cv structure formation in tidal tails john e. hibbard nraojhibbard/iau217/iau217hibbard.pdf ·...
TRANSCRIPT
Stru
ctu
re F
orm
atio
n
Stru
ctu
re F
orm
atio
n
in T
idal
Tai
lsin
Tid
al T
ails
John
E. H
ibba
rd
John
E. H
ibba
rd
NRAO
NRAO
-- CV
CV
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
A Ran
ge o
f Su
bstr
uctu
res
are
foun
d in
Tid
al T
ails
Out
stan
ding
Que
stio
ns:
On
wha
t sc
ales
(if
any)
are
the
se s
truc
ture
s bo
und?
Is t
his
an e
volu
tiona
ry s
eque
nce?
Are
thes
e “T
idal
Dw
arf
Gal
axie
s” (
TDG
s) r
obus
t en
titie
s?
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
The
Occ
urre
nce
of Y
oung
Sta
rs w
ithin
Tid
al
The
Occ
urre
nce
of Y
oung
Sta
rs w
ithin
Tid
al
Deb
ris h
as b
een
Not
ed f
or S
ome
Tim
eD
ebris
has
bee
n N
oted
for
Som
e Ti
me
You
ng S
tars
Dw
arf
Re
Re --
disc
over
ed
disc
over
ed
in t
he e
arly
in
the
ear
ly
1900
’s19
00’s
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
TDG
“Rog
ues
TDG
“Rog
ues
Gal
lery
”G
alle
ry”
Arp
245:
Duc
et a
l. 20
00AM
135
3-27
2: W
eilb
ache
ret
al.
2000
Igle
sias
-Par
amo
& V
ilche
z20
01N
GC3
860:
Sak
ai e
t al
. 200
2“T
adpo
le”:
Tra
n et
al.
2002
See
also
the
fol
low
ing
post
ers:
Lope
z-Sa
nche
z et
al.,
#27
5O
ster
loo
et a
l., #
284
Tem
porin
et a
l., #
315
Van
Drie
let
al.,
#32
4
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
••Bu
t m
ore
met
al
But
mor
e m
etal
ric
hric
h
Duc
, 199
5, P
hD T
hesi
s Uni
v. P
aris
Wei
lbac
here
t al.
2003
Prop
ertie
s Pr
oper
ties
sim
ilar
to o
ther
si
mila
r to
oth
er
dwar
fs…
dwar
fs…
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Form
atio
n of
Sel
fFo
rmat
ion
of S
elf --
grav
itatin
g Co
nden
satio
ns w
ithin
gr
avita
ting
Cond
ensa
tions
with
in
Tida
l Deb
ris s
uppo
rted
by
Theo
retic
al W
ork
Tida
l Deb
ris s
uppo
rted
by
Theo
retic
al W
ork
••Ba
rnes
& H
ernq
uist
, 199
2,
Barn
es &
Her
nqui
st, 1
992,
N
atur
e: Sw
ing
ampl
ifica
tion
of
Nat
ure:
Sw
ing
ampl
ifica
tion
of
stat
istic
al n
oise
due
to
Nst
atis
tical
noi
se d
ue t
o N
-- bod
y bo
dy
natu
re o
f si
mul
atio
nna
ture
of
sim
ulat
ion
••Po
stul
ate
that
rea
l dis
ks m
ight
Po
stul
ate
that
rea
l dis
ks m
ight
ha
ve s
imila
r “n
oise
” (s
tar
have
sim
ilar
“noi
se”
(sta
r cl
uste
rs, G
MCs
)cl
uste
rs, G
MCs
)
••Cl
umps
for
m p
rimar
ily f
rom
dis
k Cl
umps
for
m p
rimar
ily f
rom
dis
k m
ater
ial.
