F9 star
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by
bluemagi
On the sdss this is listed as a galaxy. The spectrum is listed as a F9 star. Thanks
Posted
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by
mlpeck
in response to bluemagi's comment.
This is #NGC 4344 and definitely a galaxy. The SDSS spectro pipeline fit a number of star, galaxy and QSO templates to each spectrum and assigned the class according to which set of templates best fit the spectrum. Sometimes that didn't work very well. This spectrum looks post-starbursty to me, which is a class of galaxies that they had no good templates for.
Another thing that happened sometimes was that a foreground star was accidentally targeted and the resulting spectrum is a mixture of star and galaxy light. In cases like that sometimes the spectrum is classified as a star and sometimes as a galaxy. In this case though the redshift is too high to be a very plausible star from our galaxy.
Posted
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by
Budgieye
moderator
Yeah, galaxy, with nuclear ring. Quite close at z=0.003, but I would think that the absorption lines should have given the software a good handle that it is a galaxy,
http://legacysurvey.org/viewer/jpeg-cutout/?ra=185.9057&dec=17.5391&zoom=13&layer=decals-dr2
http://skyserver.sdss.org/dr9/en/get/specById.asp?id=2925186435269027840
Posted
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by
mlpeck
in response to Budgieye's comment.
but I would think that the absorption lines should have given the
software a good handle that it is a galaxy,That should have been the case, but the SDSS spectro pipeline lacked good templates for post-starburst galaxies & it often had trouble with spectra with strong Balmer absorption lines. In this case they were lucky to have stellar templates that gave a correct redshift even though the software misidentified it as a star.
Posted
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by
Budgieye
moderator
Thank you for the info , mipeck 😃
Posted