|
RA : 06h to 08h |
SOUTHERN DOUBLES :
Δ30 Pup ,
Δ31 Pup ,
Δ32 Pup ,
ESO 122-11 & 11A Car , SOUTHERN VARIABLES : L2 Pup BRIGHT STARS :
OTHER DOUBLES and VARIABLES:
η Mon / 8 Mon / Σ900 &
(UGC3459 / PGC18964) , |
Eta (η) Monocerotis / 8 Mon /
Σ900 (06238+0436) is a very pretty white and
yellow pair in a starry field about
12oN of Beta Mon or
8oE of Betelgeuse. Since
discovered by F.G.W. Struve in 1831 the pair has been
slowly diminishing from 13.9" to 12.7", but the PA has
remained along 27o It was
uncertain if these stars were associated, as said in
“Astronomical Objects for Southern
Telescopes”; 2nd Edition (AOST2) by David Frew and
David Malin, but since the release of the Tycho / Hipparcos
data, the respective parallaxes are 25.39±1.02mas
and 41.09±10.14mas, combined with the RA and Dec
proper motions which are moving in opposite directions, it
is likely this is an optical double star. Σ900 is
also possibly joined to the open cluster Dolittle 23 (Do
23) whose 18' size holds about ten or eleven stars. As
AOST2 notes that 5'NW from 8 Mon is 9.7 mag star
T141:2248:1/ SAO113805/ PPM150409. Described as red, I saw
it as certainly orange or yellow-orange.
Owners of large Dobsonians may find in the same field the
14.7 mag, UGC3459 / PGC18964 (06240+4243), a Sc
spiral galaxy whose visually size measures 30"x22". It is
located 7.9' (PA 26o) which in
the same direction as 8 Mon. I would be interested if
anyone can see this object, as I can find no references in
sighting this galaxy.
Beta (β) Monocerotis / Σ919 (06288-0702) is a triple system. The closer "BC" pair magnitude 5.7 and 6.2 and is separated by 3.0"arcsec along PA 107o The "A" component is 5.1 magnitude and is some 10" away at PA 125o. Another 12th mag star, making the AD pair (BU 570), is 25"arcsec apart at PA 56o. Although invisible to amateur eyes, the companion of the "C" component was discovered as recently as 1988. Known as CHR 167 or "Cc"; the 5.6 and 6.1 mag stars are separated by 0.3" along PA 141o This makes Beta Mon possibly quintuplet. It is certain that the four stars are associated, but the "D" star is still undetermined. All stars are of B-spectral type, and are coloured light sapphire blue. This system is very attractive and not one to miss!
Δ30 (06297-5014) is
placed some 3.2oW of Tau (τ) Puppis, or
2.6'N and a little east of Carina's Canopus. The magnitudes
of the yellow and red-orange pair are 5.2 and 9.0,
separated by 11.7" at PA 313o.
Δ30 is a multiple star with both o the main
components show companions. Δ30 AB has an
orbital period of 53 years, and the equal 6.0 magnitude duo
can be seen in 20cm. Presently the AB system is separated by
0.8" (2003) whose PA is c.240o.
Another invisible component "ABb" is suspected.
Δ30 CD has a longer period of 102 years, however,
it is far more difficult to see. Presently the separation is
merely 0.5"arc sec, which will slowly increasing to 0.67"
by 2017. Both equal brightness stars are reddish. This "CD"
component should be visible due south in 30cm to 40cm with
care, requiring high magnification.
No doubt all the components of this the multiple system are
gravitationally connected, being likely a quintuplet system.
Δ31 (06387-4813) is another bright pair some 2.5oNE of 30 or 3oNW of Tau Puppis. Discovered by Dunlop in 1826, the components are 4.9 and 8.2 mag, separated by 13" at PA 320o. The pair reminds me very much of Δ51, with a small magnitude difference. I saw the pair also as orange and white. No change has been observed with the pair, so the true connection remains uncertain. The field is quite pretty.
Δ32 (06423-3824) lies near the western edge of Puppis, close to the Columba border, some 7oW then 1oS of Pi (π) Puppis (Δ43). Comparing the field to the other ones in this article, this field is quite spartan. Both stars are white and 6.5 and 8.0 amgnitude, respectively. Since the first observations in 1835 both the PA and separation have remained fixed at 276o and 8.0", respectively. A 7.5cm should see both stars with care, though 10.5cm would be much easier.
ESO 122-11 and
ESO 122-11A (06591-5908)
are two strongly interacting galaxies that can be found
32'W of Δ39. *(See Below) Both galaxies can be seen
in telescopes greater than about 20cm in dark and moonless
skies, but may be more difficult to see because of the
two nearby 6th magnitude star. Observers might like to
take the two stars out by move the telescope to the
southwest to eliminate from the field some of their
overwhelming light.