Very
litt
le d
ark
mat
ter
mat
eria
l. Ve
ry li
ttle
dar
k m
atte
r
••La
rges
t cl
umps
can
be
gas
rich,
La
rges
t cl
umps
can
be
gas
rich,
bu
t sm
alle
st a
re g
as p
oor
but
smal
lest
are
gas
poo
r (T(T
gas
gas~
10~
1044
K)K)Ba
rnes
&
Barn
es &
Her
nqui
stH
ernq
uist
, 199
2, N
atur
e, 3
60, 7
15, 1
992,
Nat
ure,
360
, 715
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
From
Mih
os, 2
001,
ApJ
, 550
, 94
Form
atio
n of
Sel
fFo
rmat
ion
of S
elf --
grav
itatin
g Co
nden
satio
ns w
ithin
gr
avita
ting
Cond
ensa
tions
with
in
Tida
l Deb
ris s
uppo
rted
by
Theo
retic
al W
ork
Tida
l Deb
ris s
uppo
rted
by
Theo
retic
al W
ork
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
From
Bar
nes,
2003
, in
prep
arat
ion
Form
atio
n of
Sel
fFo
rmat
ion
of S
elf --
grav
itatin
g Co
nden
satio
ns w
ithin
gr
avita
ting
Cond
ensa
tions
with
in
Tida
l Deb
ris s
uppo
rted
by
Theo
retic
al W
ork
Tida
l Deb
ris s
uppo
rted
by
Theo
retic
al W
ork
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
From
Bar
nes,
2003
, in
prep
arat
ion
Form
atio
n of
Sel
fFo
rmat
ion
of S
elf --
grav
itatin
g Co
nden
satio
ns w
ithin
gr
avita
ting
Cond
ensa
tions
with
in
Tida
l Deb
ris s
uppo
rted
by
Theo
retic
al W
ork
Tida
l Deb
ris s
uppo
rted
by
Theo
retic
al W
ork
••In
crea
sed
Jean
s m
ass
in
Incr
ease
d Je
ans
mas
s in
tid
ally
agi
tate
d di
sktid
ally
agi
tate
d di
sk••
Dis
pers
ion
incr
ease
d, s
o D
ispe
rsio
n in
crea
sed,
so
inte
rnal
ene
rgy
is
inte
rnal
ene
rgy
is
incr
ease
d, r
equi
ring
larg
er
incr
ease
d, r
equi
ring
larg
er
mas
s to
bin
d it
mas
s to
bin
d it
••H
owev
er:
Jean
s m
ass
is
How
ever
: Je
ans
mas
s is
m
inim
um m
ass
that
may
m
inim
um m
ass
that
may
co
llaps
e; d
oesn
’t sa
y th
at
colla
pse;
doe
sn’t
say
that
th
ere
will
be
mas
s th
ere
will
be
mas
s co
nden
satio
ns t
hat
larg
e.
cond
ensa
tions
tha
t la
rge.
Elm
egre
en, K
aufm
an &
Th
omas
son,
199
3, A
pJ:
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
It is
com
mon
to
call
any
enha
ncem
ent
a TD
G o
r TD
G c
andi
date
. Th
e pr
esum
ptio
n is
tha
t th
is r
epre
sent
s an
evo
lutio
nary
seq
uenc
e
Form
…G
row
…Ej
ecte
d…
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Que
stio
ns t
o be
add
ress
ed:
Que
stio
ns t
o be
add
ress
ed:
••Ar
e th
ere
boun
d ga
seou
s pr
ecur
sors
to
Are
ther
e bo
und
gase
ous
prec
urso
rs t
o op
tical
con
dens
atio
ns?
optic
al c
onde
nsat
ions
?••
Are
Are
TDG
sTD
Gs
boun
d by
bar
yons
alo
ne?
boun
d by
bar
yons
alo
ne?
••Ca
n th
e ph
ysic
al p
rope
rtie
s of
tid
al
Can
the
phys
ical
pro
pert
ies
of t
idal
su
bstr
uctu
res
be a
ccur
atel
y de
rived
?su
bstr
uctu
res
be a
ccur
atel
y de
rived
?••
Do
Supe
r St
ar C
lust
ers
(SSC
) oc
cur
with
in
Do
Supe
r St
ar C
lust
ers
(SSC
) oc
cur
with
in
tidal
tai
ls?
tidal
tai
ls?
