OH/IR stars versus YSOs in infrared photometric surveys

2018 ◽  
Vol 14 (S343) ◽  
pp. 454-455
Author(s):  
Cécile Loup ◽  
Mark Allen ◽  
Ariane Lançon ◽  
Anais Oberto
Keyword(s):  
Selection Criteria ◽  
Far Infrared ◽  
High Mass ◽  
Agb Stars ◽  
Infrared Photometry ◽  
Mid Infrared ◽  
Ir Stars ◽  
High Mass Loss ◽  
Infrared Surveys ◽  
Methanol Masers

AbstractAGB stars play a major role in the chemical evolution of the galaxies. It thus is important to establish reliable photometric selection criteria to count them, especially AGB stars at the last stages of AGB evolution like OH/IR stars. Here, we have identified about 1500 OH/IR stars and 500 YSOs with methanol masers, in all major mid– and far–infrared surveys (IRAS, MSX, AKARI, WISE, GLIMPSE, and Hi–Gal). We show that AGB stars with high mass-loss rates cannot be disentagled from YSOs with only mid–infrared photometry; far–infrared photometry is essential. In the region observed by GLIMPSE, we show that the proportion of AGB stars has been severely underestimated in previous works: about 70% of “intrinsically” red objects in GLIMPSE are AGB stars rather than YSOs.

scholarly journals ISOCAM and DENIS Survey of 0.5 square degrees in the Bar of the LMC. Detection of the whole TP-AGB Star Population

1999 ◽  
Vol 191 ◽  
pp. 561-566
Author(s):  
C. Loup ◽  
E. Josselin ◽  
M.-R. Cioni ◽  
H.J. Habing ◽  
J.A.D.L. Blommaert ◽  
...  
Keyword(s):  
Mass Loss ◽  
High Mass ◽  
Evolutionary Models ◽  
Agb Stars ◽  
Complete Sample ◽  
High Mass Loss ◽  
Low Mass ◽  
The One ◽  
Good Agreement ◽  
Loss Rates

We surveyed 0.5 square degrees in the Bar of the LMC with ISOCAM at 4.5 and 12 μm, and with DENIS in the I, J, and Ks bands. Our goal was to build a complete sample of Thermally-Pulsing AGB stars. Here we present the first analysis of 0.14 square degrees. In total we find about 300 TP-AGB stars. Among these TP-AGB stars, 9% are obscured AGB stars (high mass-loss rates); 9 of them were detected by IRAS, and only 1 was previously identified. Their luminosities range from 2 500 to 14 000 L⊙, with a distribution very similar to the one of optical TP-AGB stars (i.e. those with low mass-loss rates). Such a luminosity distribution, as well as the percentage of obscured stars among TP-AGB stars, is in very good agreement with the evolutionary models of Vassiliadis & Wood (1993) if most of the TP-AGB stars that we find have initial masses smaller than 1.5 to 2 M⊙.

scholarly journals An ALMA view of SO and SO2 around oxygen-rich AGB stars

2020 ◽  
Vol 494 (1) ◽  
pp. 1323-1347 ◽  
Author(s):  
T Danilovich ◽  
A M S Richards ◽  
L Decin ◽  
M Van de Sande ◽  
C A Gottlieb
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Energy Levels ◽  
High Mass ◽  
High Angular Resolution ◽  
Circumstellar Envelope ◽  
Agb Stars ◽  
Abundance Distribution ◽  
High Mass Loss

ABSTRACT We present and analyse SO and SO2, recently observed with high angular resolution and sensitivity in a spectral line survey with ALMA, for two oxygen-rich AGB stars: the low mass-loss rate R Dor and high mass-loss rate IK Tau. We analyse 8 lines of SO detected towards both stars, 78 lines of SO2 detected towards R Dor, and 52 lines of SO2 detected towards IK Tau. We detect several lines of 34SO, 33SO, and 34SO2 towards both stars, and tentatively S18O towards R Dor, and hence derive isotopic ratios for these species. The spatially resolved observations show us that the two sulphur oxides are co-located towards R Dor and trace out the same wind structures in the circumstellar envelope. Much of the emission is well reproduced with a Gaussian abundance distribution spatially centred on the star. Emission from the higher energy levels of SO and SO2 towards R Dor provides evidence in support of a rotating inner region of gas identified in earlier work. The new observations allow us to refine the abundance distribution of SO in IK Tau derived from prior observations with single antennas, and confirm that the distribution is shell like with the peak in the fractional abundance not centred on the star. The confirmation of different types of SO abundance distributions will help fine-tune chemical models and allows for an additional method to discriminate between low and high mass-loss rates for oxygen-rich AGB stars.

