Estelle's Star

[erick (Eric)]

We had a robust discussion a few months ago about Sydney Observatory's Name-A-Star program:-

http://www.iceinspace.com.au/forum/s...ad.php?t=60378

I had a discussion with the Observatory staff member, paid my tax-deductible donation, and a star in the Sydney Southern Star Catalogue has been named in their records, a star to which I can feel a certain attachment.

I give you "Estelle's Star".

Estelle is my big sister who I never knew. She was born four years before I was, and lived only three days. The name Estelle is reportedly from an old French name which was derived from Latin stella, meaning "star".

I sought a star close to the Jewel Box (NGC 4755). I always associate the Jewel Box with my father (died in 1999, before I ever saw the Jewel Box). He had mentioned to me, after seeing it through a telescope once when I was young, that I had to see it one day. Estelle's Star is in Crux, a simple star hop from the Jewel Box and at the top of a nice "kite" asterism.

RA 12hr 49m 27.45s, Dec -60deg 41m 57.11 s (J2000.) Mag 8.94

Easily seen in a telescope, can be glimpsed in 10x50 binoculars under dark skies.

Have a look if you wish (no fee payable ) and think of Estelle.

Many thanks to the helpful folks at the Sydney Observatory. The Certificate is lovely and says "A loving memorial for our big sister". I am looking forward to showing this and the star to my younger sister.

Stellarium region and photos attached.

Acknowledgment:-

B/W images from the STScI Digitized Sky Survey

http://stdatu.stsci.edu/cgi-bin/dss_form

Colour images cropped from images acquired by avandonk and published on IIS (many thanks Bert)

[supernova1965 (Warren)]

A great memorial

[Jen]

Awwwwww thats so sweet Eric

[stephenb (Stephen)]

I read the previous thread in great detail, and overall I have no issue with the concept. Your "stellar" memorial to your sister is a wonderful thought. I may look into it for our family, for similar reasons.

[mithrandir (Andrew)]

That's a fitting way to remember a sister. I'll look into doing the same for mine who we lost to melanoma last year.

I think you'll find Estelle's Star is TYC 8988-1196-1.

[DavidU (Dave)]

A very cool thing to do mate.

[erick (Eric)]

Originally Posted by mithrandir

I think you'll find Estelle's Star is TYC 8988-1196-1.

Thanks Andrew. I expected it would be given a number somewhere, but I didn't know where to look. (What catalog is this number from, please - EDIT Update, found it - the Tycho-2 catalog - http://archive.eso.org/ASTROM/TYC-2/readme.htm ).

I think the name I know it by is easier to remember

[erick (Eric)]

I don't have enough knowledge of this catalog:-

http://archive.eso.org/skycat/servers/ASTROM

I can find it, and extract lots of data fields, but I cannot determine some more information such as distance to the star and proper motion. Can anyone extract this information for me, please? Thanks.

[mithrandir (Andrew)]

Originally Posted by erick

I don't have enough knowledge of this catalog:-

http://archive.eso.org/skycat/servers/ASTROM

I can find it, and extract lots of data fields, but I cannot determine some more information such as distance to the star and proper motion. Can anyone extract this information for me, please? Thanks.

Did you try VizieR? All the fields have explanations, but I can't see a distance. Anything beyond about 1000 parsecs is unlikely to have a distance unless it is a periodic variable like a Cephid.

Aladin (requires Java) has an image here. (Hope that doesn't have a cookie and works.)

If you start from http://vizier.hia.nrc.ca/ select Tycho-2 catalog, put the RA and Dec in the "Target" box, at the bottom of the result page are the Aladin links.

[Robh (Rob)]

The trigonometric parallax for Estelle's star (HD 111363) is given here as 1.5 mas (milli-arcseconds) ...
http://vizier.hia.nrc.ca/viz-bin/Viz...&recno=2334886

This would put its distance as 1/0.0015 pc (parsecs) ~ 667 pc.
Also equates to 667 x 3.26 ~ 2200 light years.

Regards, Rob

[erick (Eric)]

Thanks Andrew and Rob. I'll look through the data.

[erick (Eric)]

I've been trying to estimate absolute magnitude.

Using apparent magnitude (m) of 8.94, distance (D) approx 670 parsec and

M = m - 5 ((Log10D) - 1)

I get an absolute magnitude of approx -0.2.

So I make Estelle's Star to be about 100 times more luminous than the Sun (M = 4.8) and 4 times more luminous than Sirius (M = 1.4).

Does my maths seem right?

The only colour image I have shows a blue/white star. What spectral type would it be, and approximate surface temperature range, given that absolute magnitude? Around A on the Main Sequence? Maybe around 10,000K+?

Thanks
Eric

[mithrandir (Andrew)]

With the Johnson Vmag=9.039
Parallax 1.5mas
and the alternate formula

M = m+5(log10(p)+1) = 9.039+5(log(1.5/1000)+1) = -0.081

SpType B3 III - extremely luminous and blue

[erick (Eric)]

Thanks Andrew

That's a neat star! I'm very happy with it.

[erick (Eric)]

OK, final post.

Tried my 20x80 binoculars on this star last night. That magnification nicely frames the area and the star was easily detected. Looks bluish.

[DavidU (Dave)]

Nice one Erik. Good to see it with your own eyes, it makes it more real.