2018A&A...619A...2M


C.D.S. - SIMBAD4 rel 1.7 - 2020.01.28CET15:34:15

2018A&A...619A...2M - Astronomy and Astrophysics, volume 619A, 2-2 (2018/11-1)

Planets around evolved intermediate-mass stars. II. Are there really planets around IC 4651 No. 9122, NGC 2423 No. 3, and NGC 4349 No. 127?

MENA E.D., LOVIS C., SANTOS N.C., DA SILVA J.G., MORTIER A., TSANTAKI M., SOUSA S.G., FIGUEIRA P., CUNHA M.S., CAMPANTE T.L., ADIBEKYAN V., FARIA J.P. and MONTALTO M.

Abstract (from CDS):


Aims. The aim of this work is to search for planets around intermediate-mass stars in open clusters using data from an extensive survey with more than 15yr of observations.
Methods. We obtain high-precision radial velocities (RV) with the HARPS spectrograph for a sample of 142 giant stars in 17 open clusters. We fit Keplerian orbits when a significant periodic signal is detected. We also study the variation of stellar activity indicators and line-profile variations to discard stellar-induced signals.
Results. We present the discovery of a periodic RV signal compatible with the presence of a planet candidate in the 1.15Gyr open cluster IC 4651 orbiting the 2.06M star No. 9122. If confirmed, the planet candidate would have a minimum mass of 7.2MJ and a period of 747-days. However, we also find that the full width at half maximum (FWHM) of the cross-correlation function (CCF) varies with a period close to the RV, casting doubts on the planetary nature of the signal. We also provide refined parameters for the previously discovered planet around NGC 2423 No. 3, but show evidence that the bisector inverse slope (BIS) of the CCF is correlated with the RV during some of the observing periods. We consider this fact as a warning that this might not be a real planet and that the RV variations could be caused by stellar activity and/or pulsations. Finally, we show that the previously reported signal by a brown dwarf around NGC 4349 No. 127 is presumably produced by stellar activity modulation.
Conclusions. The long-term monitoring of several red giants in open clusters has allowed us to find periodic RV variations in several stars. However, we also show that the follow-up of this kind of stars should last more than one orbital period to detect long-term signals of stellar origin. This work highlights the fact that although it is possible to detect planets around red giants, large-amplitude, long-period RV modulations do exist in such stars that can mimic the presence of an orbiting planetary body. Therefore, we need to better understand how such RV modulations behave as stars evolve along the red giant branch and perform a detailed study of all the possible stellar-induced signals (e.g., spots, pulsations, granulation) to comprehend the origin of RV variations.

Abstract Copyright: © ESO 2018

Journal keyword(s): stars: individual: IC 4651 No. 9122 - stars: individual: NGC 2423 No. 3 - stars: individual: NGC 4349 No. 127 - planetary systems - planets and satellites: detection - open clusters and associations: general

VizieR on-line data: <Available at CDS (J/A+A/619/A2): stars.dat tableb1.dat tableb2.dat tableb3.dat>

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 HD 13189 * 02 09 40.1721335781 +32 18 59.160743793   9.04 7.56     K1II-III 67 1
2 HD 18438 * 03 06 07.8391765913 +79 25 06.721309149   7.05 5.49     M2.5III 35 1
3 V* EK Eri BY* 04 20 38.6418116586 -06 14 45.579829233   7.036 6.154     K0III 107 0
4 Cl Melotte 25 OpC 04 26 54.00 +15 52 00.0           ~ 2608 0
5 * alf Tau LP? 04 35 55.23907 +16 30 33.4885 4.32 2.40 0.86 -0.37 -1.31 K5+III 1175 1
6 HD 36384 V* 05 39 43.7068278683 +75 02 37.949351724   7.763 6.170     M0III 32 0
7 HD 41004 ** 05 59 49.6473573887 -48 14 22.805780232   9.49 8.65     K1IV 150 1
8 HD 41004B * 05 59 49.649 -48 14 22.88   13.85 12.33     M 48 1
9 HD 41004A * 05 59 49.649 -48 14 22.88           ~ 25 1
10 NGC 2422 OpC 07 36 35 -14 29.0           ~ 201 0
11 NGC 2423 OpC 07 37 06 -13 52.3           ~ 115 0
12 BD-13 2130 * 07 37 09.2333520617 -13 54 23.954320858   11.31 10.04     G5IV-V/K2III 48 1
13 * bet Gem PM* 07 45 18.94987 +28 01 34.3160 3.00 2.14 1.14 0.39 -0.11 K0IIIb 1042 1
14 NGC 2682 OpC 08 51 18 +11 48.0           ~ 1999 0
15 BD+20 2457 * 10 16 44.8673242080 +19 53 29.009601473   10.99 9.74     K2 44 1
16 * mu. UMa SB* 10 22 19.7397659 +41 29 58.269105 6.53 4.64 3.05 1.76 0.80 M0III 290 0
17 NGC 4349 OpC 12 24 08 -61 52.3   8.01 7.4     ~ 85 0
18 NGC 4349 127 * 12 24 35.4709937902 -61 49 11.859118499   12.85 10.82     ~ 36 1
19 * alf Boo RG* 14 15 39.67207 +19 10 56.6730 2.46 1.18 -0.05 -1.03 -1.68 K1.5IIIFe-0.5 2111 0
20 IC 4651 OpC 17 24 49 -49 56.0           ~ 308 0
21 CD-49 11404 * 17 24 50.0711175768 -49 56 56.080865466   11.5 10.7     ~ 25 0

    Equat.    Gal    SGal    Ecl

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2020.01.28-15:34:15

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