Center Galactic The -...
Transcript of Center Galactic The -...
![Page 1: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/1.jpg)
I
EF
CO
DR
I
L
AI
N
RDNXAEA
ESI
I
C
M LMVA
AI
AD
R
E
LGE
5–1
The
Gal
actic
Cen
ter
![Page 2: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/2.jpg)
D.Seal/JPL
The Yale Bright Star Catalogue (9110 brightest stars)
![Page 3: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/3.jpg)
D.Seal/JPL
The Hipparcos Catalogue (118000 stars)
![Page 4: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/4.jpg)
D.Seal/JPL
The second Tycho Catalogue (2.5 million stars)
![Page 5: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/5.jpg)
![Page 6: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/6.jpg)
X
![Page 7: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/7.jpg)
I
EF
CO
DRI
L
A I
N
RDNXA
EA
ESII
C
M
LMV
A
AI
AD
R
E
L G
E
5–7
The Milky Way 6
The Night Sky, VI
Galileo Galilei (1564–1642; Sidereus
Nuncius): Telescope resolves (part of)
the milky way in stars, discovers new
stars =⇒ Milky way is not “milky”!
![Page 8: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/8.jpg)
I
EF
CO
DRI
L
A I
N
RDNXA
EA
ESII
C
M
LMV
A
AI
AD
R
E
L G
E
5–8
The Milky Way 7
The Night Sky, VII
William Herschel (1738–1822): First
attempts to determine morphology of the
Galaxy.
Note: heliocentric!
![Page 9: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/9.jpg)
I
EF
CO
DRI
L
A I
N
RDNXA
EA
ESII
C
M
LMV
A
AI
AD
R
E
L G
E
5–9
The Milky Way 8
The Night Sky, VIII
d
r
π
πsin bπ
Wilhelm Bessel (1784–1846): First
determination of a stellar parallax
reminder:
1 parsec = 3.26 Lj = 3× 1013 km
![Page 10: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/10.jpg)
W. Keel (U Alabama)
Milky way in Sagittarius
27 × 40
![Page 11: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/11.jpg)
Scutum
Ophiuchus
M16
M25
M23
M8
M22M28
M54M69
M7 NGC 6357
M21
M17
M24
M9
NGC 6723
Sagittarius
Scorpius
NGC 6334
M6
M20
W. Keel (U Alabama)
Milky way in Sagittarius
27 × 40
![Page 12: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/12.jpg)
Scutum
Ophiuchus
M16
M25
M23
M8
M28
M54M69
M7 NGC 6357
M21
M17
M24
M9
NGC 6723
Sagittarius
Scorpius
NGC 6334
M6
M20M22
W. Keel (U Alabama)
Milky way in Sagittarius
27 × 40
![Page 13: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/13.jpg)
M22, KPNO (N.A.Sharp, REU program/NOAO/AURA/NSF)
![Page 14: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/14.jpg)
18
16
14
12
10
Temperature
0 0.5 1(b−y)
V
Lum
inos
ity
Richter et al., 1999, A&A 350, 476 M22, KPNO (N.A.Sharp, REU program/NOAO/AURA/NSF)
![Page 15: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/15.jpg)
18
16
14
12
10
Temperature
−20 −10 0 10 20 30 40X [kpc]
−30
−20
−10
0
10
20
30
Z [k
pc]
0 0.5 1(b−y)
V
Lum
inos
ity
RR Lyrae
M22 has a distance of 3.2kpc
Richter et al., 1999, A&A 350, 476 M22, KPNO (N.A.Sharp, REU program/NOAO/AURA/NSF)
![Page 16: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/16.jpg)
18
16
14
12
10
Temperature
−20 −10 0 10 20 30 40X [kpc]
−30
−20
−10
0
10
20
30
Z [k
pc]
0 0.5 1(b−y)
V
Lum
inos
ity
RR Lyrae
Galactic center has a distance of 8kpc
Richter et al., 1999, A&A 350, 476 M22, KPNO (N.A.Sharp, REU program/NOAO/AURA/NSF)
![Page 17: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/17.jpg)
1kpc
Scutum
Ophiuchus
M16
M25
M23
M8
M22M28
M54M69
M7 NGC 6357
M21
M17
M24
M9
NGC 6723
Sagittarius
Scorpius
NGC 6334
M6
M20
W. Keel (U Alabama)
Milky way in Saggitarius
27 × 40
Distance: 8 kpc
=⇒ 1 ∼ 140 pc
=⇒ 1′ ∼ 2 pc
=⇒ 1′′ ∼ 0.03 pc
![Page 18: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/18.jpg)
Scutum
Ophiuchus
M16
M25
M23
M8
M22M28
M54M69
M7 NGC 6357
M21
M17
M24
M9
NGC 6723
Sagittarius
GalacticCenter
Scorpius
X
NGC 6334
M6
M20
1 kpc
W. Keel (U Alabama)
Milky way in Saggitarius
27 × 40
Distance: 8 kpc
=⇒ 1 ∼ 140 pc
=⇒ 1′ ∼ 2 pc
