---
res:
  bibo_abstract:
  - Neutral sodium (Na i) is an alkali metal with a favorable absorption cross section
    such that tenuous gases are easily illuminated at select transiting exoplanet
    systems. We examine both the time-averaged and time-series alkali spectral flux
    individually, over 4 nights at a hot Saturn system on a ∼2.8 day orbit about a
    Sun-like star WASP-49 A. Very Large Telescope/ESPRESSO observations are analyzed,
    providing new constraints. We recover the previously confirmed residual sodium
    flux uniquely when averaged, whereas night-to-night Na i varies by more than an
    order of magnitude. On HARPS/3.6 m Epoch II, we report a Doppler redshift at vΓ,NaD
    = + 9.7 ± 1.6 km s−1 with respect to the planet's rest frame. Upon examining the
    lightcurves, we confirm night-to-night variability, on the order of ∼1%–4% in
    NaD, rarely coinciding with exoplanet transit, not readily explained by stellar
    activity, starspots, tellurics, or the interstellar medium. Coincident with the
    ∼+10 km s−1 Doppler redshift, we detect a transient sodium absorption event dFNaD/F⋆
    = 3.6% ± 1% at a relative difference of ΔFNaD(t) ∼ 4.4% ± 1%, lasting ΔtNaD ≳
    40 minutes. Since exoplanetary alkali signatures are blueshifted due to the natural
    vector of radiation pressure, estimated here at roughly ∼−5.7 km s−1, the radial
    velocity is rather at +15.4 km s−1, far larger than any known exoplanet system.
    Given that the redshift magnitude vΓ is in between the Roche limit and dynamically
    stable satellite orbits, the transient sodium may be a putative indication of
    a natural satellite orbiting WASP-49 A b.@eng
  bibo_authorlist:
  - foaf_Person:
      foaf_givenName: Apurva V.
      foaf_name: Oza, Apurva V.
      foaf_surname: Oza
  - foaf_Person:
      foaf_givenName: Julia V.
      foaf_name: Seidel, Julia V.
      foaf_surname: Seidel
  - foaf_Person:
      foaf_givenName: H. Jens
      foaf_name: Hoeijmakers, H. Jens
      foaf_surname: Hoeijmakers
  - foaf_Person:
      foaf_givenName: Athira
      foaf_name: Unni, Athira
      foaf_surname: Unni
  - foaf_Person:
      foaf_givenName: Aurora Y.
      foaf_name: Kesseli, Aurora Y.
      foaf_surname: Kesseli
  - foaf_Person:
      foaf_givenName: Carl A.
      foaf_name: Schmidt, Carl A.
      foaf_surname: Schmidt
  - foaf_Person:
      foaf_givenName: Thirupathi
      foaf_name: Sivarani, Thirupathi
      foaf_surname: Sivarani
  - foaf_Person:
      foaf_givenName: Aaron
      foaf_name: Bello-Arufe, Aaron
      foaf_surname: Bello-Arufe
  - foaf_Person:
      foaf_givenName: Andrea
      foaf_name: Gebek, Andrea
      foaf_surname: Gebek
  - foaf_Person:
      foaf_givenName: Moritz
      foaf_name: Meyer Zu Westram, Moritz
      foaf_surname: Meyer Zu Westram
  - foaf_Person:
      foaf_givenName: Sérgio G.
      foaf_name: Sousa, Sérgio G.
      foaf_surname: Sousa
  - foaf_Person:
      foaf_givenName: Rosaly M.C.
      foaf_name: Lopes, Rosaly M.C.
      foaf_surname: Lopes
  - foaf_Person:
      foaf_givenName: Renyu
      foaf_name: Hu, Renyu
      foaf_surname: Hu
  - foaf_Person:
      foaf_givenName: Katherine
      foaf_name: De Kleer, Katherine
      foaf_surname: De Kleer
  - foaf_Person:
      foaf_givenName: Chloe
      foaf_name: Fisher, Chloe
      foaf_surname: Fisher
  - foaf_Person:
      foaf_givenName: Sébastien
      foaf_name: Charnoz, Sébastien
      foaf_surname: Charnoz
  - foaf_Person:
      foaf_givenName: Ashley D.
      foaf_name: Baker, Ashley D.
      foaf_surname: Baker
  - foaf_Person:
      foaf_givenName: Samuel P.
      foaf_name: Halverson, Samuel P.
      foaf_surname: Halverson
  - foaf_Person:
      foaf_givenName: Nick M.
      foaf_name: Schneider, Nick M.
      foaf_surname: Schneider
  - foaf_Person:
      foaf_givenName: Angelica
      foaf_name: Psaridi, Angelica
      foaf_surname: Psaridi
  - foaf_Person:
      foaf_givenName: Aurélien
      foaf_name: Wyttenbach, Aurélien
      foaf_surname: Wyttenbach
  - foaf_Person:
      foaf_givenName: Santiago
      foaf_name: Torres Rodriguez, Santiago
      foaf_surname: Torres Rodriguez
      foaf_workInfoHomepage: http://www.librecat.org/personId=a8df4360-4328-11ee-8f1a-e502d0c83fc2
    orcid: 0000-0002-3150-8988
  - foaf_Person:
      foaf_givenName: Ishita
      foaf_name: Bhatnagar, Ishita
      foaf_surname: Bhatnagar
  - foaf_Person:
      foaf_givenName: Robert E.
      foaf_name: Johnson, Robert E.
      foaf_surname: Johnson
  bibo_doi: 10.3847/2041-8213/ad6b29
  bibo_issue: '2'
  bibo_volume: 973
  dct_date: 2024^xs_gYear
  dct_identifier:
  - UT:001322169500001
  dct_isPartOf:
  - http://id.crossref.org/issn/2041-8205
  - http://id.crossref.org/issn/2041-8213
  dct_language: eng
  dct_publisher: IOP Publishing@
  dct_title: Redshifted sodium transient near exoplanet transit@
...