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Und
er m
any
TDG
evo
lutio
nary
sce
nario
s, o
ptic
al
Und
er m
any
TDG
evo
lutio
nary
sce
nario
s, o
ptic
al
TDG
sTD
Gs
shou
ld h
ave
gase
ous
prec
urso
rssh
ould
hav
e ga
seou
s pr
ecur
sors
••U
se d
istr
ibut
ion
and
Use
dis
trib
utio
n an
d ki
nem
atic
s of
ki
nem
atic
s of
m
oder
ate
reso
lutio
n m
oder
ate
reso
lutio
n H
I ob
serv
atio
ns t
o H
I ob
serv
atio
ns t
o es
timat
e dy
nam
ical
es
timat
e dy
nam
ical
na
ture
of
gase
ous
natu
re o
f ga
seou
s su
bstr
uctu
re
subs
truc
ture
VLA
obse
rvat
ions
of
NG
C 40
38/9
: H
ibba
rd, B
arne
s, v
an d
erH
ulst
&
Ric
h, 2
001
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
HI
obse
rvat
ions
rev
eal a
wea
lth o
f st
ruct
ure
with
in t
he t
ails
. H
I ob
serv
atio
ns r
evea
l a w
ealth
of
stru
ctur
e w
ithin
the
tai
ls.
(res
olut
ion
~10
"(r
esol
utio
n ~
10" --
20",
20
", ∆∆
vv =5.
2 km
/s)
=5.
2 km
/s)
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Iden
tifie
d cl
umps
in t
ails
with
con
tras
t of
2 f
rom
Id
entif
ied
clum
ps in
tai
ls w
ith c
ontr
ast
of 2
fro
m
surr
ound
ing
mat
eria
l, an
d w
ith S
/N>
6su
rrou
ndin
g m
ater
ial,
and
with
S/N
>6
Also
Ide
ntifi
ed a
n eq
ual n
umbe
r of
"Al
so I
dent
ified
an
equa
l num
ber
of "
inte
rclu
mp
inte
rclu
mp "
reg
ions
" re
gion
s
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Clum
ps d
o no
t di
stin
guis
h th
emse
lves
fro
m
Clum
ps d
o no
t di
stin
guis
h th
emse
lves
fro
m
inte
rclu
mp
inte
rclu
mp
regi
on in
ter
ms
of o
ptic
al o
r H
I pr
oper
ties
regi
on in
ter
ms
of o
ptic
al o
r H
I pr
oper
ties
Inte
rclu
mp
Reg
ion
sIn
terc
lum
pR
egio
ns
Sout
her
nTa
ilSo
uth
ern
Tail
Clu
mps
Clu
mps
log
NH
Iσ H
I
µ B(B
-R)
Clu
mps
Clu
mps
Inte
rclu
mp
Reg
ion
s
Sout
her
nTa
il
Inte
rclu
mp
Reg
ion
s
Sout
her
nTa
il
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
MM**/
L/LBB=
5
=5
ex
p SF
H, 1
0 ex
p SF
H, 1
0 G
yrG
yr
••2T
=
2T =
--UU
33 σσΗ
ΙΗ
Ι2 2 =
G
= G
MMvi
rvi
r/(
aR/(
aR1/
21/
2) )
MMvi
rvi
r=
1.9
1x10
= 1
.91x
1066
σσ ΗΙ
ΗΙ2 2
RR1/
21/
2
••MM
gas
gas=
1.36
M=
1.36
MH
IH
I
••MM
star
sst
ars=
(M=
(M**/
L/LBB)
* L
) *
L BB
••fil
led
sym
bols
=
fille
d sy
mbo
ls =
fo
regr
ound
&
fore
grou
nd &
ba
ckgr
ound
sub
trac
tion
back
grou
nd s
ubtr
actio
n
MM**/
L/LBB=
0 =
0
MM**/
L/LBB=
2
=2
cons
t SF
H, 1
0 co
nst
SFH
, 10
Gyr
Gyr
Dyn
amic
al A
naly
sis:
Is
ther
e en
ough
mas
s D
ynam
ical
Ana
lysi
s: I
s th
ere
enou
gh m
ass
in g
as a
nd s
tars
to
mak
e cl
umps
bou
nd?
in g
as a
nd s
tars
to
mak
e cl
umps
bou
nd?
