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Notes for object Holmberg II

24 note(s) found in NED.


1. 2011AJ....141...23B
Re:Holmberg II
A.4. Holmberg II
Holmberg II is a gas-rich dwarf galaxy located at a distance
of 3.4 Mpc and is a member of the M 81 group of galaxies
as well. An HI hole analysis was carried out by Puche et al.
(1992) in which they found 51 holes across the entire face of
this galaxy. We detected 39 holes in Holmberg II the majority
of which were also detected by Puche et al. (1992), all with
very good agreement with respect to the position and size of
the holes. The difference in the number of holes detected is
due to our strict criteria of what constitutes a genuine hole
as well as to the fact that several holes in our catalog were
classified as a superposition of two (or more) holes from the
Puche et al. catalog. As panel (C4) in the online version of
Figure 30 illustrates, these holes dominate the HI distribution
of Holmberg II. In addition, several supershells were detected,
the largest one (no. 17) being over 2 kpc, one of the largest
and oldest (~150 Myr) across the entire sample of holes. Note
that hole no. 37 is probably a superposition of two or more
holes.

2. 2009AJ....138.1203M
Re:DDO 050
A.4. DDO 50 DDO 50 was the second most distant galaxy in our survey at 3.4 Mpc,
but we were still able to define 169 regions, 139 of which made it into the
final data set. Had this galaxy been located as close as WLM, from the number of
massive regions we see now and our experiments with WLM images, we might expect
to have identified 520 regions instead of only 169. Cluster formation in this
galaxy appears to have been relatively constant until about 9 Myr ago. However,
there is a small enhancement in the numbers of massive clusters 23-30 Myr
compared to the period of time before that. The most-massive cluster we
identified is 1 * 10^5^ M_sun_.
Because H{alpha} extends nearly as far as star formation seen in the UV
(4.1' for H{alpha} and 5.1' for the UV), we found only 10 regions
beyond R_H{alpha}_. The outer regions sample the full distribution of masses
despite the small sample size, but they tend to be a little lower in mass on
average compared to those in the rest of the galaxy.

3. 2009A&A...503..409H
Re:Holmberg II
There is no convincingly detected polarized emission from Holmberg II. There is
possibly very faint (at/below about the 4{sigma} level) emission at the location
of the higher brightness features in the eastern part of the galaxy which, as
discussed by Braun et al. (2007), are associated with H{alpha}-emitting regions.
This possible emission is not seen in the map produced using only the 22 cm
data. However, to the southwest (visible in Fig. 4) is a classic double-lobed
radio source which is strongly polarized. The source is catalogued as 6C
B081222.3+704711. The morphology of the polarized emission mostly fills the
region of continuum emission, but with strong depolarization channels in the
northern lobe. The southern lobe is somewhat brighter in both polarized and
unpolarized emission. The polarized fraction is about 3-4% in the core, and
about 10-20% along the jet axis. There are localized regions of higher polarized
fraction, at about the 40% level, and even reaching as high as 50%. The magnetic
field orientation is parallel to the northern and southern lobes on their
western edges, but on the eastern edges is perpendicular to the lobes, where the
total continuum morphology also suggests a smooth decline toward the east.
Despite the fact that the two lobes have nearly equal integrated brightness in
P, they display RMs which follow the pattern noted above in Sect. 3.1 for a
larger degree of RM fluctuations to be seen toward the fainter, northern lobe.
Given the obvious depolarization channels, this difference is perhaps not too
surprising. In view of the 1.5 arcmin angular separation of the depolarization
channels in the northern lobe from the nuclear position, it would require either
a very extended dispersive halo of the host galaxy, a localized source of
significant rotation, or internal depolarization to account for both the RM
fluctuations and depolarization. Unfortunately no red-shift information is
available for this source, although the nucleus appears to be coincident with a
moderately bright, but uncatalogued Digital Sky Survey source. The most likely
Galactic foreground RM for this field seems to be about -10+/-2 rad m^-2^.

