The case StHA 154
Posted: Sat Jul 16, 2022 3:21 pm
Our colleague Keith Shank got a spectrum of StHA 154 and put the finger on an interesting behavior.
StHA 154 = 2MASS J18432793+1930053 in SIMBAD is a poorly studied symbiotic star with 4 references in Simbad.
Keith obtained a spectrum of a red giant, spectral type M7-8 (from TiO1 index) with no emission.
He confirmed the identification taking spectra of the two brightest neighbors of the target. The early type of these two stars excludes that they can be StHa 154.
(Keith Shank)
Woody Sims and Bob Buchheim confirmed the identification.
Spectra: https://aras-database.github.io/database/stha154.html
StHA 154 was discovered as en emission line star by Stephenson (1986)
Munari & Zwitter (2002) published a spectrum showing a typical symbiotic (nuclear powered) with notably He II, Raman OVI , [OIII]
The coordinates of the various observations (Stepenson, Munari+, Shank+) are consistent. The probability of an error is very low.
We must admit (at a high probability) that this object show a significant variation of its spectrum at a time scale of less than 25 years.
Such variations are well established for accretion powered symbiotics (see e.g. CH Cyg, SU Lyn, ...)
In the case of a classical (nuclear powered symbiotics) this is an atypical behavior. We can find an example with V407 Cyg (symbiotic nova - perhaps recurrent- event in 2010 , showing now only the variations of a classical Mira variable).
After consultation of Dr Rudolf Gàlis, it is proposed a long term monitoring (photometry and low resolution spectroscopy) of this peculiar object over several years in order to detect pulse variations.
The optimal cadency should be a spectrum per 10 days (about 30 spectra for a time scale of 300 days the order of magnitude of mirae periods)
spectra to be send to francoismathieu.teyssier at gmail.com and copy to arasdatabase at gmail.com
Congratulations to Keith for this interesting finding and thanks to Bob and Woody for the confirmation. An excellent collective work!
Best,
François
StHA 154 = 2MASS J18432793+1930053 in SIMBAD is a poorly studied symbiotic star with 4 references in Simbad.
Keith obtained a spectrum of a red giant, spectral type M7-8 (from TiO1 index) with no emission.
He confirmed the identification taking spectra of the two brightest neighbors of the target. The early type of these two stars excludes that they can be StHa 154.
(Keith Shank)
Woody Sims and Bob Buchheim confirmed the identification.
Spectra: https://aras-database.github.io/database/stha154.html
StHA 154 was discovered as en emission line star by Stephenson (1986)
Munari & Zwitter (2002) published a spectrum showing a typical symbiotic (nuclear powered) with notably He II, Raman OVI , [OIII]
The coordinates of the various observations (Stepenson, Munari+, Shank+) are consistent. The probability of an error is very low.
We must admit (at a high probability) that this object show a significant variation of its spectrum at a time scale of less than 25 years.
Such variations are well established for accretion powered symbiotics (see e.g. CH Cyg, SU Lyn, ...)
In the case of a classical (nuclear powered symbiotics) this is an atypical behavior. We can find an example with V407 Cyg (symbiotic nova - perhaps recurrent- event in 2010 , showing now only the variations of a classical Mira variable).
After consultation of Dr Rudolf Gàlis, it is proposed a long term monitoring (photometry and low resolution spectroscopy) of this peculiar object over several years in order to detect pulse variations.
The optimal cadency should be a spectrum per 10 days (about 30 spectra for a time scale of 300 days the order of magnitude of mirae periods)
spectra to be send to francoismathieu.teyssier at gmail.com and copy to arasdatabase at gmail.com
Congratulations to Keith for this interesting finding and thanks to Bob and Woody for the confirmation. An excellent collective work!
Best,
François