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Que
stio
ns t
o be
add
ress
ed:
Que
stio
ns t
o be
add
ress
ed:
••Ar
e th
ere
boun
d ga
seou
s pr
ecur
sors
to
Are
ther
e bo
und
gase
ous
prec
urso
rs t
o op
tical
con
dens
atio
ns?
optic
al c
onde
nsat
ions
?••
Are
Are
TDG
sTD
Gs
boun
d by
bar
yons
alo
ne?
boun
d by
bar
yons
alo
ne?
••Ca
n th
e ph
ysic
al p
rope
rtie
s of
tid
al
Can
the
phys
ical
pro
pert
ies
of t
idal
su
bstr
uctu
res
be a
ccur
atel
y de
rived
?su
bstr
uctu
res
be a
ccur
atel
y de
rived
?••
Do
Supe
r St
ar C
lust
ers
(SSC
) oc
cur
with
in
Do
Supe
r St
ar C
lust
ers
(SSC
) oc
cur
with
in
tidal
tai
ls?
tidal
tai
ls?
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
NG
C 7
252,
NG
C 3
921:
Con
cent
ratio
n of
gas
, you
ng st
ars,
HII
re
gion
s coi
ncid
e w
ith in
crea
sed
HI v
eloc
ity w
idth
.
If b
ound
, the
n M
/L~
4-6;
M
vir/M
bary
ons~
2
Hib
bard
et
al. 1
994,
Hib
bard
& v
an G
orko
m19
96
See
also
: Te
mpo
rinet
al.
2003
(po
ster
#31
5)M
ende
s de
Oliv
eira
et
al.
2001
(M/L
~5-
17)
Expe
ct M
/L<
2 fo
r di
sk(e
spec
ially
in li
ght
of o
bser
ved
HII
re
gion
s)
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
For
reas
onab
le M
For
reas
onab
le M
**/L,
clu
mps
and
TD
G c
andi
date
s /L
, clu
mps
and
TD
G c
andi
date
s re
quire
sig
nific
ant
dark
mat
ter
to b
e se
lfre
quire
sig
nific
ant
dark
mat
ter
to b
e se
lf --gr
avita
ting
grav
itatin
g
Red
poi
nts
from
Bra
ine
et a
l. 20
01, A
&A,
378
, 51
Blue
poin
ts f
rom
Hib
bard
et
al.,
in p
repa
ratio
nX’
s =
clu
mps
in S
. tai
l of
NG
C 40
38
Bary
on d
omin
ated
Dar
k M
atte
r do
min
ated
Log
Log
(
Log (
)
)
••Th
e co
nden
satio
ns
The
cond
ensa
tions
th
ey p
oint
to
are
they
poi
nt t
o ar
e ve
ry d
ark
mat
ter
very
dar
k m
atte
r do
min
ated
do
min
ated
Mje
ans
Mje
ans/
MH
I(M
o)
2.8E
10
3
61.
2E10
12
6E09
11
6E09
15
6E09
16
5E09
11
4E08
2
3E10
21
2E10
8
4E09
40
Elm
egre
en, K
aufm
an &
Th
omas
son,
199
3, A
pJ:
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Rec
ent
Obs
erva
tions
sho
w d
rast
ic
Rec
ent
Obs
erva
tions
sho
w d
rast
ic
kine
mat
ical
gra
dien
ts a
cros
s ca
ndid
ates
kine
mat
ical
gra
dien
ts a
cros
s ca
ndid
ates
••O
ptic
al e
mis
sion
line
s (H
Opt
ical
em
issi
on li
nes
(Hαα
, , HH
ββ , [
OII
I])
, [O
III]
)••
Gra
dien
ts o
f 10
0’s
km/s
acr
oss
1G
radi
ents
of
100’
s km
/s a
cros
s 1 --
2 2 kp
ckp
c••
Not
all
appe
ar t
o be
a lo
catio
ns w
here
tai
l N
ot a
ll ap
pear
to
be a
loca
tions
whe
re t
ail
is b
endi
ng b
ack
alon
g lin
eis
ben
ding
bac
k al
ong
line --
ofof-- s
ight
sigh
t••
Infe
rred
dyn
amic
al m
asse
s up
to
10In
ferr
ed d
ynam
ical
mas
ses
up t
o 10
1010MM
oo
••Im
plie
s M
/LIm
plie
s M
/LBB
~ 1
00~
100
-- 200
M20
0 M
oo/L/L
oo
See
also
: Te
mpo
rinet
al,
Post
er #
315;
Lo
pez-
Sanc
hez
et a
l. Po
ster
#27
5
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Wei
lbac
her,
Duc
, Frit
ze-v
.Alv
ensl
eben
2003
, A&
A[OIII]
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
““ Den
tist
Chai
r”
Den
tist
Chai
r”
Gal
axy
Gal
axy
Wei
lbac
here
t al.