Millimetre Observations of Evolved Stars

1996 ◽  
Vol 13 (2) ◽  
pp. 185-186
Author(s):  
Jessica M. Chapman
Keyword(s):  
Mass Loss ◽  
Stellar Atmosphere ◽  
Asymptotic Giant Branch ◽  
High Mass ◽  
Circumstellar Envelope ◽  
Agb Stars ◽  
Circumstellar Envelopes ◽  
Evolved Stars ◽  
High Mass Loss ◽  
Transfer Momentum

Radio emission at centimetre and millimetre wavelengths provides a powerful tool for studying the circumstellar envelopes of evolved stars. These include stars on the asymptotic giant branch (AGB), post-AGB stars and a small number of massive M-type supergiant stars. The AGB stars and M-type supergiants are characterised by extremely high mass-loss rates. The mass loss in such an evolved star is driven by radiation pressure acting on grains which form in the outer stellar atmosphere. The grains are accelerated outwards and transfer momentum to the gas through grain–gas collisions. The outflowing dust and gas thus form an expanding circumstellar envelope through which matter flows from the star to the interstellar medium, at a typical velocity of 15 km s−1. For a recent review of circumstellar mass loss see Chapman, Habing & Killeen (1995).

Infrared Surveys Planned for ASTRO-F

2005 ◽  
Vol 216 ◽  
pp. 347-352
Author(s):  
Hiroshi Shibai
Keyword(s):  
Far Infrared ◽  
Wide Field ◽  
Wavelength Band ◽  
Mid Infrared ◽  
Field Surveys ◽  
Infrared Wavelength ◽  
Sky Surveys ◽  
Sky Survey ◽  
Infrared Surveys ◽  
Higher Sensitivity

The next survey mission, ASTRO-F, is scheduled for launch in 2005. This is the first Japanese satellite dedicated to infrared astronomy. The primary purpose of this project is to investigate the birth and evolution of galaxies in the early universe through deep, wide-field surveys at wavelengths ranging from 2 to 200 microns. In the far-infrared wavelength band, ASTRO-F will conduct an all-sky survey like the IRAS survey with several tens of times higher sensitivity and several times better spatial resolution. In the near- and mid-infrared, wide area sky-surveys will be conducted over pre-selected portions of the sky in 13 bands ranging from 2-200microns. In addition to these photometric surveys, low-resolution spectroscopic capabilities are available for all wavelength bands. The ASTRO-F mission will produce a fundamental database for the next generation of advanced observatories, for example Herschel, and JWST, and will complement the SIRTF mission by virtue of its wide sky coverage.

scholarly journals The main sequence of star-forming galaxies – II. A non-evolving slope at the high-mass end

2019 ◽  
Vol 490 (4) ◽  
pp. 5285-5299 ◽  
Author(s):  
P Popesso ◽  
L Morselli ◽  
A Concas ◽  
C Schreiber ◽  
G Rodighiero ◽  
...  
Keyword(s):  
Main Sequence ◽  
Formation Rate ◽  
Selection Effect ◽  
Far Infrared ◽  
Stellar Mass ◽  
High Mass ◽  
Star Forming ◽  
Infrared Surveys ◽  
Local Relation ◽  
Stellar Masses

ABSTRACT By using the deepest available mid- and far-infrared surveys in the CANDELS, GOODS, and COSMOS fields we study the evolution of the main sequence (MS) of star-forming galaxies (SFGs) from z ∼ 0 to ∼ 2.5 at stellar masses larger than 1010 M⊙. The MS slope and scatter are consistent with a rescaled version of the local relation and distribution, shifted at higher values of star formation rate (SFR) according to ∝ (1 + $z$)3.2. The relation exhibits a bending at the high-mass end and a slightly increasing scatter as a function of the stellar mass. We show that the previously reported evolution of the MS slope, in the considered mass and redshift range, is due to a selection effect. The distribution of galaxies in the MS region at fixed stellar mass is well represented by a single lognormal distribution at all redshifts and masses, with starburst galaxies occupying the tail at high SFR.

