2009A&A...507.1621P


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.04CEST19:59:17

2009A&A...507.1621P - Astronomy and Astrophysics, volume 507, 1621-1624 (2009/12-1)

Helium lines in RR Lyrae spectra.

PRESTON G.W.

Abstract (from CDS):

During a comparative study of atmospheric phenomena that occur during the pulsation cycles of 10 RRab stars I unexpectedly found helium lines in emission and/or absorption in all 10 stars during rising light. The progression of events in the time-evolution of the helium spectrum differs in detail from star to star, but 9 of the 10 stars share a number of general characteristics, illustrated approximately by the behavior of RV Oct described in this Note. My long-term aim is to provide a comprehensive empirical description of atmospheric phenomena that take place during the pulsation cycles of RRab stars. The short-term goal of this paper is to inform readers that measurements of helium lines place new constraints on shock-wave models for RRab stars.
Result. presented here are based on measurements and analysis of observations made with the echelle spectrograph of the du Pont 2.5-m telescope at Las Campanas Observatory. A general pattern of behavior emerges albeit with significant star-to-star variation. He I λ5376 (D3) appears first as a pure emission feature, unlike the Balmer lines for which the emission profile is always overlain initially by strong redward-displaced absorption. The phase of maximum D3 emission coincides approximately with that of Hα, but the duration of conspicuous D3 emission (in excess of the local continuum) is less than 15mn, approximately half the duration of similarly defined Hα emission. The emission phase is followed by the appearance, first, of redward-displaced absorption, and shortly thereafter by a second violet-displaced absorption component that strengthens with advancing phase. Both absorption components gradually weaken and disappear after radial-velocity minimum, which lags luminosity maximum by no more than 0.01P as discussed in Sect. 3. However, bona fide HeI λ5876 emission flux in excess of the local continuum flux reappears near maximum light for some stars in the sample and persists for about 45mn. The radial velocities of the initial and final He I λ5876 emission features differ little from the time-average value of the metallic-line radial velocities for RV Octantis. However, the absorption features appear to distort the location of the emission centroid, when they are strong.

Abstract Copyright:

Journal keyword(s): stars: variables: RR Lyr - shock waves

Simbad objects: 18

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Number of rows : 18

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 V* X Ari RR* 03 08 30.8844194016 +10 26 45.221908919 9.45 9.25 8.97     F0.5 266 0
2 V* U Mon RV* 07 30 47.4734611972 -09 46 36.788534824 8.22 7.00 5.82     G8/K0Ib/II 193 0
3 V* CD Vel RR* 09 44 38.2453720689 -45 52 37.110603440   12.93 11.86     F 28 0
4 V* WY Ant RR* 10 16 04.9458687043 -29 43 42.415589871   11.03 10.78     A8.7 110 0
5 V* DT Hya RR* 11 54 00.1884461021 -31 15 40.038896661     12.99     ~ 18 0
6 V* AS Vir RR* 12 52 45.8687202862 -10 15 36.378519137   12.37 11.90     A6 57 0
7 V* W Vir WV* 13 26 01.9928122043 -03 22 43.429880244   10.33 9.46 9.29 9.393 F2Ibe 279 0
8 V* RV Oct RR* 13 46 31.7424718827 -84 24 06.384600100   11.39 10.94     ~ 73 0
9 BPS CS 22874-0009 * 14 34 23.1650238622 -26 17 37.593258136   13.92 13.58     ~ 16 0
10 V* XZ Aps RR* 14 52 05.4228175938 -79 40 46.570073449           ~ 46 0
11 V* BS Aps RR* 16 20 51.5039464474 -71 40 15.720535922   12.48 12.03     ~ 34 0
12 V* UV Oct RR* 16 32 25.5362144318 -83 54 10.494808743   9.80 9.44     A8/F0Ia/ab(w) 100 0
13 V* S Ara RR* 17 59 10.7333917557 -49 26 00.455338511   11.01 10.73     A3 90 0
14 V* AC Her pA* 18 30 16.2374666779 +21 52 00.618442618 8.00 7.79 7.01     F4Ibp 316 0
15 V* RR Lyr RR* 19 25 27.9123232234 +42 47 03.690634101   7.36   7.6   A8-F7 880 0
16 V* V1645 Sgr RR* 20 20 44.4774331766 -41 07 05.784834957   11.72 11.39     ~ 26 0
17 V* Z Mic RR* 21 16 22.7046715445 -30 17 03.067666365   11.58 11.37     F2.5II 52 0
18 V* TY Gru RR* 22 16 39.4203774936 -39 56 17.948911227   14.64 14.10     ~ 30 0

    Equat.    Gal    SGal    Ecl

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2020.07.04-19:59:17

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