Tue, 05/05/2020 - 17:28
I'm working on an image of Palomar 4 with an 8" scope. It's brightest star seems brighter than I see in other pictures. All of P4's brightest stars are quite red. I'm not an active variable star observer, but I know where the expertise is! Can any kind soul help me determine whether P4's stars are LPV, and in particular this brightest star?
Val Ricks
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If the intended star is the one in your image at the bottom (west) edge of the cluster, then yes, it is a known long-period variable. Coordinates are: 11 29 12.4 +28 58 15 (J2000). This appears in VSX as CSS_J112912.3+285815. There are three LAMOST spectra of the star, but only one is good. The LAMOST DR5 catalogue indicates a spectral type of M0, which I confirm approximately (no strong TiO bands). VSX shows the range as about 2 magnitudes and a period of 150 days. Hope that helps.
\Brian
As Brian pointed out, it was a long period variable.
This one and a similar one 31" apart were known before CRTS so I have changed their primary names and revised their information adding plots. One is SRB and the other is SRA.
They are now Pal4 V002 and Pal4 V001.
Cheers,
Sebastian
I see the VSX entry with all that beautiful information. Thanks to you both, Sebastian and Brian. Got a bead on Pal4 V001, also. Wonderful!
May I post some of this information with the image on my blog, with full credit?
Val
Of course Val. You are always free to make use of any information we share here.
I'm glad you were able to observe those variables in that GC.
I take the chance to mention that globular cluster variables are not systematically included in VSX, we have only added objects published through survey lists and some particularly interesting targets. So you won't find most of the GC variables in our catalogue.
Cheers,
Sebastian