scholarly journals High-mass-loss AGB Stars in the South Galactic Cap

1994 ◽  
Vol 267 (3) ◽  
pp. 711-742 ◽  
Author(s):  
P. Whitelock ◽  
J. Menzies ◽  
M. Feast ◽  
F. Marang ◽  
B. Carter ◽  
...  
Keyword(s):  
Mass Loss ◽  
High Mass ◽  
Agb Stars ◽  
The South ◽  
High Mass Loss

scholarly journals The Wolf-Rayet Connection - Luminous Blue Variables and Evolved Supergiants

1991 ◽  
Vol 143 ◽  
pp. 485-498
Author(s):  
Roberta M. Humphreys
Keyword(s):  
Mass Loss ◽  
Massive Stars ◽  
Physical Characteristics ◽  
High Mass ◽  
Luminous Blue Variables ◽  
Ir Stars ◽  
High Mass Loss ◽  
Stage 1 ◽  
And Behavior

The physical characteristics and behavior of evolved massive stars in three different mass ranges are reviewed with application to whether they may eventually evolve to the WR stage 1. >40-50 M⊙ as LBV's, 2. ∼30-40 M⊙ as cool hypergiant-OH/IR stars and 3. ∼10-30 M⊙ as red supergiant-OH/IR stars. I emphasize the importance of the relatively short but high mass loss phases as LBV's and as OH/IR stars in determining the fate of massive stars from 10 to 100 M⊙.

scholarly journals ISO's View of the Molecular Content of Evolved Stars

2000 ◽  
Vol 197 ◽  
pp. 375-390
Author(s):  
J. Cernicharo
Keyword(s):  
Systematic Study ◽  
Molecular Species ◽  
Planetary Nebulae ◽  
Far Infrared ◽  
Agb Stars ◽  
Circumstellar Envelopes ◽  
Mid Infrared ◽  
Evolved Stars ◽  
Vibrational Bands

The recent results of the ISO satellite in the field of molecular spectrocopy of AGB stars are reviewed. For the fist time, the two spectrometers onboard ISO have provided the opportunity to observe the pure rotational lines of several molecules in the far infrared and the ro-vibrational bands of the most abundant molecular species in the near and mid-infrared. These data allow to carry out a systematic study of the circumstellar envelopes of AGB stars and Planetary Nebulae. I analyze in this paper the role of resonant scatterring in the pumping of the ro-vibrational molecular levels in CSEs.

scholarly journals Binary post-AGB stars

1997 ◽  
Vol 180 ◽  
pp. 313-318 ◽  
Author(s):  
L.B.F.M. Waters ◽  
C. Waelkens ◽  
H. Van Winckel
Keyword(s):  
Mass Loss ◽  
Central Star ◽  
Asymptotic Giant Branch ◽  
High Mass ◽  
Agb Stars ◽  
Chemical Abundances ◽  
Intermediate Mass Stars ◽  
High Mass Loss ◽  
Complicating Factors ◽  
Circumstellar Environment

Low and intermediate mass stars leave the Asymptotic Giant Branch (AGB) when the mass in their H-rich envelope is less than about 0.01 M⊙, and the high mass loss drops several orders of magnitude. The central star rapidly evolves to the left part of the HR diagram along a track of constant luminosity (e.g. Schönberner 1983). In principle the evolution of the central star to higher Teff and the expansion and cooling of the AGB remnant are easy to calculate. In practice several complicating factors arise which make it much more difficult to predict the morphology and properties of post-AGB stars, such as binarity, post-AGB mass loss and aspherical AGB mass loss. Binarity of post-AGB stars affects the morphology of the circumstellar environment, and it affects evolutionary timescales and surface chemical abundances of the components in the system. This review discusses some properties of binary post-AGB stars.

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