200
2, A
pJ
Vel
ociti
es
from
Hβ
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Que
stio
ns t
o be
add
ress
ed:
Que
stio
ns t
o be
add
ress
ed:
••Ar
e th
ere
boun
d ga
seou
s pr
ecur
sors
to
Are
ther
e bo
und
gase
ous
prec
urso
rs t
o op
tical
con
dens
atio
ns?
optic
al c
onde
nsat
ions
?••
Are
Are
TDG
sTD
Gs
boun
d by
bar
yons
alo
ne?
boun
d by
bar
yons
alo
ne?
••Ca
n th
e ph
ysic
al p
rope
rtie
s of
tid
al
Can
the
phys
ical
pro
pert
ies
of t
idal
su
bstr
uctu
res
be a
ccur
atel
y de
rived
?su
bstr
uctu
res
be a
ccur
atel
y de
rived
?••
Do
Supe
r St
ar C
lust
ers
(SSC
) oc
cur
with
in
Do
Supe
r St
ar C
lust
ers
(SSC
) oc
cur
with
in
tidal
tai
ls?
tidal
tai
ls?
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Hig
h re
solu
tion
NH
igh
reso
lutio
n N
-- bod
y m
odel
of
“The
Mic
e”bo
dy m
odel
of
“The
Mic
e”
••Bu
lge
Bulg
e --di
skdi
sk-- H
alo
Hal
o pr
ogen
itors
(Ba
rnes
pr
ogen
itors
(Ba
rnes
(1
988,
199
6)(1
988,
199
6)••
MMda
rkda
rk/M/M
lum
lum=
4=
4
••1E
6 pa
rtic
les
1E6
part
icle
s––
64k
per
bulg
e64
k pe
r bu
lge
––20
0k p
er d
isk
200k
per
dis
k––
300k
per
hal
o30
0k p
er h
alo
Barn
es &
Hib
bard
, in
prep
arat
ion
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Fit
HI,
CO
, Fi
t H
I, C
O,
Hal
pha
Hal
pha
mor
phol
ogy
and
mor
phol
ogy
and
kine
mat
ics
kine
mat
ics
HI:
Hib
bard
& v
an G
orko
m19
96;
CO:
Yun
& H
ibba
rd 2
001;
Hal
pha:
Mih
oset
al.
1993
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Hig
h re
solu
tion
allo
ws
sign
ifica
nt
Hig
h re
solu
tion
allo
ws
sign
ifica
nt
num
ber
of p
artic
les
per
TDG
num
ber
of p
artic
les
per
TDG
••NN
max
max
~ 1
100
~ 1
100
••Al
low
s ac
cura
te
Allo
ws
accu
rate
de
term
inat
ion
of
dete
rmin
atio
n of
ph
ysic
al p
rope
rtie
s ph
ysic
al p
rope
rtie
s (h
alf
(hal
f --lig
ht r
adiu
s,
light
rad
ius,
ve
loci
ty d
ispe
rsio
n,
velo
city
dis
pers
ion,
vi
rial
viria
l mas
s)m
ass)
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Iden
tify
64 c
lum
ps a
t la
te t
imes
(~
300
Iden
tify
64 c
lum
ps a
t la
te t
imes
(~
300
Myr
Myr
from
tod
ay)
with
E/m
<0,
T/U
<fr
om t
oday
) w
ith E
/m<
0, T
/U<
-- 0.50.5
••Re
stric
t th
is t
o 18
with
N>
50, w
ell d
efin
ed p
eak
Rest
rict
this
to
18 w
ith N
>50
, wel
l def
ined
pea
k••
Part
icle
s ex
trac
ted
from
tai
l & m
easu
re h
alf
Part
icle
s ex
trac
ted
from
tai
l & m
easu
re h
alf --
light
rad
ius
and
velo
city
dis
pers
ion
light
rad
ius
and
velo
city
dis
pers
ion
••Ph
ysic
al s
cale
s se
t by
mat
ch t
o ob
serv
atio
nsPh
ysic
al s
cale
s se
t by
mat
ch t
o ob
serv
atio
ns
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Do
boun
d re
gion
s sh
ow d
istin
ct
Do
boun
d re
gion
s sh
ow d
istin
ct
obse
rvat
iona
l sig
natu
res?
obse
rvat
iona
l sig
natu
res?