=⇒ 1′′ ∼ 0.03 pc
![Page 19: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/19.jpg)
I
EF
CO
DRI
L
A I
N
RDNXA
EA
ESII
C
M
LMV
A
AI
AD
R
E
L G
E
5–19
The Milky Way 18
Milky Way as a Galaxy
Galactic CenterX
12 kpc
Sun
208 km/s
8 kpc
220 Mill years/revolution
Luminosity: ∼ 2× 1010 LMass: ∼1011 M (radiating)
∼1012 M (total)
Stellar density:
∼ 0.3 M pc−3
1 M = 2× 1033 g = 2× 1030 kg,1 L = 4× 1033 erg s−1 = 4× 1026 W
M83: ESO [VLT ANTU+FORS1]
![Page 20: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/20.jpg)
I
EF
CO
DRI
L
A I
N
RDNXA
EA
ESII
C
M
LMV
A
AI
AD
R
E
L G
E
5–19
The Milky Way 19
Milky Way as a Galaxy
Galactic CenterX
12 kpc
Sun
208 km/s
8 kpc
220 Mill years/revolution
Luminosity: ∼ 2× 1010 LMass: ∼1011 M (radiating)
∼1012 M (total)
Stellar density:
∼ 0.3 M pc−3
1 M = 2× 1033 g = 2× 1030 kg,1 L = 4× 1033 erg s−1 = 4× 1026 W
12 kpc8 kpc
X
2kpc
600 pc
NGC 4565: W. McLaughlin
![Page 21: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/21.jpg)
Problem: strong extinction due to dust
(AV ∼ 30 mag: 1012 times reduction in the optical!)
=⇒ Multiwavelength astronomy!
![Page 22: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/22.jpg)
Infra red: Dust becomes transparent!
2MASS: 3 IR Bänder: J (1.25 µm), H (1.65 µm), Ks (2.17µm)
![Page 23: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/23.jpg)
2MASS: inner 60 × 45
![Page 24: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/24.jpg)
2MASS/MSX: Inner 4 × 2
2MASS (J [1.25 µm], red), (K [2.17 µm], green), MSX (A [6–11µm], blue)
![Page 25: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/25.jpg)
X
![Page 26: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/26.jpg)
I
EF
CO
DRI
L
A I
N
RDNXA
EA
ESII
C
M
LMV
A
AI
AD
R
E
L G
E
5–25
The Path to the Galactic Center 6
The Inner kpc
70 pc× 70 pc, VLA (F. Yusef-Zadeh et al., 1982–1984)c©NRAO/AUI
Radio source Sgr A:
Sgr A (West) (Arc): 5′′ (=0.2 pc) broad
radio filaments, part of a much larger
Ω-shaped structure ⊥ galactic plane.
polarized, steep radio spectrum =⇒
synchrotron radiation (nonthermal
electrons; ne(E) ∝ E−p)!caused by shocks from supernovae?
![Page 27: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/27.jpg)
Sgr A West (“spiral”):
2 pc diameter,
∼ 60 M ionized gas, shaped by
tidal forces
(probably influence of mG B-field),
northern arm falls on center, east
and south arms rotate.
around Sgr A West: circumnuclear
disk of molecular gas, (r ∼ 2 pc).
total mass accretion rate onto
Sgr A∗:
∼ 3× 10−6 M yr−1
Sgr A (3.6 cm, courtesy K.Y. Lo/NRAO/AUI)
![Page 28: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/28.jpg)
armsouthern
easternarm
Sgr A*
northernarm
IRS 8
IRS 7
ringcircumnuclear
Sgr A West (“spiral”):
2 pc diameter,
∼ 60 M ionized gas, shaped by
tidal forces
(probably influence of mG B-field),
northern arm falls on center, east
and south arms rotate.
around Sgr A West: circumnuclear
disk of molecular gas, (r ∼ 2 pc).
total mass accretion rate onto
Sgr A∗:
∼ 3× 10−6 M yr−1
Sgr A (3.6 cm, courtesy K.Y. Lo/NRAO/AUI)
![Page 29: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/29.jpg)
Sgr A West (“spiral”):
2 pc diameter,
∼ 60 M ionized gas, shaped by
tidal forces
(probably influence of mG B-field),
northern arm falls on center, east
and south arms rotate.
around Sgr A West: circumnuclear
disk of molecular gas, (r ∼ 2 pc).
total mass accretion rate onto
Sgr A∗:
∼ 3× 10−6 M yr−1
Sgr A (3.6 cm, courtesy K.Y. Lo/NRAO/AUI)
![Page 30: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/30.jpg)
I
EF
CO
DRI
L
A I
N
RDNXA
EA
ESII
C
M
LMV
A
AI
AD
R
E
L G
E
5–29
The Galactic Center 4
The Inner Parsec: Central Cluster, I
Center of Sgr A contains massive
and dense cluster
(> 106 M pc−3, compare solar
neighborhood: 0.1 M pc−3)
Spectroscopy: Stars are rich in
Helium, early type (=massive),
strong winds
(vWind ∼ 1000 km s−1).
