HR 10 as seen by CHEOPS and TESS: revealing δ Scuti pulsations, granulation-like signal and hint for transients

S. J. A. J. Salmon; V. Van Grootel; S. Sulis; Gy M. Szabó; A. Brandeker; C. Broeg; D. Ehrenreich; S. Hoyer; S. G. Sousa; F. Kiefer; D. Gandolfi; D. Nardiello; S. Charpinet; A. Bonfanti; T. G. Wilson; Y. Alibert; R. Alonso; G. Anglada; T. Bárczy; D. Barrado Navascues; S. C. C. Barros; W. Baumjohann; M. Beck; T. Beck; W. Benz; N. Billot; X. Bonfils; L. Borsato; J. Cabrera; V. Cessa; S. Charnoz; A. Collier Cameron; C. Corral Van Damme; Sz Csizmadia; P. E. Cubillos; M. B. Davies; M. Deleuil; L. Delrez; O. D. S. Demangeon; B. O. Demory; A. Erikson; A. Fortier; L. Fossati; M. Fridlund; M. Gillon; M. Güdel; J. Hasiba; K. G. Isaak; L. L. Kiss; J. Laskar; A. Lecavelier Des Etangs; M. Lendl; C. Lovis; D. Magrin; P. F. L. Maxted; C. Mordasini; V. Nascimbeni; G. Olofsson; R. Ottensamer; I. Pagano; E. Pallé; G. Peter; G. Piotto; D. Pollacco; D. Queloz; R. Ragazzoni; N. Rando; H. Rauer; I. Ribas; N. C. Santos; G. Scandariato; D. Ségransan; A. E. Simon; A. M. S. Smith; M. Steller; N. Thomas; S. Udry; J. Venturini; V. Viotto; I. Walter; N. A. Walton

doi:10.1051/0004-6361/202346180

HR 10 as seen by CHEOPS and TESS: revealing δ Scuti pulsations, granulation-like signal and hint for transients

S. J. A. J. Salmon^*, V. Van Grootel, S. Sulis, Gy M. Szabó, A. Brandeker, C. Broeg, D. Ehrenreich, S. Hoyer, S. G. Sousa, F. Kiefer, D. Gandolfi, D. Nardiello, S. Charpinet, A. Bonfanti, T. G. Wilson, Y. Alibert, R. Alonso, G. Anglada, T. Bárczy, D. Barrado NavascuesS. C. C. Barros, W. Baumjohann, M. Beck, T. Beck, W. Benz, N. Billot, X. Bonfils, L. Borsato, J. Cabrera, V. Cessa, S. Charnoz, A. Collier Cameron, C. Corral Van Damme, Sz Csizmadia, P. E. Cubillos, M. B. Davies, M. Deleuil, L. Delrez, O. D. S. Demangeon, B. O. Demory, A. Erikson, A. Fortier, L. Fossati, M. Fridlund, M. Gillon, M. Güdel, J. Hasiba, K. G. Isaak, L. L. Kiss, J. Laskar, A. Lecavelier Des Etangs, M. Lendl, C. Lovis, D. Magrin, P. F. L. Maxted, C. Mordasini, V. Nascimbeni, G. Olofsson, R. Ottensamer, I. Pagano, E. Pallé, G. Peter, G. Piotto, D. Pollacco, D. Queloz, R. Ragazzoni, N. Rando, H. Rauer, I. Ribas, N. C. Santos, G. Scandariato, D. Ségransan, A. E. Simon, A. M. S. Smith, M. Steller, N. Thomas, S. Udry, J. Venturini, V. Viotto, I. Walter, N. A. Walton

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

Abstract

Context. HR 10 has only recently been identified as a binary system. Previously thought to be an A-type shell star, it appears that both components are fast-rotating A-type stars, each presenting a circumstellar envelope. Although showing complex photometric variability, spectroscopic observations of the metallic absorption lines reveal variation explained by the binarity, but not indicative of debris-disc inhomogeneities or sublimating exocomets. On the other hand, the properties of the two stars make them potential δ Scuti pulsators.
Aims. The system has been observed in two sectors by the TESS satellite, and was the target of three observing visits by CHEOPS. Thanks to these new data, we aim to further characterise the stellar properties of the two components. In particular, we aim to decipher the extent to which the photometric variability can be attributed to a stellar origin. In complement, we searched in the lightcurves for transient-type events that could reveal debris discs or exocomets.
Methods. We analysed the photometric variability of both the TESS and CHEOPS datasets in detail. We first performed a frequency analysis to identify and list all the periodic signals that may be related to stellar oscillations or surface variability. The signals identified as resulting from the stellar variability were then removed from the lightcurves in order to search for transient events in the residuals.
Results. We report the detection of δ Scuti pulsations in both the TESS and CHEOPS data, but we cannot definitively identify which of the components is the pulsating star. In both datasets, we find flicker noise with the characteristics of a stellar granulation signal. However, it remains difficult to firmly attribute it to actual stellar granulation from convection, given the very thin surface convective zones predicted for both stars. Finally, we report probable detection of transient events in the CHEOPS data, without clear evidence of their origin.