••So
met
imes
…So
met
imes
…––
Mos
t cl
umps
cor
resp
ond
to
Mos
t cl
umps
cor
resp
ond
to
dens
ity e
nhan
cem
ents
dens
ity e
nhan
cem
ents
––La
rger
clu
mps
vis
ible
hav
e La
rger
clu
mps
vis
ible
hav
e en
hanc
ed v
eloc
ity
enha
nced
vel
ocity
di
sper
sion
disp
ersi
on••
But…
But…
––N
ot a
ll cl
umps
are
obv
ious
N
ot a
ll cl
umps
are
obv
ious
en
hanc
emen
tsen
hanc
emen
ts––
Not
all
enha
ncem
ents
are
N
ot a
ll en
hanc
emen
ts a
re
boun
d cl
umps
boun
d cl
umps
––M
ost
clum
ps h
ave
Mos
t cl
umps
hav
e di
sper
sion
~
disp
ersi
on ~
inte
rclu
mp
inte
rclu
mp
mat
eria
l, so
are
not
dis
tinct
mat
eria
l, so
are
not
dis
tinct
––Pr
ojec
tion
effe
cts
can
wip
e Pr
ojec
tion
effe
cts
can
wip
e ou
t si
gnat
ures
out
sign
atur
es
Face
-on
Incl
ined
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Face
-on
Incl
ined
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Abili
ty t
o Ab
ility
to
reco
ver
true
re
cove
r tr
ue
phys
ical
ph
ysic
al
para
met
ers
para
met
ers
depe
nds
on
depe
nds
on
reso
lutio
n…re
solu
tion…
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
……an
d, m
ost
and,
mos
t im
port
antly
, im
port
antly
, on
vie
win
g on
vie
win
g an
gle
angl
e
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Abili
ty t
o de
rive
true
pro
pert
ies
Abili
ty t
o de
rive
true
pro
pert
ies
depe
nds
criti
cally
on
view
ing
angl
ede
pend
s cr
itica
lly o
n vi
ewin
g an
gle
Face
-on
Incl
ined
Mto
tal=
5E9
Mo
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
VLA
B-ar
ray
HI
Map
ping
of
NG
C 40
38/9
FWH
M
= 4
.5”x
4.0”
= 4
15x3
70pc
Tspi
n=
120
KN
HI,
peak
= 3
x102
1cm
-2
MH
I
= 1
x107
Mo
σσ HI
HI
= 5
km
/sR
half
= 5
00 p
cM
vir
= 3
x107
Mo
Som
e re
gion
s m
ay b
e bo
und,
but
on
smal
ler
scal
es
Com
pare
C+
D A
rray
:Ts
pin
=
40 K
NH
I,pe
ak=
1.4
x102
1cm
-2
MH
I
=
2.4
x108
Mo
σσ HI
HI
= 1
3 km
/sR
half
= 3
.2 k
pcM
vir
= 1
x109
Mo
Hib
bard
& H
igdo
n, in
pre
para
tion
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Tida
l Sub
stru
ctur
e Co
nclu
sion
s:Ti
dal S
ubst
ruct
ure
Conc
lusi
ons:
••M
ost
cond
ensa
tions
do
not
Mos
t co
nden
satio
ns d
o no
t ha
ve e
noug
h lu
min
ous
have
eno
ugh
lum
inou
s m
atte
r to
be
self
mat
ter
to b
e se
lf --gr
avita
ting.
gr
avita
ting.
