The distance of M90 is off by 15Mpc a factor of 15

[dave1235]

The galaxy M90 is not displayed as being in the Virgo Cluster but is in the local group. Here is a quote from Wiki which is in agreement with other sources.

Messier 90 may be the ultimate silly example that can be used to demonstrate how NED fails to calculate distances accurately. This is an object in the Virgo Cluster that is interacting with the cluster's intracluster medium. Based on the distance to Messier 87, M90 should be at approximately 16 Mpc. Ned lists the distance as 1.2 Mpc. If M90 really was at that distance, it would lie within the Local Group. Dr. Submillimeter 23:09, 15 January 2007 (UTC)

http://en.wikipedia.org/wiki/User_talk:WilliamKF

Also...

The spectrum of Messier 90 is blueshifted, which indicates that it is moving towards the Earth[1]. In contrast, the spectra of most other galaxies are redshifted. The blueshift was originally used to argue that Messier 90 was actually an object in the foreground of the Virgo Cluster. However, since the phenomenon was limited mostly to galaxies in the same part of the sky as the Virgo Cluster, it appeared that this inference based on the blueshift was incorrect. Instead, the blueshift is thought to be evidence for the large range in velocities of objects within the Virgo Cluster itself[4].

http://en.wikipedia.org/wiki/Messier_90

Other sources that quote the Virgo cluster distance
http://www.seds.org/messier/m/m090.html
http://www.redorbit.com/images/gallery/messier_objects/m_90/104/21/index.html
http://www.intercom.net/user/shaffer/messier/m90.html
http://diskwl.blogspot.com/
http://astro.ib-host.net/messier.htm


Thanks to anyone that has spent time working on Celestia

David

PS
If you might be interested in a unique non-mathematical treatment of relativity that will develop your emotional sense of spacetime go to my website http://geocities.com/spacetimeexercises

[t00fri]

David,

thanks for pointing this error out. Of course, I am aware of the well-known misassignment of the M 90 distance in the literature since a long time. I was also aware of the astrophysical reasons for the misassignment .

Since I generated all distances in deepsky.dsc without human interference by merging data catalogs for /six/ different distance determination methods, some isolated values invariably fall through the applied filters here and there. ..

As an aside, when it comes to serious scientific arguments, I always ignore anonymous Wiki articles as a matter of principle! Scientific argumentation has to be invariably connected to names of scientists who stand with their "good name" for the quality of their results!

In that sense, let me recall a pretty old respective article in 'The Astronomical Journal' that clears up the reasons for the familiar misassignment of the M90 distance using the (usually well-trusted) Tully-Fisher (TF) method.
http://www.shatters.net/~t00fri/images/stauffer.pdf

Of course, I shall correct that distance for the forthcoming
1.5.0 release.

Bye Fridger

[dave1235]

Fridger,

I wish I could say something intelligent about extragalactic distance indicators but at this point I?€™m just trying to get my head around what exists out there. Lacking a strong left hemisphere I focus on trying to develop an emotional sense of things, which Celestia is perfect for by the way. I really believe in this open source, grassroots sort of stuff and am glad to make this teeny-weeny contribution.

Concerning your aside, keep in mind Wiki often has consensus working for it?€¦ however just like when sitting on a public toilette seat, timing can be important.

Happy programming,
David
PS, let me thank you directly for all the time you are obviously putting into this project.

[dave1235]

I don?€™t know how much time your prepared to spend fine tuning the distances of different galaxies but?€¦.
While I haven?€™t been looking, I noticed a second galaxy in the Virgo cluster that may be misplaced in Celestia,(by a factor of three) as a result of it not being a typical galaxy.

NGC 4438 (Apparent Mag 10.9) in Celestia is placed at 5 Mpc and its neighbouring galaxy is placed at 15 Mpc.

While most don?€™t think they are interacting they still talk about them being close enough to each other to be possibly interacting. They also talk about them being near the center of the Cluster.

The below link also talks about the galaxy being HI defiant which I understand would throw off the standard automatic calculation formulas.

http://www.aanda.org/index.php?option=com_base_ora&access=standard&Itemid=129&url=articles/aa/abs/2005/38/aa1389-04/aa1389-04.html

NGC 4438 is a highly perturbed spiral with a stellar tidal tail and extraplanar molecular gas, now very HI deficient, crossing the center of the Virgo cluster at high speed.

[url]
http://www.noao.edu/outreach/aop/observers/n4438.html[/url]

These interacting galaxies (NGC 4438 on the left and NGC 4435 to the right) lie in the heart of the Virgo cluster?€¦?€¦ close encounters with other galaxies and the heavyweight - M87?€¦?€¦ These galaxies are around 40 million light years away.

[url]
http://www.daviddarling.info/encyclopedia/E/Eyes.html[/url]

There is debate about whether NGC 4435 and NGC 4438 are interacting, with most authorities doubting it.

[url]
http://www.astrooptik.com/Bildergalerie ... GC4438.htm[/url]

NGC 4438 may be deformed by its neighbour galaxy NGC 4435 but some other people think that NGC 4438 is already a merged galaxy and NGC 4435 is far behind NGC 4438 and not interacting with NGC 4438.

A PDF file

http://www.journals.uchicago.edu/ApJ/journal/issues/ApJL/v623n1/19172/19172.web.pdf

NGC 4438 (Arp 120) in the center of the Virgo Cluster

[t00fri]

Here is a comparison with your nice image of ngc 4435 and 'friends' above in Celestia:



Bye Fridger

[dave1235]

It is pretty good eh?
I'm a little surprised.