Both of the galaxy centres are separated by only 6.4"arc
seconds aligned NW to SE. Apparent sizes of these two
galaxies are given as 0.8'x0.4' and 1.0'x0.6' (48"x18"
and 60"x36"arc seconds) but I would expect you would see
only about half to one-third of this. Ie. 24"x9" and
30"x18"arc seconds.
Looking at the red image, you can clearly see the two
separate galaxies. Incidentally, the visual image is
merged because of the overexposure, but in allows you
to see the effects of the interaction with the tail
pointing to the west. These galaxies were taken by
Sue Triton on 13th January 1978 starting at 10h 44m PM
using the then UK Schmidt Camera atop of Siding Spring
- the Observatory of the Anglo Australian Observatory.
The Plate Number is J3870 and was made during the 7.5
minute exposure.
Do you see in the telescope two galaxies or just one
big nebulous mass? Can the cores be resolved or not?
What aperture is needed to do this?
Little is known about this interactive pair except the
radial velocities are 8 360 and 8 182
kms-1, respectively, giving
the mean distance of about 127 MPc (or about 415 million
light-years).
Note: By coincidence the pair DUN 7 in Horologium, four hours less in right ascension, has the interacting galaxies ESO 115-25 and ESO 115-25A near it. These are near the galaxy NGC 1096, which are all likely part of the same multiple-galaxy group. If you are interested in these “double galaxies”, it might be worth seeking out ESO115-25/25A on the same night.
HJ 3921 (07006-5824) lies in a fairly spartan field 50.8' (PA 336o) from Δ39. This faintish pair is listed as 8.3 and 11.5v magnitude, being separated by 5.8"arcsec along PA 272o. Since first measured by Innes in 1911, little has changed in the relative positions, and from the merger data available, it remains uncertain if the two stars are connected. HJ 3921 is easily seen in apertures as low as 7.5cm, but is nothing to write home about. If it were not so easy to find to the north of DUN 39 - I might not have even mentioned it.
Δ38 (07040-4337) is a triple system half-way between Sigma (σ) Puppis (Δ51) and Nu (ν) Puppis. Unlike most Dunlop pairs, the primary "AB" system is yellow and orange. Since discovery in 1836, the pair has continued to slowly widen by 0.8" and increased in angle by 5o. The separation now is c.21.3" at PA 125o, both stars being with 5.5 and 6.8 magnitude. It is likely that these two are physically associated as they have similar proper motions and parallaxes. Inspection of the field finds another bright yellow star preceding the main pair. This is the so-called Δ38 AC and wider than most, but since 1900, this star has reduced in separation from 184.8" down to 136.1" (1977), changing phenomenally by 0.63" per year! Also the PA has changed from 334o to 282o. I estimated the current positions as 115" at PA 250o (2001). This star is assuredly not physically associated with the AB system. In this case, the apparent motion is not this star, but actually due to the double's high proper motion and parallax. Using the Hipparcos data the average proper motion is -102.95"arcsec per century (1.72' per century) in RA and 392.71" per century (6.55' per century) in declination. This motion, however, is not the quickest in the heavens. 61 Cyg moves almost ten times faster. Observers might like to compare sketches over a number of years to physically see the motion for themselves. Distance to Δ38 AB is 15pc or 49±2ly.
Δ39 / DUN 39
(07033-5911) is a stunningly bright southern pair that
lies in Carina, some 1.5oE of
the mid-eastern Pictor border and
8.4oNE (exactly) (PA
315o) from the second brightest
star in the sky, Canopus. It can also be easily be found
some 3.3oNW (PA
35o) from the 3.2 magnitude Alpha
(α) Pictoris. The field itself contains a yellowish
6.0 magnitude star, some 22'NE (PA
310o) away that has another two
fainter companions (11th and 10th magnitude) in a slightly
crooked line. These latter stars will correctly identify
the field.
This is one of the very best of the Dunlop pairs discovered
from his home Parramatta in 1826. Listed also as 89 Argūs,
using the old Bode Numbering System that is similar in
nature to the Flamsteed Numbers, Dunlop gives the
magnitudes as “6,7” at 1828 co-ordinates of 07h
01m 13s and -58o 55'.
Δ39 has the naked eye combined magnitude of 5.1 whose
component magnitudes are each 5.50v and 6.52v (5.83V and
6.78V) magnitude. Separation is presently 1.4"arcsec along
PA 86o (1997). Since discovery,
the pair continues to become a more difficult as the
separation has decrease from 2.5 to 1.4 arcsec. Ie. Innes
measured the pair from South Africa in 1912, finding the
positions as 80.7o and
1.9"arcsec. Furthermore, the PA has continued to
progressively increase from 76o
to its present 86o (1997).
