- ID:
- ivo://CDS.VizieR/J/ApJS/232/16
- Title:
- Mira stars discovered in LAMOST DR4
- Short Name:
- J/ApJS/232/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on an extensive spectral study of a photometrically confirmed sample of Mira variables, we find a relationship between the relative Balmer emission-line strengths and spectral temperatures of O-rich Mira stars. The F_H{delta}_/F_H{gamma}_ flux ratio increases from less than unity to five as stars cool down from M0 to M10, which is likely driven by increasing TiO absorption above the deepest shock-emitting regions. We also discuss the relationship between the equivalent widths of the Balmer emission lines and the photometric luminosity phase of our Mira sample stars. Using our 291 Mira spectra as templates for reference, 191 Mira candidates are newly identified from the LAMOST DR4 catalog. We summarize the criteria adopted to select Mira candidates based on emission-line indices and molecular absorption bands. This enlarged spectral sample of Mira variables has the potential to contribute significantly to our knowledge of the optical properties of Mira stars and will facilitate further studies of these late-type, long-period variables.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/443/143
- Title:
- Mira Variables in the OGLE Bulge fields
- Short Name:
- J/A+A/443/143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 222000 I-band light curves of variable stars detected by the OGLE-II survey in the direction of the Galactic Bulge have been fitted and also correlated with the DENIS and 2MASS all-sky release databases and with lists of known objects. Light-curves and the results of the light-curve fitting (periods and amplitudes) and DENIS and 2MASS data are presented for 2691 objects with I-band semi-amplitude larger than 0.45 magnitude, corresponding to classical Mira variables.
- ID:
- ivo://CDS.VizieR/J/A+AS/120/275
- Title:
- Mira variables light curves
- Short Name:
- J/A+AS/120/275
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Good distance indicators are needed in studies of the galactic structure. Pulsating variables can be used, but the problem is to find a homogeneous sample obeying a period-luminosity relation with low scatter. In this paper, we show how such a sample can be produced using the Terzan catalogue of Variables and available Schmidt plates. We have selected 150 large amplitude variables discovered by Terzan in a field of 25 sq degrees near the Galactic Centre. A set of 22 red plates was scanned with the MAMA machine, providing time series for all the variables. The times series were analysed using both the periodogram and Renson's method. Periods could be derived for 122 stars of the sample showing clearly that most of these objects are Miras. As a conclusion we show that with some infrared photometry, these Miras could be used as good distance indicators in this region.
- ID:
- ivo://CDS.VizieR/J/other/NewA/17.504
- Title:
- Mira variables om ROTSE-IIId
- Short Name:
- J/other/NewA/17.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have studied the long-term variations of Mira type variables observed with Robotic Optical Transient Search Experiment telescope (ROTSE-IIId) between 2004 and 2009 located at TUBITAK National Observatory (TUG) in Antalya, Turkey. The actual pulsation periods, variability amplitudes, epochs of maximums and light curves of selected 70 Mira type variables already defined in the SIMBAD database were investigated. In these variables, 17 periods are identified for the first time
- ID:
- ivo://CDS.VizieR/J/A+A/599/A29
- Title:
- MIR brightness contrast of Saturn's rings
- Short Name:
- J/A+A/599/A29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To investigate the mid-infrared (MIR) characteristics of Saturn's rings. We collected and analyzed MIR high spatial resolution images of Saturn's rings obtained in January 2008 and April 2005 with COMICS mounted on Subaru Telescope, and investigated the spatial variation in the surface brightness of the rings in multiple bands in the MIR. We also composed the spectral energy distributions (SEDs) of the C, B, and A rings and the Cassini Division, and estimated the temperatures of the rings from the SEDs assuming the optical depths. We find that the C ring and the Cassini Division were warmer than the B and A rings in 2008, which could be accounted for by their lower albedos, lower optical depths, and smaller self-shadowing effect. We also find that the C ring and the Cassini Division were considerably brighter than the B and A rings in the MIR in 2008 and the radial contrast of the ring brightness is the inverse of that in 2005, which is interpreted as a result of a seasonal effect with changing elevations of the sun and observer above the ring plane.