4. 2009A&A...493..871S
Re:UGC 04305
UGC 4305 has previously been found to have a violent interstellar medium (e.g.,
Puche et al. 1992). The observations presented here also show signs of holes,
shells, and small-scale kinematic irregularities, making an accurate
determination of the rotation curve difficult.

5. 2008MNRAS.390..466E
Re:UGC 04305
UGC 4305. The centre has been changed from Paper III, and is now more to the
East. It has been determined from a Two-Micron All-Sky Survey (2MASS) image in
the infrared. This centre still gives a fairly symmetric rotation curve. It
coincides approximately with the H I kinematical centre but absolutely not with
the optical centre of isophotes. The counter rotation seen in the rotation curve
of Paper III is not seen anymore in the new rotation curve due to the new
centre. However, peculiar motions are still seen in the velocity field near the
optical centre of isophotes. Depending on the centre chosen for kinematical
analysis, they can be interpreted as the non-regular motions or as a counter
rotation.

6. 2008MNRAS.385..553D
Re:Holmberg II
Holmberg II: The H{alpha} content of this irregular galaxy shows weak
rotation and a lack of spatial coverage, therefore no kinematical
parameters or rotation curve could be extracted. Besides, the neutral
gas appears compressed on the south-east with a large but faint
component extending on the opposite side, indicating ram pressure
stripping from the intergalactic medium (Bureau & Carignan 2002). The H
I velocity field displays a weak but clear rotating disc pattern. Like
most of the dwarfs (see e.g. Carignan & Purton 1998), there is more
luminous mass in H I than in stars, but contrary to most dwarfs where
dark matter dominates at nearly all radii, in Ho II, dark matter
dominates only in the outer parts of the galaxy like in massive spirals.

7. 2005ApJS..157...59L
Re:Holmberg II
PGC 23324 (Holmberg II) is a Magellanic irregular galaxy at a distance of 4.5
Mpc with numerous H II regions and blue stellar complexes. ULX1 (IXO 31) is an
extreme ULX with L_X_ = 28.4 * 10^39^ ergs s^-1^. It is located in an H II
complex that shows strong He II {+lambda}4686 that requires ionizing X-ray
emission of ~1 * 10^40^ ergs s^-1^, thus arguing against beaming of the X-ray
emission (PM2002). This region also exhibits flat-spectrum radio emission
indicative of a supernova remnant (Tongue & Westpfahl 1995).

8. 2004MNRAS.349..225G
Re:UGC 04305
4.6 UGC 4305 This dwarf magellanic galaxy, well known as HoII and member
of the M81 group, has a patchy crab-like morphology. The H{alpha}
emission is mainly located along the minor axis and on the southern side
of the galaxy along two arm-like structures. A nucleus can be seen on
the continuum map and has been chosen as the centre of rotation. The
radial velocity amplitude is rather faint (~=50 km s^-1^). The final
velocity field shows numerous granulations (see the coloured version on
our web site) and the dispersion of velocities is close to 40 km
s^-1^. Because of the non-symmetric distribution of the ionized gas, we
obtain few velocity points for the blueshifted side; the derived
rotation curve reaches a plateau of 40 km s^-1^ at about 70-arcsec
radius (we have adopted the inclination derived by Swaters 1999, because
of the faintness of the velocity gradient which does not allow us to
constrain the inclination). Between -18 and +10 arcsec, a
counter-rotation is observed on the rotation curve. This galaxy has been
already studied at radio wavelength by several authors (Swaters 1999;
Bureau & Carignan 2002; Swaters et al. 2002); our rotation curve is in
fairly good agreement with their H I curves but the internal slope is
clearly steeper (0.6 versus 0.2 and 0.4 km s^-1^ arcsec^-1^
respectively). The PA determined in optical is 194deg, versus 168deg in
radio for Bureau & Carignan (2002) and 172deg for Swaters (1999).

9. 2003A&A...411..391L
Re:KIG 0239
CIG 239 - Center undefined, fitted with a 25{sigma}- threshold on the
optical peak of the bright eastern feature.