Original language	English
Article number	A73
Number of pages	18
Journal	Astronomy & Astrophysics
Volume	690
Early online date	1 Oct 2024
DOIs	https://doi.org/10.1051/0004-6361/202346180
Publication status	Published - Oct 2024

Keywords

Circumstellar matter
Stars: fundamental parameters
Stars: variables: δ Scuti
Sun: granulation
Techniques: photometric

Access to Document

10.1051/0004-6361/202346180Licence: CC BY

Salmon_2024_AandA_Revealing-delta-Scuti-pulsations_CC
Copyright © The Authors 2024. Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Final published version, 7.63 MBLicence: CC BY

1 Active
3 Finished

REVEAL: REVEALing Signatures of Habitable Worlds Hidden by Stellar Activity
Cameron, A. C. (PI)
UKRI (EU)
1/08/24 → 31/07/30
Project: Standard
AO2 - Professor Andrew Cameron: Project AO2 - Andrew Cameron
Cameron, A. C. (PI)
Science & Technology Facilities Council
1/04/21 → 31/03/24
Project: Standard
Astronomy at St Andrews 2018-2021: Astronomy at St Andrews 2018-2021
Jardine, M. M. (PI), Bonnell, I. A. (CoI), Cameron, A. C. (CoI), Cyganowski, C. J. (CoI), Dominik, M. (CoI), Helling, C. (CoI), Horne, K. D. (CoI), Scholz, A. (CoI), Tojeiro, R. (CoI), Weijmans, A.-M. (CoI), Wild, V. (CoI), Woitke, P. (CoI), Wood, K. (CoI) & Zhao, H. (CoI)
1/04/18 → 31/03/22
Project: Standard

Cite this

Salmon, S. J. A. J., Van Grootel, V., Sulis, S., Szabó, G. M., Brandeker, A., Broeg, C., Ehrenreich, D., Hoyer, S., Sousa, S. G., Kiefer, F., Gandolfi, D., Nardiello, D., Charpinet, S., Bonfanti, A., Wilson, T. G., Alibert, Y., Alonso, R., Anglada, G., Bárczy, T., ... Walton, N. A. (2024). HR 10 as seen by CHEOPS and TESS: revealing δ Scuti pulsations, granulation-like signal and hint for transients. Astronomy & Astrophysics, 690, Article A73. https://doi.org/10.1051/0004-6361/202346180

@article{ebd8746e84ac43b38bf8dd63c61df91f,

title = "HR 10 as seen by CHEOPS and TESS: revealing δ Scuti pulsations, granulation-like signal and hint for transients",

abstract = "Context. HR 10 has only recently been identified as a binary system. Previously thought to be an A-type shell star, it appears that both components are fast-rotating A-type stars, each presenting a circumstellar envelope. Although showing complex photometric variability, spectroscopic observations of the metallic absorption lines reveal variation explained by the binarity, but not indicative of debris-disc inhomogeneities or sublimating exocomets. On the other hand, the properties of the two stars make them potential δ Scuti pulsators. Aims. The system has been observed in two sectors by the TESS satellite, and was the target of three observing visits by CHEOPS. Thanks to these new data, we aim to further characterise the stellar properties of the two components. In particular, we aim to decipher the extent to which the photometric variability can be attributed to a stellar origin. In complement, we searched in the lightcurves for transient-type events that could reveal debris discs or exocomets.Methods. We analysed the photometric variability of both the TESS and CHEOPS datasets in detail. We first performed a frequency analysis to identify and list all the periodic signals that may be related to stellar oscillations or surface variability. The signals identified as resulting from the stellar variability were then removed from the lightcurves in order to search for transient events in the residuals. Results. We report the detection of δ Scuti pulsations in both the TESS and CHEOPS data, but we cannot definitively identify which of the components is the pulsating star. In both datasets, we find flicker noise with the characteristics of a stellar granulation signal. However, it remains difficult to firmly attribute it to actual stellar granulation from convection, given the very thin surface convective zones predicted for both stars. Finally, we report probable detection of transient events in the CHEOPS data, without clear evidence of their origin.",

