Galaxies
Astro 322
Winter 2011
Feb. 7
Monday, February 7, 2011
normal spirals
irregu
lars
ellipticals
lenticulars
barred spirals
“tuning-fork” diagram
Monday, February 7, 2011
Monday, February 7, 2011
Galaxies classification:
key differences: total mass, gas/stars ratio,
mass-to-light ratio
gas/stars ratio is connected with:
•flatness of galaxy
•current SFR
•ages of stellar population, colors of stars
•spiral structure
Monday, February 7, 2011
Surface brightness, isophote, profile
15
µB
Night sky at 22.7
20
25
30
radius
µB
R1/4
Vaucouleurs law
Monday, February 7, 2011
elliptical galaxies sequence: oblate/prolate
classification based on ratio 10 (1-b/a) of galaxy’s isophotes
M87 E0p
M32 E2
NGC 4660, E7
107 - 1013 Msun
Monday, February 7, 2011
M110 E6
elliptical galaxies sequence: oblate/prolate
classification based on ratio 10 (1-b/a) of galaxy’s isophotes
M87 E0p
M32 E2
NGC 4660, E7
107 - 1013 Msun
Monday, February 7, 2011
M110 E6
elliptical galaxies sequence: oblate/prolate
classification based on ratio 10 (1-b/a) of galaxy’s isophotes
M87 E0p
M32 E2
NGC 4660, E7
107 - 1013 Msun
Monday, February 7, 2011
M110 E6
lenticular galaxies: some dust/gas, no spiral arms
NGC 2787
SB0
Spindle galaxy,
S0
NGC 4526,
SB0
Monday, February 7, 2011
lenticular galaxies: some dust/gas, no spiral arms
Cartwheel galaxy (S pec ring)
Monday, February 7, 2011
Supergiant ellipticals/lenticular: centrally dominant (cD)
more diffuse, larger haloes, more akin to lenticular
IC 1101 Galaxy:
diameter 1700 kpc,1014 stars
Monday, February 7, 2011
NGC 1275: cD galaxy + high velocity system
origin of cold filaments is unknown
dwarf ellipticals (dE)
sometimes mentioned to be intermediate between GC and E
not fully correct: dark matter
M32
Andromeda
(M31)
M110
Monday, February 7, 2011
dwarf ellipticals (dE)
sometimes mentioned to be intermediate between GC and E
not fully correct: dark matter
M32
Andromeda
(M31)
M110
M110 Е5
Monday, February 7, 2011
compact ellipticals: small sizes and high stellar densities
M32
Andromeda
(M31)
M110
(By Lanoue)
Monday, February 7, 2011
compact ellipticals: small sizes and high stellar densities
a small spiral in the past?
M32
compact elliptical
Andromeda
(M31)
M110
(By Lanoue)
Monday, February 7, 2011
dwarf spheroids (dSph): lower L than in dE, only sattelites
A distinct class by stellar population and profile
NGC 147
Different by brightness profile from
E and dE, closer to GC however
have dark matter
Monday, February 7, 2011
Sculptor
Vast majority of dE and dSph are
closer by properties to Irr & late
type galaxies than to E!
Spiral galaxies: unbarred, spiral arm sequence
from tightly wound arms to loosely wound arms
M81, Sab (Gendler)
Monday, February 7, 2011
M31, Sb
M101, Scd
Spiral galaxies: barred vs unbarred.
a: small body, more tightly wound arms
M104,
Sombrero
Sa
NGC 6782
SBa
Monday, February 7, 2011
Spiral galaxies: barred vs unbarred.
a: small body, more tightly wound arms
M104,
Sombrero
Sa
NGC 6782
SBa
Monday, February 7, 2011
Spiral galaxies: a-b
Black eye
Sab
the interstellar gas in the
outer regions of M64 rotates
in the opposite direction from
the gas and stars in the inner
regions
Monday, February 7, 2011
Spiral galaxies: barred vs unbarred
b subtype
M81, Sab
NGC1300, SBbc
Monday, February 7, 2011
Spiral galaxies: barred vs unbarred
c: loosely wound arms
Pinwheel galaxy, Scd
NGC 3319, SBc
Monday, February 7, 2011
Spiral galaxies: barred vs unbarred
d: diffuse, broken arms made up of individual stellar clusters and nebulae;
very faint central bulge
M82, Cigar galaxy, Sd
(used to be Irr in the past,
near IR showed 2 spiral arms)
NGC 2805, SBd
Monday, February 7, 2011
Spiral galaxies: barred vs unbarred
d: diffuse, broken arms made up of individual stellar clusters and nebulae;
very faint central bulge
M82, Cigar galaxy, Sd
(used to be Irr in the past,
near IR showed 2 spiral arms)
NGC 2805, SBd
Monday, February 7, 2011
Spiral galaxies: m - Magellanic spirals
with one spiral arm
NGC 5398, SBdm
NGC 55, SBm
Monday, February 7, 2011
Spiral galaxies: unbarred with ring
in such galaxies usually gas counterrotating with respect to stars
NGC 7742 SA(r)b
Monday, February 7, 2011
Ring galaxies
Hoag’s object
NGC 4650A
Polar-ring
galaxy
Monday, February 7, 2011
Spiral galaxies: grand design
prominent and well-defined spiral arms ~10%
M51 SABbc
Whirlpool galaxy
Monday, February 7, 2011
Flocculent galaxies:
functional opposite of the grand design spiral galaxy ~30%
patchy, with discontinuous spiral arms
NGC 4414, SAc
the rest of galaxies are multi arm galaxies, ~60%
Monday, February 7, 2011
MIlky Way
Monday, February 7, 2011
MIlky Way
SBb/SBc
grand design
Monday, February 7, 2011
Irregular galaxies: Irr I (Hubble classification)
have some structure
subtyped in Sm (if have some spiral structure) or Im
LMC -> SBm
SMC -> Im
Monday, February 7, 2011
Irregular galaxies: Irr I (Hubble classification)
have some structure
subtyped in Sm (if have some spiral structure) or Im
LMC -> SBm
SMC -> Im
Monday, February 7, 2011
Irregular galaxies: Irr I (Hubble classification)
have some structure
subtyped in Sm (if have some spiral structure) or Im
LMC -> SBm
SMC -> Im
Monday, February 7, 2011
Irregular galaxies: Irr II (Hubble classification)
no any structure
NGC 4485
(Hubble & Chandra)
hosts ULXs
Monday, February 7, 2011
Irregular galaxies: dIrr
dwarf irregular: very important for overal galaxy evolution. Low Z. Lots of gas.
Saggitarius
Sextans A
Monday, February 7, 2011
Monday, February 7, 2011