J/A+A/653/A115 phi Leo spectra (Eiroa+, 2021)
The A-shell star phi Leo revisited: its photospheric and circumstellar spectra.
Eiroa C., Montesinos B., Rebollido I., Henning T., Launhardt R.,
Maldonado J., Meeus G., Mora A., Riviere-Marichalar P., Villaver E.
<Astron. Astrophys. 653, A115 (2021)>
=2021A&A...653A.115E 2021A&A...653A.115E (SIMBAD/NED BibCode)
ADC_Keywords: Stars, A-type ; Spectroscopy
Keywords: stars: individual: phi Leo - stars: early-type -
stars: variables: delta Scuti - stars: emission-line, Be -
circumstellar matter - comets: general
Abstract:
Variable red- and blue-shifted absorption features observed in the
CaII K line towards the A-type shell star φ Leo have been
suggested by us in a previous work to be likely due to solid,
comet-like bodies in the circumstellar (CS) environment.
Our aim is to expand our observational study of this object to other
characteristic spectral lines of A-type photospheres as well as to
lines arising in their CS shells.
We have obtained more than 500 high-resolution optical spectra
collected at different telescopes during 37 nights in several
observing runs from December 2015 to January 2019. Time series
consecutive spectra were taken, covering intervals of up to ∼9 hours
in some nights. We have analysed some photospheric lines, in
particular CaI 4226Å and MgII 4481Å, as well as the
circumstellar shell lines CaII H&K, CaII IR triplet, FeII 4924, 5018
and 5169Å, TiII 3685, 3759 and 3761Å, and the Balmer lines
Hα and Hβ.
Our observational study reveals that φ Leo is a variable delta
Scuti star whose spectra show remarkable dumps and bumps superimposed
on the photospheric line profiles, which vary their strength and
sharpness, propagate from blue- to more red-shifted radial velocities
and persisting during a few hours. Similarly t o other delta Scuti
stars, these features are likely produced by non-radial pulsations. At
the same time, all shell lines present an emission at ∼3km/s centered
at the core of the CS features, and two variable absorption minima at
both sides of the emission; those absorption minima occur at
practically the same velocity for each line, i.e., no apparent
dynamical evolution is observed. The variations observed in the CaII
H&K, FeII and TiII lines occur at any time scale from minutes to days
and observing run, but without any clear correlation or recognizable
temporal pattern among the different lines. In the case of Hα
the CS contribution is also variable in just one of the observing
runs.
Summarizing, we suggest that φ Leo is a rapidly rotating delta
Scuti star surrounded by a variable, (nearly) edge-on CS disk possibly
re-supplied by the delta Scuti pulsations. The behaviour of the CS
shell lines is reminiscent of the one observed in rapidly rotating Be
shell stars with an edge-on CS disk, and clearly points out that the
variations observed in the CS features of φ Leo are highly
unlikely to be produced by exocomets. In addition, the observational
results presented in this work, together with some recent results
concerning the shell star HR 10, suggest the need of a critical
revision of the CaII K features which have been attributed to
exocomets in other shell stars.
Description:
The table, which appears in the paper as Table C.1, contains the log
of the high-resolution spectroscopic observations used in the paper to
carry out the analysis of the variable circumstellar features
superimposed to several photospheric lines. Date, UT of the
observations, and the spectrograph used are listed.
Spectra obtained with Mercator (La Palma, Spain), NOT (La Palma,
Spain), 2.2 MPG (La Silla, Chile), CARMENES (Calar Alto, Spain) and
HARPS-N (La Palma, Spain) echelle spectrographs.
Objects:
-----------------------------------------------
RA (2000) DE Designation(s)
-----------------------------------------------
11 16 39.70 -03 39 05.8 phi Leo = HR 4368
-----------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablec1.dat 28 568 Log of the spectroscopic observations
list.dat 79 569 List of observed spectra for phi Leo
sp/* . 569 Individual spectra
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See also:
J/A+A/639/A11 : Exocomets. A Spectroscopic Survey (Rebollido+, 2020)
Byte-by-byte Description of file: tablec1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 "date" Date Date of observation
13- 17 A5 "h:m" Time Time at the beginning of the observation
22- 28 A7 --- Inst Spectrograph name
(FEROS, FIES, HARPS-N or HERMES)
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Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Inst Spectrograph name
(FEROS, FIES, HARPS-N or HERMES)
9- 33 A25 "datime" Obs.date Observation date
35- 79 A45 --- FileName Name of the spectrum file in subdirectory sp
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Byte-by-byte Description of file: sp/*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 F19.13 0.1nm lambda Wavelength
21- 44 E24.18 --- Flux ?=- Flux
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Acknowledgements:
Benjamin Montesinos, bmm(at)cab.inta-csic.es
(End) Benjamin Montesinos [CAB, CSIC-INTA], Patricia Vannier [CDS] 06-Jul-2021