keywords = "Circumstellar matter, Stars: fundamental parameters, Stars: variables: δ Scuti, Sun: granulation, Techniques: photometric",

author = "Salmon, {S. J. A. J.} and {Van Grootel}, V. and S. Sulis and Szab{\'o}, {Gy M.} and A. Brandeker and C. Broeg and D. Ehrenreich and S. Hoyer and Sousa, {S. G.} and F. Kiefer and D. Gandolfi and D. Nardiello and S. Charpinet and A. Bonfanti and Wilson, {T. G.} and Y. Alibert and R. Alonso and G. Anglada and T. B{\'a}rczy and {Barrado Navascues}, D. and Barros, {S. C. C.} and W. Baumjohann and M. Beck and T. Beck and W. Benz and N. Billot and X. Bonfils and L. Borsato and J. Cabrera and V. Cessa and S. Charnoz and {Collier Cameron}, A. and {Corral Van Damme}, C. and Sz Csizmadia and Cubillos, {P. E.} and Davies, {M. B.} and M. Deleuil and L. Delrez and Demangeon, {O. D. S.} and Demory, {B. O.} and A. Erikson and A. Fortier and L. Fossati and M. Fridlund and M. Gillon and M. G{\"u}del and J. Hasiba and Isaak, {K. G.} and Kiss, {L. L.} and J. Laskar and {Lecavelier Des Etangs}, A. and M. Lendl and C. Lovis and D. Magrin and Maxted, {P. F. L.} and C. Mordasini and V. Nascimbeni and G. Olofsson and R. Ottensamer and I. Pagano and E. Pall{\'e} and G. Peter and G. Piotto and D. Pollacco and D. Queloz and R. Ragazzoni and N. Rando and H. Rauer and I. Ribas and Santos, {N. C.} and G. Scandariato and D. S{\'e}gransan and Simon, {A. E.} and Smith, {A. M. S.} and M. Steller and N. Thomas and S. Udry and J. Venturini and V. Viotto and I. Walter and Walton, {N. A.}",