![Page 31: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/31.jpg)
I
EF
CO
DRI
L
A I
N
RDNXA
EA
ESII
C
M
LMV
A
AI
AD
R
E
L G
E
5–30
The Galactic Center 5
The Inner Parsec: Central Cluster, II
Observations are difficult because
of astronomical seeing
(∼ 0.7′′=0.2 pc)
Gemini North/AURA
![Page 32: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/32.jpg)
I
EF
CO
DRI
L
A I
N
RDNXA
EA
ESII
C
M
LMV
A
AI
AD
R
E
L G
E
5–30
The Galactic Center 6
The Inner Parsec: Central Cluster, III
Observations are difficult because
of astronomical seeing
(∼ 0.7′′=0.2 pc)
. . . which can be corrected by
adaptive optics
=⇒ resolution: diffraction limit!
θ = 1.22 rad · λ/d ∼ 1 mas
(for d = 8 m, λ = 2.2 µm)
=⇒ 140 AU for gal. center!
Gemini North/AURA
![Page 33: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/33.jpg)
I
EF
CO
DRI
L
A I
N
RDNXA
EA
ESII
C
M
LMV
A
AI
AD
R
E
L G
E
5–31
The Galactic Center 7
The Inner Parsec: Central Cluster, IV
N
E
2.76’ / 6.6 pc
20" / 0.8 pc
VLT ISAAC K-Band (2.2 µm) (Genzel/Eckart)
![Page 34: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/34.jpg)
1994
Genzel/Eckart
![Page 35: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/35.jpg)
1996
Genzel/Eckart
![Page 36: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/36.jpg)
2000
Genzel/Eckart
![Page 37: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/37.jpg)
Genzel et al. (MPE)/Ghez et al. (UCLA): dynamical mass determination by
measuring the proper motion of ∼ 40 stars of the central cluster (Fig.: MPE
results 1991–2000).
![Page 38: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/38.jpg)
I
EF
CO
DRI
L
A I
N
RDNXA
EA
ESII
C
M
LMV
A
AI
AD
R
E
L G
E
5–36
The Galactic Center 12
The inner parsec: mass determination
Velocity dispersion in the
center
For r ≥ 0.057 pc: Keplerian
velocity profile (σv ∝ v−1/2),
influenced by cluster at
smaller distances
Eckart & Genzel, 1997, MNRAS, 284, 576
![Page 39: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/39.jpg)
I
EF
CO
DRI
L
A I
N
RDNXA
EA
ESII
C
M
LMV
A
AI
AD
R
E
L G
E
5–37
The Galactic Center 13
The inner parsec: mass determination
Model: point source plus
cluster with a velocity
dispersion of 50 km s−1 =⇒
central mass: 2.4× 106 M.
Eckart & Genzel, 1997, MNRAS, 284, 576
Evidence for a very massive compact object in the Galactic center =⇒
Black Hole?
![Page 40: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/40.jpg)
ESO, Oct 2002
![Page 41: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/41.jpg)
![Page 42: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/42.jpg)
I
EF
CO
DRI
L
A I
N
RDNXA
EA
ESII
C
M
LMV
A
AI
AD
R
E
L G
E
5–40
The Galactic Center 16
The inner parsec: mass determination
Ghez et al. (2003) ESO
![Page 43: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/43.jpg)
I
EF
CO
DRI
L
A I
N
RDNXA
EA
ESII
C
M
LMV
A
AI
AD
R
E
L G
E
5–40
The Galactic Center 17
The inner parsec: mass determination
Ghez et al. (2003) Schödel et al. (2002)
Mass determination: 3. Kepler
a = 5.5 light days
P = 15.2 years=⇒
P 2
a3=
4π2
G(m∗ + MBH)
![Page 44: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/44.jpg)
I
EF
CO
DRI
L
A I
N
RDNXA
EA
ESII
C
M
LMV
A
AI
AD
R
E
L G
E
5–40
The Galactic Center 18
The inner parsec: mass determination
Ghez et al. (2003) Schödel et al. (2002)
The center of the Galaxy harbors a black hole with
MBH = (3.7± 1.0)× 106 M
![Page 45: Center Galactic The - FAUpulsar.sternwarte.uni-erlangen.de/wilms/teach/intro2_0607/intro2chap6.pdfWilhelm Bessel (1784–1846): First determination of a stellar parallax reminder:](https://reader034.fdocuments.net/reader034/viewer/2022050718/5e1813fc971c9000ab074eac/html5/thumbnails/45.jpg)
I
EF
CO
DR
I
L
AI
N
RDNXAEA
ESI
I
C
M LMVA
AI
AD
R
E
LGE
6–1
Gal
axie
s:C
lass
ifica
tion