Using the available Hipparchos data, which I have assumed
is correct, finds that the pair's distance from the Sun is
147±7pc. (481±24ly.) - calculated from
the 6.77±0.34mas parallax. From this, the true
stellar separation would be around 216AU
(3.2x1010 km.) apart, each have
respective higher luminosities than the Sun of 118x and
46x with the absolute magnitudes of -0.35 and +0.67.
Association of the two components is almost certain, as
the proper motions are not too dissimilar, indicating the
stars are moving southwest toward PA
220o at some 14.84mas per year.
Visually I have seen this pair several times and each
time I saw the pair as bluish and yellowish. These
observations are contradicted by both Gould and E.J.
Hartung (See Below) who both call them yellowish.
Looking at the combined spectral class of B9IV and
the B-V of -0.125, it is hard to see how this pair could
be described as yellowish at all. Could the colour of
the other bright field star be influencing these observers?
Δ39 Descriptions
H.J. Hartung says in AOST1 (&2);
“[A] 7.5cm will readily resolve this bright pale yellow star. the components have shown a very slow approach and increase in angle since John Herschel's measures in 1836, and common proper motion indicates they are connected.”
Ross Gould ("Southern Astronomy"; Mar/ Apr 1994 pg.52-53) says of Δ39;
“A test for 8cm refractors, and not difficult with 10cm 'scopes. A pale yellow pair, of mags 6.0 and 7.1... In 1952 it was at 1.7", PA 82o.”
L2 Puppis (07135-4439) is commonly an example of a starting variable star for new observers. Some 3oSW of the star Sigma Puppis, finds. this deep red variable is always visible to the naked-eye. First discovered by Gould in 1872, it is known as a semi-irregular SRb variable, the mean period varies over c.141.9 days while the magnitudes ranging roughly from 3rd to 6th magnitude. It is not unusual for it to be brighter than this maximum on occasions. Ie. L2 Puppis has brightened once to 2.6 mag, or faded to 6.2. Its spectrum varies from M5 to M6 and shows unusual emission lines.
Δ43 / Pi (π) Puppis (07171-3706) is easy to find as it is the brightest of a small triangle of stars, some 7.4oS of Eta CMa, whose common name is Aludra. Pi Pup is separated by 69.2" at PA 213o, while the magnitudes are 2.7 and 8.0. Observations since 1826 has seen little changed in the positions. I saw the colours as deep orange and blue, making one-hell-of-a contrast, making it placed 3rd or 4th in my Top 10 of southern contrasting, just behind the magnificent x Velorum (Δ95)(10393-5536) in SE Vela. This field is just remarkably memorable.
JC 10 (07183-3644) was discovered by W.S. Jacob in 1846 appear in the next NW field. Both these blue stars are 5.1 and 8.7 magnitude and separated by 117" at PA 216o.
R CMa / R Canis Majoris,
(07195-1624) is located 8.4oW of
Sirius. It can be found 1.2°S of the 9th magnitude open
star cluster NGC 2360 containing about fifty stars between
9th and 11th magnitude. This eclipsing binary is listed as
semi-detached, suggesting that it is almost an EB system.
Magnitude variations change between 5.70 and 6.34, with the
period of 1.1359405 days where the primary minima varies by
0.64 magnitudes, while the secondary minima dips only 0.08
magnitudes. The period's length is suspected to vary
discontinuously.
Recent calculations place the mass of the system as 1.20
M
and 0.20 M (1989). W. Heintz in
Double Stars (1978) states that the masses of
the stars are respectively 1.80 M and 0.2 M, with the secondary that appears very
extended. It is likely that mass transference through the
Roche Lobe has occurred in the past, and may still be
continuing, with the primary being the youngest star. The
individual luminosities are 2.8 L and 0.1 L, with surface temperatures of 6 110K and 3
110K. True distance between the two stars, surface to
surface, is 3.5 million kilometres, with the respective
individual diameters of 2 million and 1.7 million
kilometres. Spectral classes are listed as F1V and K1VI
while distance is 27pc or 88 ly.
R 75 (07216-5521) is a triple
star containing a moderately faint close pair and another
wider faint component. Located in some 8oE of
Canopus, and roughly half-way between Canopus and the open
star cluster NGC 2516 at the bottom of the false cross,
this system is a faint portion of sky beyond the boundary
of the Milky Way. Since discovered by H.C. Russell in 1880,
there has been some motion in the main AB pair. When first
found the three stars were in a straight line, however the
movement of component ‘B’ has changed from PA
268o to PA 272o making it slightly
more bent than any straight line.
