcant'number'of'sources'(28)'have'a'very'strong' “detec,on”'of'excess'emission'at'~40Q60'GHz'that'is'

wellQﬁfed'by'spinning'dust'emission'

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Objetos com SPD

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Que tipo de medida de Spinning Dust já foi

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• Power supplies: Computer controlled electrical power supplies for the

electrodes to provide AC voltage (V_ac ~ 100-2000V, at f_ac~ 10-1000 Hz), DC

voltage (V_dc ~ 0.01 to 100 V), and a high DC voltage (V_h ~ 0-1000V).

• Electrodynamic balance: Top and bottom electrodes, and a ring electrode, of hemispherical

configuration enclosed in a chamber with appropriate viewing ports.

• Particle injector : A device to inject an inductively charged particle (positive or

negative) of known composition and density in the balance through a suitable port at the top (Spann et al., 2002 .

Particle imaging system: A He-Ne laser and an optical system to project a magnified image of the levitated particle on a monitor.

Fig. 3

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Resultado do experimento

Fig. 6. Variations in the rotation rates of a

3.9 µm SiC particle as

a function of pressure.

Fig. 7. Variations in the rotation rates of a x.x9

µm SiC particle as a

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O que nós

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Para mais informações:

labcosmologiaunb.org