| Issue |
A&A
Volume 587, March 2016
|
|
|---|---|---|
| Article Number | C3 | |
| Number of page(s) | 1 | |
| Section | Galactic structure, stellar clusters and populations | |
| DOI | https://doi.org/10.1051/0004-6361/201220824e | |
| Published online | 19 February 2016 | |
Variable stars in the globular cluster NGC 7492⋆ (Corrigendum)
New discoveries and physical parameter determination
1
European Southern Observatory,
Karl-Schwarzschild-Straße 2,
85748
Garching bei München,
Germany
e-mail: robertofiguera@gmail.com, dan.bramich@hotmail.co.uk
2
SUPA, School of Physics and Astronomy, University of St.
Andrews, North
Haugh, St. Andrews,
KY16 9SS,
UK
3
Instituto de Astronomía, Universidad Nacional Autónoma de
México, Apdo. Postal
70-264, México D.
F.
CP
04510,
Mexico
4
Indian Institute of Astrophysics, Bangalore, 560034
Karnataka,
India
Key words: globular clusters: individual: NGC 7492 / stars: variables: RR Lyrae / blue stragglers / stars: abundances / stars: horizontal-branch / errata, addenda
Equation (9), representing the phase φ(t) at time t of a periodic variable undergoing a period change, is erroneous. This equation should instead read 
(1)where NE(t) is the number of cycles elapsed at time t since a reference epoch E. The quantity NE(t) for a constant rate of period change is given by ![\begin{equation} N_{E}(t) = \frac{1}{\beta} \ln \left[ 1 + \frac{\beta}{P_{0}} (t - E) \right], \end{equation}](/articles/aa/full_html/2016/03/aa20824e-12/aa20824e-12-eq6.png)
(2)
where β is the period change rate and P0 is the period at the epoch E.
Consequently our derived period change rate for the RR Lyrae star V2 in NGC 7492 is wrong. Repeating the analysis with the correct equations, we obtain P0 = 0.412119 d at epoch E = 2 453 284.2652 d and β ≈ 2.6 × 10-7 d d-1 (or β ≈ 95 d Myr-1). We find that the phased light curve for V2 using these new parameters (and equations) is further improved.
© ESO, 2016
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