R 75 AB is the inner pair is visually given from
previous observers as 10.0 and 10.6 mag. with the Tycho
values being 10.43V and 11.28V magnitude AB is separated by
an unchanged 5.1"arcsec. The primary seems to be F3 III:
star.
R 75 AC is some 30.8"arc sec wide along PA
262o yet has hardly moved since discovery. R75 C
is given as 11.47 and 10.4v being a whole magnitude
different! When I last observed this pair in 1985, I saw
all the colours as both yellowish, however, this was a bit
harder to discern properly because of the faint magnitude
of the stars. It is possible that the inner pair are
associated, though there is some doubt about the wider
component. Although this triple won’t set the world
on fire its linear nature of the three stars is unusual.
Proper motions for the three stars are similar, so this is
likely a real system.
| Pair |
Sep. "arc sec |
P.A. (o) |
Mag. Components |
| R 75 AB | 5.1 | 272 | A=10.43 |
| R 75 AC | 30.8 | 262 | B=11.28 |
| R 75 BC | 25.8 | 260 | C=11.47 |
Δ47 / DAW 129 (07247-3149) is a wide yellow and white pair just inside the southeastern Canis Major border some 52' due west of Δ49. Both stars are 5.3 and 7.6 magnitude and are separated by 99.2" at PA 342o, and can be seen even in binoculars. Like Δ30, both components are again double. The brightest component, the "AB" system, was discovered by B.H.Dawson in 1922. Known as DAW 129, the pair is certainly difficult in apertures less than 25cm. At 5.3 and 11.0 magnitude, the stars and are separated by 1.9" along PA 309o. The fainter component in the "CD" system was discovered by W.H. van der Bos in 1929. The "D" component is 10.8, some 3.2 mag fainter than "C", and can be found about 1.0" along PA 205o. I found this second pair easier to separate than "AB", even though it is almost twice the separation. A 20cm using medium to high magnification should see each of the components. The connection of the CD is likely, though the distant pair AB-CD is presently uncertain. This pair will challenge some observers.
Δ49 (07289-3151) this magnificent pair lies near the southern Canis Major border. Both 6.4 and 7.2 magnitude stars are separated by 8.9" at PA 59o, and I saw both stars as blue and blue-white. Little has changed with this pair since Dunlop discovered Δ49 in 1836. The field is star-studded and the pair is simply dazzling!
Δ51 / Sigma (σ) Puppis (07292-4318) in my opinion is the best in this set of double stars. Located 20oS of M93, this bright pair is of 3.2 and 8.8 mag, whose components are separated by 22.2" along PA 74o. The pair is quite colourful, which I see as orange and white. Easily visible in 5cm, and little has changed in the positions since Dunlop discovered the pair in 1836.
HJ 4000 (07423-5840) is a challenge for apertures around 10cm to 15cm, and easy for anything above this. Located 44'NW R79, this 7.1 and 10.2 magnitude pair is easy to find as there is another 6.4 mag. blue star only 2.7' NNW (PA 150o). Close inspection finds that the other star is the double that takes some care to split. The problem is here is there is a moderate Δm of 2.6 mag. for the 1.4"arcsec separation. Colours are white but were uncertain because of the faintness of the comes. HJ 4000 is showing slow direct motion from Herschel’s angular measure in 1836 of 230o to its present 249o but the separation has remained fixed. As the proper motions in RA and Dec are almost fixed but both are at least very similar, so it is likely they are attached. Spectral Class for the primary is A1IV. Nice.
Δ55 (07442-5027) is a bright and wide yellow / yellowish pair in a fairly starry field that lies in southern Puppis near the border with Carina. It can be found 3.2oNW along (PA 322o) from Chi (χ) Carinae or 5.2oSW (PA 231o) from the gloriously bright multiple star Gamma (γ) Velorum (Δ65). When Dunlop discovered this pair, and before the grand constellation of Argo was divided into its more manageable part, the naked-eye star it was simply known as 209 Argûs. Given as 6.6v and 7.6v (6.64V and 7.55V) magnitude, the current position angle of 133o has changed very little since found by Dunlop in 1826, but the separation has slowly decreased from about 60" to 51.9"arc seconds. Spectral classes for both Main Sequence stars are listed as F8 and G0 - corresponding well to the observed colours. It is likely that this pair is attached as both stars show similar proper motion. Δ55 is highly suitable pair even for the smallest of apertures.
