Date and Time of the Query: 2019-05-26 T08:12:11 PDT
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Notes for object NGC 5471

5 note(s) found in NED.

1. 2004MNRAS.355..728F
Re:NGC 5471
NGC 5471. This is a massive giant H II region located in M101.
Mas-Hesse & Kunth (1991) found WR-He II{lambda}4686/ H{beta}= 0.02 and a
3.5-Myr burst. NGC 5471 seems to be dominated by a well-defined burst
of star formation. A broad He II emission line (FWHM ~ 2000 km s^-1^)
was detected in this region by Castaneda, Vilchez & Copetti (1990) and
was confirmed by Mas-Hesse & Kunth (1991). We find a low ratio WR/O =
0.04 for this galaxy.

2. 2004MNRAS.349..404J
Re:CXOU J140429.1+542353
6.7 XMM-7 This source is one considered by Wang (1999) to be a HNR
candidate. The ROSAT HRI source (H49) is positionally coincident within
1{sigma} error radius of the optical position of NGC 5471B, one of the
SNRs detected in NGC 5471 by Skillman (1985) in the radio and Chu &
Kennicutt (1986) in the optical. Wang (1999) found that the ROSAT PSPC
data was consistent with a Raymond-Smith thermal plasma with a
temperature of 0.29 keV and an X-ray luminosity of L_X_= 3 x 10^38^ erg
s^-1^ (0.5-2 keV). Using these characteristics, they employed the Sedov
solution to estimate the total thermal energy of the SNR to be ~10^52^
erg (if that is where the X-ray emission originates). This is 10 times
that expected from a typical supernova and so suggests that it could be
a HNR. No temporal variability was detected in the ROSAT data,
consistent with the hypernova scenario.
More recently, Chen et al. (2002) have studied NGC 5471B using Hubble
Space Telescope (HST) WFPC2 continuum band and emission lines image
together with echelle spectra for kinematic studies. They found three
[S II]-enhanced shells in NGC 5471, the brightest of which is NGC 5471B
with an expansion velocity of >=330 km s^-1^, a kinetic energy of 5 x
10^51^ erg and hence an explosion energy >10^52^ erg. The WFPC2 images
showed that it has a complex environment of many concentrations of stars
and that the shell itself encompasses two young OB associations. The
ROSAT HRI contours are centred on NGC 5471B on the HST images and the
authors conclude that the SNR within it was produced by a hypernova, as
a shell moving at that velocity is unmatched by any comparable shells in
other galaxies that have been produced by multiple supernovae.
This source is an off-axis detection in the short Chandra observation,
and hence has insufficient counts for spectral fitting or an accurate
determination of its position. The XMM-Newton spectrum shows that this
source is very soft. It is well fitted with both an absorbed cool BBODY
(T _in_= 0.14 keV, {chi}^2^_{nu}_ = 0.93) model with an unabsorbed
luminosity of L_X_= 5.2 x 10^38^ erg s^-1^ and a DISKBB (T _in_= 0.16
keV, {chi}^2^{nu} = 0.96) model with an unabsorbed luminosity of L_X_=
1.0 x 10^39^ erg s^-1^. This cool temperature classifies this source as a
luminous supersoft source (SSS), similar to those found in other
galaxies (e.g. Di Stefano et al. 2004). Although not shown in Table 2,
this source was also adequately fitted with an absorbed single MEKAL
plasma model (kT= 0.1 keV, {chi}^2^_{nu}_ = 1.2). Its light curve shows
no variability over the time-scale of the XMM-Newton observation,
although there is evidence of variability in the long-term light curve
(factor of ~2.5). The nature of this source therefore remains open to
debate. A reasonable MEKAL X-ray spectrum and a lack of variability are
still consistent with an interpretation as a HNR. However, the
similarity of its spectral form to other SSSs, suspected to be XRBs,
offers an alternative solution.

3. 1999A&AS..136...35S
Re:NGC 5471
NGC 5471 -- Rayo et al. (1982) find a weak He II {lambda}4686
feature in this HII region of M 101. No information on its width is
given. D'Odorico et al. (1983) detect unbroadened lines identified as
C III {lambda}4658 [Fe III] {lambda}4658, He II {lambda}4686,
He I + [Ar IV] {lambda}4711 and [Ar IV] {lambda}4740, whose origin is
likely nebular. Mas-Hesse & Kunth (1991, 1998) mention the presence of a
WR bump.

4. 1977A&AS...28....1V
Re:VV 394
Plate 7 Ejection of the Twin Satellites
MCG +09-23-030; 15m.
Twin blue galaxies ejected or gemmated.

5. 1918PLicO..13....9C
Re:NGC 5471
A faint, indistinct spiral, slightly oval, 1' long; faint, almost stellar

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