note = "Funding: CHEOPS is an ESA mission in partnership with Switzerland with important contributions to the payload and the ground segment from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden, and the United Kingdom. The CHEOPS Consortium would like to gratefully acknowledge the support received by all the agencies, offices, universities, and industries involved. Their flexibility and willingness to explore new approaches were essential to the success of this mission. This paper includes data collected by the TESS mission that are publicly available from the Mikulski Archive for Space Telescopes (MAST). Funding for the TESS mission is provided by NASA{\textquoteright}s Science Mission directorate. We are grateful to V. Antoci for helpful comments. SJAJS has received funding from the European Research Council (ERC) under the European Union{\textquoteright}s Horizon 2020 research and innovation program (grant agreement No 833925, project STAREX). VVG is an F.R.S-FNRS Research Associate. SS acknowledges the support from CNES, the Programme National de Plan{\'e}tologie (PNP), and the Programme National de Physique Stellaire (PNPS) of CNRS-INSU. GyMSz acknowledges the support of the Hungarian National Research, Development and Innovation Office (NKFIH) grant K-125015, a a PRODEX Experiment Agreement No. 4000137122, the Lend{\"u}let LP2018-7/2021 grant of the Hungarian Academy of Science and the support of the city of Szombathely. ABr was supported by the SNSA. This project has received funding from the European Research Council (ERC) under the European Union{\textquoteright}s Horizon 2020 research and innovation programme (project Four Aces. SH gratefully acknowledges CNES funding through the grant 837319. SGS acknowledges support from FCT through FCT contract nr. CEECIND/00826/2018 and POPH/FSE (EC). DG gratefully acknowledges financial support from the CRT foundation under Grant No. 2018.2323 “Gaseous or rocky? Unveiling the nature of small worlds”. SC acknowledges financial support from the Centre National d{\textquoteright}Etudes Spatiales (CNES, France) and from the Agence Nationale de la Recherche (ANR, France) under grant ANR-17- CE31-0018, funding the INSIDE project. ACC and TW acknowledge support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1. YAl acknowledges the support of the Swiss National Fund under grant 200020_172746. We acknowledge support from the Spanish Ministry of Science and Innovation and the European Regional Development Fund through grants ESP2016-80435-C2-1-R, ESP2016- 80435-C2-2-R, PGC2018-098153-B-C33, PGC2018-098153-B-C31, ESP2017- 87676-C5-1-R, MDM-2017-0737 Unidad de Excelencia Maria de MaeztuCentro de Astrobiolog{\'i}a (INTA-CSIC), as well as the support of the Generalitat de Catalunya/CERCA programme. The MOC activities have been supported by the ESA contract No. 4000124370. SCCB acknowledges support from FCT through FCT contracts nr. IF/01312/2014/CP1215/CT0004. XB, SC, DG, MF and JL acknowledge their role as ESA-appointed CHEOPS science team members. LBo, VNa, IPa, GPi, RRa, GSc, VSi, and TZi acknowledge support from CHEOPS ASI-INAF agreement n. 2019-29-HH.0. ACC acknowledges support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1. PEC is funded by the Austrian Science Fund (FWF) Erwin Schroedinger Fellowship, program J4595-N. This project was supported by the CNES. The Belgian participation to CHEOPS has been supported by the Belgian Federal Science Policy Office (BELSPO) in the framework of the PRODEX Program, and by the University of Li{\`e}ge through an ARC grant for Concerted Research Actions financed by the WalloniaBrussels Federation. LD is an F.R.S.-FNRS Postdoctoral Researcher. This work was supported by FCT – Funda{\c c}{\~a}o para a Ci{\^e}ncia e a Tecnologia through national funds and by FEDER through COMPETE2020 – Programa Operacional Competitividade e Internacionalizac{\~a}o by these grants: UID/FIS/04434/2019, UIDB/04434/2020, UIDP/04434/2020, PTDC/FIS-AST/32113/2017 and POCI01-0145-FEDER- 032113, PTDC/FIS-AST/28953/2017 and POCI-01-0145- FEDER-028953, PTDC/FIS-AST/28987/2017 and POCI-01-0145-FEDER028987, O.D.S.D. is supported in the form of work contract (DL 57/2016/CP1364/CT0004) funded by national funds through FCT. B-OD acknowledges support from the Swiss State Secretariat for Education, Research and Innovation (SERI) under contract number MB22.00046. MF and CMP gratefully acknowledge the support of the Swedish National Space Agency (DNR 65/19, 174/18). MG is an F.R.S.-FNRS Senior Research Associate. KGI is the ESA CHEOPS Project Scientist and is responsible for the ESA CHEOPS Guest Observers Programme. She does not participate in, or contribute to, the definition of the Guaranteed Time Programme of the CHEOPS mission through which observations described in this paper have been taken, nor to any aspect of target selection for the programme. This work was granted access to the HPC resources of MesoPSL financed by the Region Ile de France and the project Equip@Meso (reference ANR-10-EQPX-29-01) of the programme Investissements d{\textquoteright}Avenir supervised by the Agence Nationale pour la Recherche. ML acknowledges support of the Swiss National Science Foundation under grant number PCEFP2_194576. PM acknowledges support from STFC research grant number ST/M001040/1. This work was also partially supported by a grant from the Simons Foundation (PI Queloz, grant number 327127). IRI acknowledges support from the Spanish Ministry of Science and Innovation and the European Regional Development Fund through grant PGC2018-098153-B- C33, as well as the support of the Generalitat de Catalunya/CERCA programme. NAW acknowledges UKSA grant ST/R004838/1.",