••
If t
hey
ARE
self
If t
hey
ARE
self --
grav
itatin
g,
grav
itatin
g,
they
mus
t be
dar
k m
atte
r th
ey m
ust
be d
ark
mat
ter
dom
inat
eddo
min
ated
••Rec
ent
kine
mat
ical
Rec
ent
kine
mat
ical
si
gnat
ures
ver
y in
trig
uing
si
gnat
ures
ver
y in
trig
uing
––re
quire
larg
e am
ount
s of
re
quire
larg
e am
ount
s of
da
rk m
atte
r da
rk m
atte
r
••D
eriv
atio
n of
dyn
amic
al
Der
ivat
ion
of d
ynam
ical
pr
oper
ties
conf
used
by
prop
ertie
s co
nfus
ed b
y ad
jace
nt t
idal
mat
eria
l, ad
jace
nt t
idal
mat
eria
l, re
solu
tion,
and
esp
ecia
lly
reso
lutio
n, a
nd e
spec
ially
pr
ojec
tion
effe
cts
proj
ectio
n ef
fect
s ••
Man
y TD
G c
andi
date
s m
ay
Man
y TD
G c
andi
date
s m
ay
be c
olle
ctio
n of
sm
alle
r be
col
lect
ion
of s
mal
ler
boun
d un
its. I
n th
is c
ase,
bo
und
units
. In
this
cas
e,
mas
s sc
ale
may
be
mor
e m
ass
scal
e m
ay b
e m
ore
appr
opria
te t
o ap
prop
riate
to
dSph
dSph
than
to
than
to
dIrr
dIrr
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Tida
l Sub
stru
ctur
e Co
nclu
sion
s:Ti
dal S
ubst
ruct
ure
Conc
lusi
ons:
••W
ould
be
very
rea
ssur
ing
to f
ind
evid
ence
of
Wou
ld b
e ve
ry r
eass
urin
g to
fin
d ev
iden
ce o
f ki
nem
atic
ally
kine
mat
ical
lydi
stin
ct T
DG
can
dida
te in
fac
edi
stin
ct T
DG
can
dida
te in
fac
e --on
sys
tem
on s
yste
m
Arp
107
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Que
stio
ns t
o be
add
ress
ed:
Que
stio
ns t
o be
add
ress
ed:
••Ar
e th
ere
boun
d ga
seou
s pr
ecur
sors
to
Are
ther
e bo
und
gase
ous
prec
urso
rs t
o op
tical
con
dens
atio
ns?
optic
al c
onde
nsat
ions
?••
Are
Are
TDG
sTD
Gs
boun
d by
bar
yons
alo
ne?
boun
d by
bar
yons
alo
ne?
••Ca
n th
e ph
ysic
al p
rope
rtie
s of
tid
al
Can
the
phys
ical
pro
pert
ies
of t
idal
su
bstr
uctu
res
be a
ccur
atel
y de
rived
?su
bstr
uctu
res
be a
ccur
atel
y de
rived
?••
Do
Supe
r St
ar C
lust
ers
(SSC
) oc
cur
with
in
Do
Supe
r St
ar C
lust
ers
(SSC
) oc
cur
with
in
tidal
tai
ls?
tidal
tai
ls?
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
HST
stu
dy o
f O
ptic
al
Subs
truc
ture
in
Tida
l Tai
ls
N40
38/9
, N32
56
N39
21, N
7252
WFC
VI
13 o
rbits
P.I.
Cha
rlton
Knie
rman
net
al.
AJ, s
ubm
itted
N40
38 T
DG
W
FC U
BVI
11 o
rbits
P.I.