10. 2002AJ....124..675C
Re:UGC 04305
HoII, large irregular galaxy.

11. 2002A&A...383..125K
Re:Holmberg II
Holmberg II = DDO 50 = UGC 4305. This irregular galaxy of the Magellanic
(Im) type with numerous bright HII regions and blue stellar complexes has
a size of 8' x 6'. From the brightest stars de Vaucouleurs (1978) and
Tikhonov et al. (1992) estimated its distance modulus to be 27.79 mag and
27.78 mag, respectively. Our photometry gives I(TRGB) = 23.66 +/- 0.13 mag,
and (m-M)_0_ = 27.65 mag.

12. 1999ApJ...519...89C
Re:Holmberg II
Ho II.-This dwarf Irr galaxy is a companion to M81. We found a
bright compact X-ray source approximately 2' to the east of the galaxy
center.

13. 1998AJ....116.2682C
Re:IRAS 08140+7052
Ho II, UGC 04305. The ROSAT sources lie on the brightest radio peak
(Condon 1987).

14. 1998A&AS..129...87B
Re:IRAS 08140+7052
IRAS 08140+7052:
Irregular galaxy H_O_ II with about 7 arcmin diameter, multi-component X-ray
emission. Classification grade 1 is given since all the emission originates
inside the galaxy despite the large offset between the IRAS FSC and the X-ray
centroid positions. The infrared luminosity may be larger than given by FSC/PSC.

15. 1998A&AS..129...87B
Re:IRAS 08140+7052
Irregular galaxy Ho II with about 7 arcmin diameter, multi-component X-ray
emission. Classification grade 1 is given since all the emission originates
inside the galaxy despite the large offset between the IRAS FSC and the X-ray
centroid positions. The infrared luminosity may be larger than given by FSC/PSC.

16. 1994CAG1..B...0000S
Re:Holmberg II
M81/NGC 2403 Group
Hubble Atlas, p. 39
ImIV-V
PH-1600-B
Nov 30/Dec 1, 1956
103aO + GG1
25 min
HoII was first identified by Holmberg
(1950) in his catalog and study of the
M81/NGC 2403 Group. The resolution into individual
stars is at the same bright level as in other members
of the Group, such as NGC 2403 (Sc; panel 273),
NGC 2366 (SBmIV-V; panel 327), and NGC 4236
(SBdIV; panels 324, S10).
Photometry of the brightest red and blue
stars has been done by Sandage and Tammann
(1974b) and by Hoessell and Danielson (1984).
The blue stars begin to resolve at about B = 19.7
in the photometry of Sandage and Tammann. The
brightest red supergiants begin to resolve at
about V = 20.2.
In the photometry of Hoessell and Danielson,
the brightest blue stars resolve at B = 17.8.
The identification of the brightest stars differs
between the two studies. Finding charts of the
individual stars are given in both. New
photometry is required (c. 1991) to remove this
important discrepancy.
HoII has a maximum "rotational velocity"
of 58 km/s, determined from the 21-cm line
profile (Huchtmeir, Seiradakis, and Materne
1981). Its heliocentric systemic velocity is
v_sun_ = 159 km/s. Correction to the centroid of
the Local Group gives v_o = 329 km/s, clearly
beyond the zero velocity surface of the Local
Group. HoII is, beyond doubt, in the near expansion
field (see Fig. 9 of Sandage 1986a) of the
very local Hubble flow.