year = "2024",

month = oct,

doi = "10.1051/0004-6361/202346180",

language = "English",

volume = "690",

journal = "Astronomy & Astrophysics",

issn = "0004-6361",

publisher = "EDP SCIENCES S A",

}

Salmon, SJAJ, Van Grootel, V, Sulis, S, Szabó, GM, Brandeker, A, Broeg, C, Ehrenreich, D, Hoyer, S, Sousa, SG, Kiefer, F, Gandolfi, D, Nardiello, D, Charpinet, S, Bonfanti, A, Wilson, TG, Alibert, Y, Alonso, R, Anglada, G, Bárczy, T, Barrado Navascues, D, Barros, SCC, Baumjohann, W, Beck, M, Beck, T, Benz, W, Billot, N, Bonfils, X, Borsato, L, Cabrera, J, Cessa, V, Charnoz, S, Collier Cameron, A, Corral Van Damme, C, Csizmadia, S, Cubillos, PE, Davies, MB, Deleuil, M, Delrez, L, Demangeon, ODS, Demory, BO, Erikson, A, Fortier, A, Fossati, L, Fridlund, M, Gillon, M, Güdel, M, Hasiba, J, Isaak, KG, Kiss, LL, Laskar, J, Lecavelier Des Etangs, A, Lendl, M, Lovis, C, Magrin, D, Maxted, PFL, Mordasini, C, Nascimbeni, V, Olofsson, G, Ottensamer, R, Pagano, I, Pallé, E, Peter, G, Piotto, G, Pollacco, D, Queloz, D, Ragazzoni, R, Rando, N, Rauer, H, Ribas, I, Santos, NC, Scandariato, G, Ségransan, D, Simon, AE, Smith, AMS, Steller, M, Thomas, N, Udry, S, Venturini, J, Viotto, V, Walter, I & Walton, NA 2024, 'HR 10 as seen by CHEOPS and TESS: revealing δ Scuti pulsations, granulation-like signal and hint for transients', Astronomy & Astrophysics, vol. 690, A73. https://doi.org/10.1051/0004-6361/202346180

TY - JOUR

T1 - HR 10 as seen by CHEOPS and TESS

T2 - revealing δ Scuti pulsations, granulation-like signal and hint for transients

AU - Salmon, S. J. A. J.

AU - Van Grootel, V.

AU - Sulis, S.

AU - Szabó, Gy M.

AU - Brandeker, A.

AU - Broeg, C.

AU - Ehrenreich, D.

AU - Hoyer, S.

AU - Sousa, S. G.

AU - Kiefer, F.

AU - Gandolfi, D.

AU - Nardiello, D.

AU - Charpinet, S.

AU - Bonfanti, A.

AU - Wilson, T. G.

AU - Alibert, Y.

AU - Alonso, R.

AU - Anglada, G.

AU - Bárczy, T.

AU - Barrado Navascues, D.

AU - Barros, S. C. C.

AU - Baumjohann, W.

AU - Beck, M.

AU - Beck, T.

AU - Benz, W.

AU - Billot, N.

AU - Bonfils, X.

AU - Borsato, L.

AU - Cabrera, J.

AU - Cessa, V.

AU - Charnoz, S.

AU - Collier Cameron, A.

AU - Corral Van Damme, C.

AU - Csizmadia, Sz

AU - Cubillos, P. E.

AU - Davies, M. B.

AU - Deleuil, M.

AU - Delrez, L.

AU - Demangeon, O. D. S.

AU - Demory, B. O.

AU - Erikson, A.

AU - Fortier, A.

AU - Fossati, L.

AU - Fridlund, M.

AU - Gillon, M.

AU - Güdel, M.

AU - Hasiba, J.

AU - Isaak, K. G.

AU - Kiss, L. L.

AU - Laskar, J.

AU - Lecavelier Des Etangs, A.

AU - Lendl, M.

AU - Lovis, C.

AU - Magrin, D.

AU - Maxted, P. F. L.

AU - Mordasini, C.

AU - Nascimbeni, V.

AU - Olofsson, G.

AU - Ottensamer, R.

AU - Pagano, I.

AU - Pallé, E.

AU - Peter, G.

AU - Piotto, G.

AU - Pollacco, D.

AU - Queloz, D.

AU - Ragazzoni, R.

AU - Rando, N.

AU - Rauer, H.

AU - Ribas, I.

AU - Santos, N. C.

AU - Scandariato, G.

AU - Ségransan, D.

AU - Simon, A. E.

AU - Smith, A. M. S.

AU - Steller, M.

AU - Thomas, N.

AU - Udry, S.

AU - Venturini, J.

AU - Viotto, V.

AU - Walter, I.

AU - Walton, N. A.

