Mid-infrared circumstellar emission of the long-period Cepheid ℓ Carinae resolved with VLTI/MATISSE

Context. The nature of circumstellar envelopes (CSEs) around Cepheids is a matter of ongoing debate. The physical origin of their infrared (IR) excess could be shown to either be made up of a shell of ionized gas, a dust envelope, or a combination of both. Aims. This study is aimed at constraining the geometry and the IR excess of the environment of the bright long-period Cepheid ℓ Car (P = 35.5 days) at mid-IR wavelengths in order to understand its physical nature. Methods. We first used photometric observations in various bands (from the visible domain to the infrared) and Spitzer Space Telescope spectroscopy to constrain the IR excess of ℓ Car. Then we analyzed the VLTI/MATISSE measurements at a specific phase of observation in order to determine the flux contribution as well as the size and shape of the environment of the star in the L band. Finally, we tested the hypothesis of a shell of ionized gas in order to model the IR excess. Results. We report the first detection in the L band of a centro-symmetric extended emission around ℓ Car, of about 1.7 R⋆ in full width at half maximum, producing an excess of about 7.0% in this band.This latter value is used to calibrate the IR excess found when comparing the photometric observations in various bands and quasi-static atmosphere models. In the N band, there is no clear evidence for dust emission from VLTI/MATISSE correlated flux and Spitzer data. On the other side, the modeled shell of ionized gas implies a more compact CSE (1.13 ± 0.02 R⋆) that is also fainter (IR excess of 1% in the L band). Conclusions. We provide new evidence supporting a compact CSE for ℓ Car and we demonstrate the capabilities of VLTI/MATISSE for determining common properties of CSEs. While the compact CSE of ℓ Car is likely to be of a gaseous nature, the tested model of a shell of ionized gas is not able to simultaneously reproduce the IR excess and the interferometric observations. Further Galactic Cepheid observations with VLTI/MATISSE are necessary for determining the properties of CSEs, which may also depend on both the pulsation period and the evolutionary state of the stars.

G. Weigelt | R. Abuter | T. Henning | N. Hubin | F. Rigal | R. Roelfsema | F. Vakili | R. Waters | J. Augereau | L. Szabados | R. Brast | C. Dominik | J. Lizon | N. Schuhler | G. Zins | P. Bourget | J. Woillez | R. Frahm | L. Mohr | A. Matter | K. Hofmann | D. Schertl | I. Percheron | A. Chelli | R. Navarro | L. Venema | P. Girard | L. Pasquini | É. Pantin | R. Petrov | M. Delbo | W. Boland | J. Pott | E. Lagadec | L. Jochum | N. Nardetto | P. Kervella | A. Gallenne | W. Laun | C. Leinert | A. Glindemann | S. Morel | W. Danchi | F. Millour | A. D. D. Souza | P. Stee | R. Poole | M. D. Haan | A. M'erand | A. Chiavassa | L. Labadie | U. Graser | S. Rousseau | M. Hogerheijde | K. Meisenheimer | U. Beckmann | E. Kokoulina | T. P. Duc | S. Wolf | R. Conzelmann | G. Yoffe | T. Rivinius | P. Bristow | E. Elswijk | H. Hanenburg | J. Kragt | R. T. Horst | N. Tromp | J. Vinther | G. Bazin | R. Boekel | A. Soulain | G. Jakob | P. Bério | A. V. Duin | G. Kroes | M. Riquelme | S. Borgniet | M. Ebert | J. Hron | F. Bettonvil | D. Ives | L. Mehrgan | E. Pozna | M. Wittkowski | A. Gabasch | W. Jaffe | B. Lopez | M. Lehmitz | X. Haubois | U. Neumann | R. Rohloff | M. Scholler | L. Burtscher | M. Mellein | L. Pallanca | P. Cruzalèbes | C. Paladini | C. Bailet | Y. Bresson | M. Lopez | J. Herrera | A. Marcotto | P. 'Abrah'am | L. Klarmann | M. Schuil | L. Breuval | V. Hocd'e | S. Kuindersma | L. Mosoni | C. Connot | S. Lagarde | P. Antonelli | B. Javanmardi | R. Klein | F. Allouche | A. Meilland | M. Heininger | J. Isbell | J. Varga | V. G. Rosas | J. Meisner | S. Abadie | M. Accardo | T. Adler | T. Agócs | J. Beltrán | R. Castillo | C. Cid | J. Clausse | Y. Fantei | E. Garcés | P. Guajardo | F. Guitton | R. Huerta | A. Jask'o | N. Mauclert | T. Maurer | K. Meixner | E. Nussbaum | A. Ridinger | C. Stephan | F. Wrhel | G. Niccolini | A. Bohm | F. Gont'e | A. Glazenborg | J. Idserda | R. Buter | S.Robbe-Dubois | J. Alonso | K. Shabun | M. Delbo’ | B. López | E. Pantin | C. Dominik

[1]  W. Gieren,et al.  Extended envelopes around Galactic Cepheids , 2021, Astronomy & Astrophysics.