Hib
bard
Savi
ane
et a
l.AJ
, sub
mitt
ed
Afte
r co
rrec
ting
for
back
grou
nd c
onta
min
atio
n,
Afte
r co
rrec
ting
for
back
grou
nd c
onta
min
atio
n,
only
one
tai
l sho
ws
sign
ifica
nt p
opul
atio
n of
on
ly o
ne t
ail s
how
s si
gnifi
cant
pop
ulat
ion
of
com
pact
sou
rces
co
mpa
ct s
ourc
es
Knie
rman
et a
l., A
J, s
ubm
itted
NG
C 40
38 S
NG
C 32
56 W
Des
pite
the
lack
of
a si
gnifi
cant
tid
al p
opul
atio
n of
sta
r cl
ust
Des
pite
the
lack
of
a si
gnifi
cant
tid
al p
opul
atio
n of
sta
r cl
ust e
rs,
ers,
th
ere
are
conc
entr
atio
ns o
f st
ar c
lust
ers
asso
ciat
ed w
ith t
he T
Dth
ere
are
conc
entr
atio
ns o
f st
ar c
lust
ers
asso
ciat
ed w
ith t
he T
DG
G
ca
ndid
ates
in b
oth
NG
C 72
52 a
nd N
GC
4038
cand
idat
es in
bot
h N
GC
7252
and
NG
C 40
38
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
No
sim
ilar
No
sim
ilar
popu
latio
n in
po
pula
tion
in
CMD
eith
er o
n CM
D e
ither
on
or o
ff t
he t
ail
or o
ff t
he t
ail
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
NG
C 40
38 T
DG
Can
dida
te.
NG
C 40
38 T
DG
Can
dida
te.
HST
: Sa
vian
e, H
ibba
rd &
Ric
h, A
J, s
ubm
itted
HI:
Hib
bard
, van
der
Hul
st, B
arne
s &
Ric
h, 2
001
N E HST
WFP
C2
HST
WFP
C2 T
ruec
olor
True
colo
r(V
,V+
I,I)
(V
,V+
I,I)
w
ith H
I co
ntou
rsw
ith H
I co
ntou
rs
Star
Clu
ster
con
cent
ratio
n in
TD
G C
andi
date
St
ar C
lust
er c
once
ntra
tion
in T
DG
Can
dida
te
in t
he S
tai
l of
NG
C 40
38in
the
S t
ail o
f N
GC
4038
Loca
tion
of T
ail S
tar C
lust
ers
Savi
ane,
Hib
bard
& R
ich,
AJ,
subm
itted
Tail
star
clu
ster
s com
pare
d to
SS
Csi
n in
ner r
egio
ns: s
mal
ler,
mor
e irr
egul
ar
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Tida
l Sub
stru
ctur
e Co
nclu
sion
s:Ti
dal S
ubst
ruct
ure
Conc
lusi
ons:
••Br
ight
sta
r cl
uste
rs
Brig
ht s
tar
clus
ters
so
met
imes
, but
not
alw
ays,
so
met
imes
, but
not
alw
ays,
fo
und
in t
ails
foun
d in
tai
ls••
Star
clu
ster
s “o
ften
” St
ar c
lust
ers
“oft
en”
conc
entr
ated
in v
icin
ity o
f co
ncen
trat
ed in
vic
inity
of
TDG
can
dida
tes
TDG
can
dida
tes
Stru
ctur
e Fo
rmat
ion
in T
idal
Tai
lsJ.
Hib
bard
, NRAO
IA
U S
217
Jul
y 17
200
3
Fate
of
clum
ps?
Fate
of
clum
ps?
••M
ost
tidal
mat
eria
l rem
ains
bou
nd t
o M
ost
tidal
mat
eria
l rem
ains
bou
nd t
o re
mna
nt, s
trea
ms
back
in o
n sc
ales
re
mna
nt, s
trea
ms
back
in o
n sc
ales
of
of
Gyr
Gyr
••Bo
und
units
will
be
tidal
ly h
eate
d Bo
und
units
will
be
tidal
ly h
eate
d an
d st
rippe
d do
wn
to a
few
% o
f an
d st
rippe
d do
wn
to a
few
% o
f or
igin
al m
ass
orig
inal
mas
s
••In
clu
ster
env
ironm
ent,
out
er
In c
lust
er e
nviro
nmen
t, o
uter
re
gion
s w
ill b
e st
rippe
dre
gion
s w
ill b
e st
rippe
d
••Fa
te o
f m
ore
ener
getic
end
s of
tai
ls
Fate
of
mor
e en
erge
tic e
nds
of t
ails
de
pend
s on
dar
k m
atte
r co
nten
tde
pend
s on
dar
k m
atte
r co
nten
t
Barn
es &
Ba
rnes
& H
ernq
uist
Her
nqui
st, 1
992,
Nat
ure,
360
, 715
, 199
2, N
atur
e, 3
60, 7
15