NEARBY PLANETARY NEBULA to Δ55
He2-5 / Sa2-17 / ESO 209-1 / PK 264-18.1 / PK 264-12.1 / PNG 264.4-12.7(07473-5115) is a bright but very small planetary nebula in a moderately spartan field within nearby Carina, and is 55'SE (PA 145o) from the wide pair Δ55 - useful here as the field star to find the PNe. He2-5 is 3.0"arcsec across and is listed as 12.3p magnitude. It is easily visible in a 15cm especially I one is using an O-III filter by flicking it across the field.
HJ 4002 (07451-5017) lies in the same field as Δ55 and merely 13.4'NE (PA 40o) away. The magnitudes are 7.5 and 11.5 with the separation being 19.5"arc seconds along PA 91o. John Herschel when discovered the pair lists the separation as 18.0"arcsec and the PA as 87o, but looking at the slow changes both these values seem questionable, and likely this reason that it was deleted in the Index of Double Stars (IDS) in 1961. The good measures, however, between 1913 and 1933 looks like it changed very little, I saw the pair as yellowish and possibly white. Knowledge of the true attachment of the two stars is presently unknown. This is an easy pair in 7.5cm aperture.
Δ56 (07471-4130) is 3.4o SW of ζ Puppis and half-way between Δ51 σ Puppis) and ζ Pup. Magnitudes are 6.9 and 7.7 for this bluish-white duo which are separated by 49.6" along PA 177o. These stars are certainly an optical pair, but the field is quite nice. 7'E is a 9th mag orange star making a nice contrast with all the blue stars in the field. Also note the star in one of the wide 10th mag pairs some 8'N of the main star. This bottom star, 8'NNW of Δ56 is the variable RR Pup (07469-4122), which is an Algol-type eclipsing variable. The light-curve changes between 10.34V and 11.37V mag in the period of 6.4296338 days. Duration of the primary eclipse is 0.83585 days.
R 79 (07472-5905) is a wide and easy pair of 9.0 and 9.8 (8.95 and 9.84V) magnitude that was discovered by Russell on the late evening of the 10th July 1880. Position angle is fixed at 120o though the 32.6"arcsec separation (1991) has decrease from Russell's measure of 35.8"arcsec (PA 299.8o) in 1880. According to the WDS01, the position angle has changed from 300o to 120o between 1880 and 1991 - this might seem significant except that the angle is out by exactly 180o. Russell’s estimated the brightnesses as 9th and 9 1/2th quite close to the more exact magnitudes today. R 79 lies 1.2oW of the nebulae IC 2220 being near the centre of Carina and 4.6oW of Epsilon (υ) Carinae / Avior. Both stars share similar common proper motions and are likely attached. To me this pair looks white and yellowish in a moderately starry field. An interesting pair to look after observing the nebulosity of IC 2220. Another pair to look for is HJ 4000, some 44'NW.
HJ 4018 (07522-5937) is
another triple that is fainter than HJ 4084 mentioned above
that was discovered and first measured by John Herschel in
1837. About 1.3oNNW from the
centre of NGC 2516, the triple lies within a field with two
other similar coloured stars of near equal brightness layed
out in a roughly flat triangle where HJ 4018 is the apex.
HJ 4018’s white primary star is given as 7.5
magnitude with a moderately close 9.7 magnitude companion,
joined with another wider 11th magnitude companion. The
inner pair is HJ 4018AB, separated by 5.1"arcsec
along PA 327o This is visible in
15cm, and possibly in a well-aligned 7.5cm to 10.5cm
telescope. Outer pair HJ 4018AC is much easier, as
10.91 mag. star has the separation is 64"arcsec along PA
259o. Proper motions suggest it
is unlikely any of the stars are associated. Star
‘A’ shows it is an Ap star with Silicon (Si)
lines in its spectrum.
A nice southern pair.
Δ59 (07592-4950) lies in
the far south of Puppis near the Carina border. It can be
found 3.2oSW of the multiple star
Gamma Velorum (Δ65). This pair contain two equal
blue-white stars 6.3 mag. Separated is 16.4" at PA
47o, and little has changed since
Dunlop discovered the pair in 1836. It is uncertain if the
two stars are associated, though I suspected the equal
proper motions of the stars makes this more than likely.
The field is densely populated with 11th and 12th mag
stars. At 11'SE is a collection of 12th magnitude stars
that look like a small open cluster (which it is not).
The field also contains a deep red variable star NR
Pup (07596-5009) some 10'S. The magnitude at maximum is
13.5, which is suspected to drop below 16th. NR Pup is
likely another Mira variable but at present the period and
details of variability are not known.
“Southern Astronomical Delights” © Andrew James 2003 Sydney, Australia