N1 - Funding: CHEOPS is an ESA mission in partnership with Switzerland with important contributions to the payload and the ground segment from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden, and the United Kingdom. The CHEOPS Consortium would like to gratefully acknowledge the support received by all the agencies, offices, universities, and industries involved. Their flexibility and willingness to explore new approaches were essential to the success of this mission. This paper includes data collected by the TESS mission that are publicly available from the Mikulski Archive for Space Telescopes (MAST). Funding for the TESS mission is provided by NASA’s Science Mission directorate. We are grateful to V. Antoci for helpful comments. SJAJS has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No 833925, project STAREX). VVG is an F.R.S-FNRS Research Associate. SS acknowledges the support from CNES, the Programme National de Planétologie (PNP), and the Programme National de Physique Stellaire (PNPS) of CNRS-INSU. GyMSz acknowledges the support of the Hungarian National Research, Development and Innovation Office (NKFIH) grant K-125015, a a PRODEX Experiment Agreement No. 4000137122, the Lendület LP2018-7/2021 grant of the Hungarian Academy of Science and the support of the city of Szombathely. ABr was supported by the SNSA. This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (project Four Aces. SH gratefully acknowledges CNES funding through the grant 837319. SGS acknowledges support from FCT through FCT contract nr. CEECIND/00826/2018 and POPH/FSE (EC). DG gratefully acknowledges financial support from the CRT foundation under Grant No. 2018.2323 “Gaseous or rocky? Unveiling the nature of small worlds”. SC acknowledges financial support from the Centre National d’Etudes Spatiales (CNES, France) and from the Agence Nationale de la Recherche (ANR, France) under grant ANR-17- CE31-0018, funding the INSIDE project. ACC and TW acknowledge support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1. YAl acknowledges the support of the Swiss National Fund under grant 200020_172746. We acknowledge support from the Spanish Ministry of Science and Innovation and the European Regional Development Fund through grants ESP2016-80435-C2-1-R, ESP2016- 80435-C2-2-R, PGC2018-098153-B-C33, PGC2018-098153-B-C31, ESP2017- 87676-C5-1-R, MDM-2017-0737 Unidad de Excelencia Maria de MaeztuCentro de Astrobiología (INTA-CSIC), as well as the support of the Generalitat de Catalunya/CERCA programme. The MOC activities have been supported by the ESA contract No. 4000124370. SCCB acknowledges support from FCT through FCT contracts nr. IF/01312/2014/CP1215/CT0004. XB, SC, DG, MF and JL acknowledge their role as ESA-appointed CHEOPS science team members. LBo, VNa, IPa, GPi, RRa, GSc, VSi, and TZi acknowledge support from CHEOPS ASI-INAF agreement n. 2019-29-HH.0. ACC acknowledges support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1. PEC is funded by the Austrian Science Fund (FWF) Erwin Schroedinger Fellowship, program J4595-N. This project was supported by the CNES. The Belgian participation to CHEOPS has been supported by the Belgian Federal Science Policy Office (BELSPO) in the framework of the PRODEX Program, and by the University of Liège through an ARC grant for Concerted Research Actions financed by the WalloniaBrussels Federation. LD is an F.R.S.-FNRS Postdoctoral Researcher. This work was supported by FCT – Fundação para a Ciência e a Tecnologia through national funds and by FEDER through COMPETE2020 – Programa Operacional Competitividade e Internacionalizacão by these grants: UID/FIS/04434/2019, UIDB/04434/2020, UIDP/04434/2020, PTDC/FIS-AST/32113/2017 and POCI01-0145-FEDER- 032113, PTDC/FIS-AST/28953/2017 and POCI-01-0145- FEDER-028953, PTDC/FIS-AST/28987/2017 and POCI-01-0145-FEDER028987, O.D.S.D. is supported in the form of work contract (DL 57/2016/CP1364/CT0004) funded by national funds through FCT. B-OD acknowledges support from the Swiss State Secretariat for Education, Research and Innovation (SERI) under contract number MB22.00046. MF and CMP gratefully acknowledge the support of the Swedish National Space Agency (DNR 65/19, 174/18). MG is an F.R.S.-FNRS Senior Research Associate. KGI is the ESA CHEOPS Project Scientist and is responsible for the ESA CHEOPS Guest Observers Programme. She does not participate in, or contribute to, the definition of the Guaranteed Time Programme of the CHEOPS mission through which observations described in this paper have been taken, nor to any aspect of target selection for the programme. This work was granted access to the HPC resources of MesoPSL financed by the Region Ile de France and the project Equip@Meso (reference ANR-10-EQPX-29-01) of the programme Investissements d’Avenir supervised by the Agence Nationale pour la Recherche. ML acknowledges support of the Swiss National Science Foundation under grant number PCEFP2_194576. PM acknowledges support from STFC research grant number ST/M001040/1. This work was also partially supported by a grant from the Simons Foundation (PI Queloz, grant number 327127). IRI acknowledges support from the Spanish Ministry of Science and Innovation and the European Regional Development Fund through grant PGC2018-098153-B- C33, as well as the support of the Generalitat de Catalunya/CERCA programme. NAW acknowledges UKSA grant ST/R004838/1.