17. 1993ApJS...86....5K
Re:HOLMBERG II
Holmberg II (VII Zw 223, Arp 268, DD0 50); Irr, BCDG.
Holmberg II is a blue compact dwarf galaxy described by Zwicky (1971) as
a large posteruptive blue irregular with compact core and many knots. It
is a resolved galaxy in the M 81-NGC 2403 group. With a distance of about
3 Mpc, it is one of the nearest condensations in the local supercluster
(Sandage & Tammann 1975). Despite its location in a group, Holmberg II
does not appear to be physically interacting (Davis & Seaquist 1983).
The UV emission of Holmberg II is dominated by a single giant H II
region, where intense star formation is taking place. Indeed, the
continuum of the UV spectrum is typical of an H II region (cf. Rosa et
al. 1984). The spectrum shows possible nebular emission of
C III] {lambda}1909. The galaxy-wide star formation rate is lower than
that typical of normal spiral galaxies and can be considered
approximately constant over a Hubble time (Hunter & Gallagher 1985).
Analysis of IRAS observations suggests that only a small amount of dust
is present in Holmberg II, so that little hidden star formation can be
present (Hunter et al. 1989a) -Like most dwarf irregulars, the
metallicity of Holmberg II is low compared to that of normal spiral
galaxies and is intermediate between the metallicity of the LMC and that
of the SMC (Hunter & Gallagher 1985).

18. 1976RC2...C...0000d
Re:[RC2] A0813+70
= Holmberg II (1958)
= DDO 50
= Arp 268
= VII Zw 223
In M81 Group.
Photograph:
Ap. J., 190, 525, 1974.
Ap. J., 191, 603, 1974.
Photometry: Brightest blue and red stars:
Ap. J., 191, 603, 1974.
HII Regions:
"Atlas and Catalogue", Univ. of Washington, Seattle, 1966.
Ap. J., 156, 847, 1969.
Ap. J., 190, 525, 1974.
Distance Modulus:
Ap. J., 190, 525, 1974.
HI 21cm:
Ap. J., 150, 8, 1967.
IAU Symp. No. 44, 12, 1972.
Radio Observations:
A.J., 78, 18, 1973.

19. 1973UGC...C...0000N
Re:UGC 04305
Arp 268, VII Zw 223, DDO 50
In Arp's class "galaxies with irregular clumps"
A0814 in RC1
Im (de Vaucouleurs), Ir I (Holmberg), Ir IV-V (DDO)
"Resolution of stars Note linear loop of emission regions" (Arp)
"Large post-eruptive blue irregular with compact core and many knots" (CGPG)

20. 1971CGPG..C...0000Z
Re:CGPG 0814.1+7052
VII Zw 223
Holmberg II
Large, post-eruptive blue irregular
with a compact core and many knots.
= +164 km/sec.
m(pg) = 11.3 [CGCG]

21. 1966AJ.....71..922v
Re:DDO 050
= Holm II.

22. 1964RC1...C...0000d
Re:[RC1] A0814
= Holmberg II (1958)
Bright middle. Very irregular. Well resolved. Low surface brightness.
In the M81 Group.
Photometry:
Medd. Lund II, 128, 1950.
Spectrum:
A.J., 61, 97, 1956.
HII Regions:
Zeit. fur Ap., 50, 168, 1960.
HI emission
Epstein, Harvard Thesis, 1962.

23. 1961Hubbl.B...0000S
Re:Holmberg II
Irr I
PH-48-S
Nov. 29/30, 1951
103aO + WG2
30 min
Enlarged 2.0X
This is one of the members of the M81 group. It was
discovered by E. Holmberg during his study of the M81
Group (Medd. Lund Obs., Ser. II, 128, 1950). Its membership
in the M81 Group was proved by N. U. Mayall's redshift
determination (A. J., 61, 97, 1956). The distance
modulus of the M81 Group is about (m-M) = 27.1. The
limiting magnitude of the plate from which this reproduction
is taken is about m(pg) = 23.0. Hence all resolved stars
shown over the face of Holmberg II are brighter than M(pg) = -4.1.
There are many HII regions in Holmberg II.

24. 1956AJ.....61...97H
Re:Holmberg II
HMS Note No. 045
Brightest emission patch approximately in center of system.
Pretty bright star 20 arcsec [south-east].
Nebula is a dwarf in the M81 Group described
by Holmberg, E.E. 1950, Medd. Lunds Astr. Obs., Ser. II, No. 128.
HMS Note No. 046
Row of three faint emission patches near [south-east] side of system.
Star 30 arcsec [north-west] of central patch (HMS Plate IVk).


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