[2]  W. Gieren,et al.  Inspecting the Cepheid Distance Ladder: the Hubble Space Telescope Distance to the SN Ia Host Galaxy NGC 5584 , 2021, The Astrophysical Journal.

[3]  A. Riess,et al.  The Milky Way Cepheid Leavitt law based on Gaia DR2 parallaxes of companion stars and host open cluster populations , 2020, Astronomy & Astrophysics.

[4]  M. Groenewegen.  Analysing the spectral energy distributions of Galactic classical Cepheids , 2020, Astronomy & Astrophysics.

[5]  F. Millour,et al.  A catalogue of stellar diameters and fluxes for mid-infrared interferometry★ , 2019, Monthly Notices of the Royal Astronomical Society.

[6]  T. A. Lister,et al.  Gaia Data Release 2. Summary of the contents and survey properties , 2018, 1804.09365.

[7]  Adrian M. Price-Whelan,et al.  Binary Companions of Evolved Stars in APOGEE DR14: Search Method and Catalog of ∼5000 Companions , 2018, The Astronomical Journal.

[8]  W. Gieren,et al.  Observational calibration of the projection factor of Cepheids IV. Period-projection factor relation of Galactic and Magellanic Cloud Cepheids , 2017, 1708.09851.

[9]  A. Monreal-Ibero,et al.  Three-dimensional mapping of the local interstellar medium with composite data , 2017, 1706.07711.

[10]  Pierre Kervella,et al.  Observational calibration of the projection factor of Cepheids - III. The long-period Galactic Cepheid RS Puppis , 2017, 1701.05192.

[11]  N. N. Kireeva,et al.  General catalogue of variable stars: Version GCVS 5.1 , 2017 .

[12]  B. Pilecki,et al.  VEGA/CHARA interferometric observations of Cepheids - I. A resolved structure around the prototype classical Cepheid δ Cep in the visible spectral range , 2016, 1609.07268.

[13]  M. Accardo,et al.  MATISSE: alignment, integration, and test phase first results , 2016, Astronomical Telescopes + Instrumentation.

[14]  Florentin Millour,et al.  Data reduction for the MATISSE instrument , 2016, Astronomical Telescopes + Instrumentation.

[15]  Olivier Chesneau,et al.  Pseudomagnitudes and Differential Surface Brightness: Application to the apparent diameter of stars , 2016, 1604.07700.

[16]  E. Guinan,et al.  THE SECRET LIVES OF CEPHEIDS: EVOLUTION, MASS-LOSS, AND ULTRAVIOLET EMISSION OF THE LONG-PERIOD CLASSICAL CEPHEID , 2016, 1604.03128.

[17]  R. Beaton,et al.  The Carnegie Chicago Hubble Program: the mid-infrared colours of Cepheids and the effect of metallicity on the CO band-head at 4.6 μm , 2016, 1603.03776.

[18]  Pierre Kervella,et al.  Observational calibration of the projection factor of Cepheids - II. Application to nine Cepheids with HST/FGS parallax measurements , 2016, 1601.04727.

[19]  N. Mowlavi,et al.  Investigating Cepheid ℓ Carinae's cycle-to-cycle variations via contemporaneous velocimetry and interferometry , 2015, 1511.07089.

[20]  E. Schmidt.  EXCESS MID-INFRARED FLUX: AN INDICATOR OF MASS LOSS IN CEPHEIDS? , 2015 .

[21]  S. Ridgway,et al.  Cepheid distances from the SpectroPhoto-Interferometry of Pulsating Stars (SPIPS) - Application to the prototypes δ Cephei and η Aquilae , 2015, 1510.01940.

[22]  R. Anderson.  Tuning in on Cepheids: Radial velocity amplitude modulations - A source of systematic uncertainty for Baade-Wesselink distances , 2014, 1406.2605.

[23]  O. Chesneau,et al.  Extended envelopes around Galactic Cepheids IV. T Monocerotis and X Sagittarii from mid-infrared interferometry with VLTI/MIDI , 2013, 1309.0854.

[24]  S. E. Persson,et al.  THE CARNEGIE HUBBLE PROGRAM: THE LEAVITT LAW AT 3.6 AND 4.5 μm IN THE MILKY WAY , 2012, 1209.4946.

[25]  J. Bernard-Salas,et al.  CASSIS: THE CORNELL ATLAS OF SPITZER/INFRARED SPECTROGRAPH SOURCES. II. HIGH-RESOLUTION OBSERVATIONS , 2011, 1108.3507.