PY - 2024/10

Y1 - 2024/10

N2 - Context. HR 10 has only recently been identified as a binary system. Previously thought to be an A-type shell star, it appears that both components are fast-rotating A-type stars, each presenting a circumstellar envelope. Although showing complex photometric variability, spectroscopic observations of the metallic absorption lines reveal variation explained by the binarity, but not indicative of debris-disc inhomogeneities or sublimating exocomets. On the other hand, the properties of the two stars make them potential δ Scuti pulsators. Aims. The system has been observed in two sectors by the TESS satellite, and was the target of three observing visits by CHEOPS. Thanks to these new data, we aim to further characterise the stellar properties of the two components. In particular, we aim to decipher the extent to which the photometric variability can be attributed to a stellar origin. In complement, we searched in the lightcurves for transient-type events that could reveal debris discs or exocomets.Methods. We analysed the photometric variability of both the TESS and CHEOPS datasets in detail. We first performed a frequency analysis to identify and list all the periodic signals that may be related to stellar oscillations or surface variability. The signals identified as resulting from the stellar variability were then removed from the lightcurves in order to search for transient events in the residuals. Results. We report the detection of δ Scuti pulsations in both the TESS and CHEOPS data, but we cannot definitively identify which of the components is the pulsating star. In both datasets, we find flicker noise with the characteristics of a stellar granulation signal. However, it remains difficult to firmly attribute it to actual stellar granulation from convection, given the very thin surface convective zones predicted for both stars. Finally, we report probable detection of transient events in the CHEOPS data, without clear evidence of their origin.

AB - Context. HR 10 has only recently been identified as a binary system. Previously thought to be an A-type shell star, it appears that both components are fast-rotating A-type stars, each presenting a circumstellar envelope. Although showing complex photometric variability, spectroscopic observations of the metallic absorption lines reveal variation explained by the binarity, but not indicative of debris-disc inhomogeneities or sublimating exocomets. On the other hand, the properties of the two stars make them potential δ Scuti pulsators. Aims. The system has been observed in two sectors by the TESS satellite, and was the target of three observing visits by CHEOPS. Thanks to these new data, we aim to further characterise the stellar properties of the two components. In particular, we aim to decipher the extent to which the photometric variability can be attributed to a stellar origin. In complement, we searched in the lightcurves for transient-type events that could reveal debris discs or exocomets.Methods. We analysed the photometric variability of both the TESS and CHEOPS datasets in detail. We first performed a frequency analysis to identify and list all the periodic signals that may be related to stellar oscillations or surface variability. The signals identified as resulting from the stellar variability were then removed from the lightcurves in order to search for transient events in the residuals. Results. We report the detection of δ Scuti pulsations in both the TESS and CHEOPS data, but we cannot definitively identify which of the components is the pulsating star. In both datasets, we find flicker noise with the characteristics of a stellar granulation signal. However, it remains difficult to firmly attribute it to actual stellar granulation from convection, given the very thin surface convective zones predicted for both stars. Finally, we report probable detection of transient events in the CHEOPS data, without clear evidence of their origin.

KW - Circumstellar matter

KW - Stars: fundamental parameters

KW - Stars: variables: δ Scuti

KW - Sun: granulation

KW - Techniques: photometric

U2 - 10.1051/0004-6361/202346180

DO - 10.1051/0004-6361/202346180

M3 - Article

AN - SCOPUS:85206330809

SN - 0004-6361

VL - 690

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

M1 - A73

ER -

HR 10 as seen by CHEOPS and TESS: revealing δ Scuti pulsations, granulation-like signal and hint for transients

Abstract

Keywords

Access to Document

Fingerprint

Projects

REVEAL: REVEALing Signatures of Habitable Worlds Hidden by Stellar Activity

AO2 - Professor Andrew Cameron: Project AO2 - Andrew Cameron

Astronomy at St Andrews 2018-2021: Astronomy at St Andrews 2018-2021

Cite this