2015A&A...579A..47L


C.D.S. - SIMBAD4 rel 1.7 - 2020.08.15CEST13:31:16

2015A&A...579A..47L - Astronomy and Astrophysics, volume 579A, 47-47 (2015/7-1)

Type II Cepheids in the Milky Way disc. Chemical composition of two new W Virginis stars: DD Vel and HQ Car.

LEMASLE B., KOVTYUKH V., BONO G., FRANCOIS P., SAVIANE I., YEGOROVA I., GENOVALI K., INNO L., GALAZUTDINOV G. and DA SILVA R.

Abstract (from CDS):

A robust classification of Cepheids into their different sub-classes and, in particular, between classical and Type II Cepheids, is necessary to properly calibrate the period-luminosity relations and for populations studies in the Galactic disc. Type II Cepheids are, however, very diverse, and classifications based either on intrinsic (period, light curve) or external parameters (e.g., [Fe/H], |z|) do not provide a unique classification. We want to ascertain the classification of two Cepheids, HQ Car and DD Vel, that are sometimes classified as classical Cepheids and sometimes as Type II Cepheids. To achieve this goal, we examine both their chemical composition and the presence of specific features in their spectra. We find emission features in the Hα and in the 5875.64Å HeI lines that are typical of W Vir stars. The [Na/Fe] (or [Na/Zn]) abundances are typical of thick-disc stars, while BL Her stars are Na-overabundant ([Na/Fe]>+0.5dex). Finally, the two Cepheids show a possible (HQ Car) or probable (DD Vel) signature of mild dust-gas separation that is usually observed only in long-period type II Cepheids and RV Tau stars. These findings clearly indicate that HQ Car and DD Vel are both Type II Cepheids from the W Vir sub-class. Several studies have reported an increase in the Cepheids' abundance dispersion towards the outer (thin) disc. A detailed inspection of the Cepheid classification, in particular for those located in the outer disc, will indicate whether this feature is real or simply an artefact of the inclusion of type II Cepheids belonging to the thick disc in the current samples.

Abstract Copyright:

Journal keyword(s): stars: abundances - stars: atmospheres - stars: variables: Cepheids

Simbad objects: 21

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Number of rows : 21

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* IX Cas WV* 00 04 50.8166633529 +50 14 05.538514833   12.04 11.36     F7 52 0
2 V* QQ Per cC* 02 54 40.3969908370 +51 49 28.676583863           ~ 27 0
3 V* RV Tau Mi* 04 47 06.7238218181 +26 10 45.530144720   11.00 9.80     K0 265 0
4 V* DY Ori RV* 06 06 14.9086299520 +13 54 19.144206036   11.709 11.29     ~ 45 0
5 V* ST Pup pA* 06 48 56.4137309745 -37 16 33.336632924   10.47 9.28 9.89 9.29 G2I 81 0
6 V* SZ Mon pA* 06 51 27.8478992210 -01 22 15.961057167   10.61 9.76   9.109 F8(e) 59 0
7 V* CO Pup WV* 08 26 11.9558350867 -30 17 08.328985204   11.86 10.74     ~ 22 0
8 V* DD Vel WV* 09 12 09.6340277622 -50 22 33.612960439           ~ 30 0
9 V* HQ Car cC* 10 20 31.9898303153 -61 14 57.414334235   12.50 11.7     ~ 25 0
10 V* W Vir WV* 13 26 01.9928122043 -03 22 43.429880244   10.33 9.46 9.29 9.393 F2Ibe 280 0
11 HD 129981 WV* 14 46 33.6357510124 -32 10 15.268785469   8.92 8.27 9.14   G5I/IIIpCH 94 0
12 V* RX Lib WV* 15 42 00.0542433613 -20 46 45.905716461     11.60     F9 22 0
13 V* RT TrA WV* 16 34 30.8912790319 -63 08 00.815992650   10.42 9.70     G2Ib-II: 54 0
14 V* CC Lyr cC* 18 33 57.4124417680 +31 38 24.187628709   12.98 12.46     hF4mA:CH+1 42 0
15 V* HP Lyr pA* 19 21 39.0675162741 +39 56 08.200273318   11.12 10.38 10.15 9.615 A3Ia/Iab 49 1
16 V* RR Lyr RR* 19 25 27.9123232234 +42 47 03.690634101   7.36   7.6   A8-F7 882 0
17 V* V1711 Sgr cC* 20 01 07.9860335196 -30 30 38.908194700   11.26 10.67     F6CH+2 35 0
18 V* TW Cap WV* 20 14 28.4159505661 -13 50 07.886308747   11.0 10.7     F4Ib 68 0
19 V* TX Del WV* 20 50 12.6956652311 +03 39 08.365333296   9.95 8.84     F8 93 0
20 V* MZ Cyg WV* 21 21 54.7239732299 +37 27 33.099617919   13.16 12.14     G1 34 0
21 V* AU Peg WV* 21 24 00.2422967380 +18 16 43.776787622   10.03 9.18     F8 88 0

    Equat.    Gal    SGal    Ecl

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2020.08.15-13:31:16

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