EC 11507-2253

EC 11507-2253 is a post-AGB star located about 81,000 light years, or 25 kpc, away from Earth in the constellation of Corvus. Located in the distant galactic halo, over 50,000 light years above the galactic plane, EC 11507-2253 is very isolated and the rest of its life (likely only a few tens of thousands of years) will be spent in the halo as well, far from much of the stellar population. The apparent magnitude is only about 15, and it was only discovered in 1997 in a survey for blue objects at high latitudes (above the galactic plane).[3]

EC 11507-2253
Observation data
Epoch J2000      Equinox J2000
Constellation Corvus
Right ascension 11h 53m 15.905s[1]
Declination −23° 09′ 53.67″[1]
Apparent magnitude (V) 15.12[2]
Characteristics
Evolutionary stage Post-AGB Star
Spectral type B5[2]
U−B color index -0.63[3]
B−V color index -0.09
Astrometry
Proper motion (μ) RA: −1.298[1] mas/yr
Dec.: −1.065[1] mas/yr
Parallax (π)−0.0012 ± 0.0375 mas[1]
Distance17,329[1] pc
Details
Mass0.55[2] M☉
Radius4.0[1] R☉
Luminosity1,222[1] L☉
Surface gravity (log g)2.6[2] cgs
Temperature15,500[2] K
Metallicity [Fe/H]−1.40[1] dex
Rotational velocity (v sin i)≤10[2] km/s
Other designations
2MASS J11531589-2309536
Database references
SIMBADdata

Properties
An artist's impression of EC 11507-2253

EC 11507-2253 is quite a hot post-AGB star. Initial analysis of its spectrum upon its discovery in 1997 yielded a spectral type of B5.[3] Analysis of its spectrum in 2005 has revealed a temperature of about 15,500 K, which makes sense given its spectral type.[2]

In 2015, a distance catalogue of post-AGB stars based on an assumed luminosity given the post-AGB star type and location was made, which included EC 11507-2253, which was assigned an estimated luminosity of 1,700 L☉ based on its status as an outer halo post-AGB star. This also yielded its distance value of 24.93 kpc.[4] Modelling published with Gaia Data release 3 gives a similar luminosity of 1,222 L☉ and a radius of 4 R☉.[1]

References
  1. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. Lynn, B. B.; Keenan, F. P.; Dufton, P. L.; Rolleston, W. R. J.; Smoker, J. V.; Ryans, R. S. I.; Kilkenny, D.; O'Donoghue, D.; Hambly, N.; McGillivray, H. T. (2005-11-01). "High-resolution spectroscopic observations of post-asymptotic giant branch candidates from the Edinburgh-Cape Survey". Monthly Notices of the Royal Astronomical Society. 363 (3): 911–917. Bibcode:2005MNRAS.363..911L. doi:10.1111/j.1365-2966.2005.09496.x. ISSN 0035-8711. S2CID 59468530.
  3. Kilkenny, D.; O'Donoghue, D.; Koen, C.; Stobie, R. S.; Chen, A. (1997-06-01). "The Edinburgh-Cape Blue Object Survey - II. Zone 1 - the North Galactic CAP". Monthly Notices of the Royal Astronomical Society. 287 (4): 867–893. Bibcode:1997MNRAS.287..867K. doi:10.1093/mnras/287.4.867. ISSN 0035-8711.
  4. Vickers, Shane B.; Frew, David J.; Parker, Quentin A.; Bojičić, Ivan S. (2015-02-01). "New light on Galactic post-asymptotic giant branch stars - I. First distance catalogue". Monthly Notices of the Royal Astronomical Society. 447 (2): 1673–1691. Bibcode:2015MNRAS.447.1673V. doi:10.1093/mnras/stu2383. ISSN 0035-8711.
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