[26]  T. Henning.  Cosmic Silicates , 2011 .

[27]  Martin G. Cohen,et al.  THE WIDE-FIELD INFRARED SURVEY EXPLORER (WISE): MISSION DESCRIPTION AND INITIAL ON-ORBIT PERFORMANCE , 2010, 1008.0031.

[28]  Munetaka Ueno,et al.  The AKARI/IRC mid-infrared all-sky survey , 2010, 1003.0270.

[29]  John B. Davis,et al.  A list of bright interferometric calibrators measured at the European Southern Observatory Very Large Telescope Interferometer , 2009 .

[30]  B. Skiff,et al.  VizieR Online Data Catalog , 2009 .

[31]  W. Gieren,et al.  High-resolution spectroscopy for Cepheids distance determination V. Impact of the cross-correlation method on the p-factor and the γ-velocities , 2009, 0905.4540.

[32]  Pierre Kervella,et al.  The circumstellar envelopes of the Cepheids $\mathsf{\ell}$ Carinae and RS Puppis - Comparative study in the infrared with Spitzer, VLT/VISIR, and VLTI/MIDI , 2009, 0902.1588.

[33]  Denis Gillet,et al.  High-resolution spectroscopy for Cepheids distance determination IV. Time series of Hα line profiles , 2008 .

[34]  D. Bersier,et al.  High resolution spectroscopy for Cepheids distance determination. III. A relation between gamma-velocities and gamma-asymmetries , 2008, 0804.1331.

[35]  E. al.,et al.  Extended Envelopes around Galactic Cepheids. III. Y Ophiuchi and α Persei from Near-Infrared Interferometry with CHARA/FLUOR , 2007, 0704.1825.

[36]  P. Kervella.  Interferometric observations of η Carinae with VINCI/VLTI , 2006, astro-ph/0612264.

[37]  Pierre Kervella,et al.  Extended envelopes around Galactic Cepheids. II. Polaris and delta Cephei from near-infrared interfe , 2006 .

[38]  G. Perrin,et al.  Extended envelopes around Galactic Cepheids I. Carinae from near and mid-infrared interferometry with the VLTI , 2006 .

[39]  S. Mark Ammons,et al.  The N2K Consortium. IV. New Temperatures and Metallicities for More than 100,000 FGK Dwarfs , 2005, astro-ph/0510237.

[40]  S. Ridgway,et al.  The projection factor of δ Cephei A calibration of the Baade-Wesselink method using the CHARA Array , 2005, astro-ph/0506695.

[41]  D. Bersier,et al.  Self consistent modelling of the projection factor for interferometric distance determination , 2004 .

[42]  E. Wright,et al.  The Spitzer Space Telescope Mission , 2004, astro-ph/0406223.

[43]  J. R. Houck,et al.  The Infrared Spectrograph (IRS) on the Spitzer Space Telescope , 2004, astro-ph/0406167.

[44]  Beverly J. Smith,et al.  The COBE DIRBE Point Source Catalog , 2003, astro-ph/0406177.

[45]  D. Turner,et al.  Photoelectric Observations of Southern Cepheids in 2001 , 2001 .

[46]  Jean Kovalevsky,et al.  Astronomical Applications of Astrometry: The Hipparcos and Tycho Catalogues , 2008 .

[47]  Mark R. Kidger,et al.  Spectral Irradiance Calibration in the Infrared. X. A Self-Consistent Radiometric All-Sky Network of Absolutely Calibrated Stellar Spectra , 1999 .

[48]  M. A. C. Perryman,et al.  The Hipparcos and Tycho catalogues : astrometric and photometric star catalogues derived from the ESA Hipparcos Space Astrometry Mission , 1997 .

[49]  S. Love,et al.  Emission lines in the long-period Cepheid l Carinae , 1994 .

[50]  C. Skinner,et al.  The circumstellar environment of α Orionis , 1987 .

[51]  H. M. Lee,et al.  Optical properties of interstellar graphite and silicate grains , 1984 .

[52]  de T. Jong,et al.  The Infrared Astronomical Satellite (IRAS) mission , 1984 .

[53]  R. Snell,et al.  The infrared excess of cool giant stars - A chromospheric contribution , 1975 .

[54]  B. Madore.  Photoelectric UBV photometry of cepheids in the Magellanic Clouds and in the southern Milky Way. , 1975 .

[55]  R. Humphreys.  Veiling and the presence of circumstellar gas and dust in some infrared stars , 1974 .

[56]  R. C. Gilman.  Free--free and free-bound emission in low-surface-gravity stars , 1974 .

[57]  R. Bell,et al.  The Atmosphere of the Long Period Cepheid 1 Carinae: I. Curve of Growth Analysis and Hydrogen Line Profiles , 1968 .