- ID:
- ivo://CDS.VizieR/J/ApJ/705/1364
- Title:
- MIR catalog of point sources in M33
- Short Name:
- J/ApJ/705/1364
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The progenitors of SN 2008S and the 2008 luminous transient in NGC 300 were deeply dust-enshrouded massive stars, with extremely red mid-infrared (MIR) colors and relatively low bolometric luminosities (~5x10^4^L_{sun}_). Because of the implied frequency of events similar to SN 2008S and NGC 300 and the interesting character of their progenitors, we searched for analogous sources in archival Spitzer imaging of nearby galaxies. Our goal was to identify the underlying subpopulation of massive stars from which these progenitors emerge, to characterize their properties and frequency, and to catalog them for future study. The Triangulum galaxy M33 is a perfect test case. It has an absolute B-band magnitude of M_B_~-19.2, a distance of ~0.96Mpc, and it has extensive optical, H{alpha}, MIR and FIR imaging.
- ID:
- ivo://CDS.VizieR/J/ApJS/252/32
- Title:
- MIR outbursts in nearby SDSS gal. (MIRONG). I.
- Short Name:
- J/ApJS/252/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical time-domain astronomy has grown rapidly in the past decade, but the dynamic infrared sky is rarely explored. Aiming to construct a sample of mid-infrared outbursts in nearby galaxies (MIRONG), we have conducted a systematical search of low-redshift (z<0.35) Sloan Digital Sky Survey spectroscopic galaxies that have experienced recent mid-infrared (MIR) flares using their Wide-field Infrared Survey Explorer (WISE) light curves. A total of 137 galaxies have been selected by requiring a brightening amplitude of 0.5mag in at least one WISE band with respect to their quiescent phases. Only a small fraction (10.9%) has corresponding optical flares. Except for the four supernovae (SNe) in our sample, the MIR luminosities of the remaining sources (L_4.6{mu}m_>10^42^erg/s) are markedly brighter than known SNe, and their physical locations are very close to the galactic center (median <0.1"). Only four galaxies are radio-loud, indicating that synchrotron radiation from relativistic jets could contribute to MIR variability. We propose that these MIR outbursts are dominated by the dust echoes of transient accretion onto supermassive black holes, such as tidal disruption events (TDEs) and turn-on (changing-look) active galactic nuclei. Moreover, the inferred peak MIR luminosity function is generally consistent with the X-ray and optical TDEs at the high end, albeit with large uncertainties. Our results suggest that a large population of transients has been overlooked by optical surveys, probably due to dust obscuration or intrinsically optical weakness. Thus, a search in the infrared band is crucial for us to obtain a panoramic picture of nuclear outburst. The multiwavelength follow-up observations of the MIRONG sample are in progress and will be presented in a series of subsequent papers.
- ID:
- ivo://CDS.VizieR/J/ApJ/800/80
- Title:
- MIR properties of galaxies in A2199 at z~0.03
- Short Name:
- J/ApJ/800/80
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the mid-infrared (MIR) properties of the galaxies in the A2199 supercluster at z=0.03 to understand the star formation activity of galaxy groups and clusters in the supercluster environment. Using the Wide-field Infrared Survey Explorer (WISE) data, we find no dependence of mass-normalized integrated star formation rates of galaxy groups/clusters on their virial masses. We classify the supercluster galaxies into three classes in the MIR color-luminosity diagram: MIR blue cloud (massive, quiescent, and mostly early-type), MIR star-forming sequence (mostly late-type), and MIR green valley galaxies. These MIR green valley galaxies are distinguishable from the optical green valley galaxies in the sense that they belong to the optical red sequence. We find that the fraction of each MIR class does not depend on the virial mass of each group/cluster. We compare the cumulative distributions of surface galaxy number density and cluster/group-centric distance for the three MIR classes. MIR green valley galaxies show the distribution between MIR blue cloud and MIR star-forming (SF) sequence galaxies. However, if we fix galaxy morphology, early- and late-type MIR green valley galaxies show different distributions. Our results suggest a possible evolutionary scenario of these galaxies: (1) late-type MIR SF sequence galaxies --> (2) late-type MIR green valley galaxies --> (3) early-type MIR green valley galaxies --> (4) early-type MIR blue cloud galaxies. In this sequence, the star formation of galaxies is quenched before the galaxies enter the MIR green valley, and then morphological transformation occurs in the MIR green valley.
- ID:
- ivo://CDS.VizieR/J/ApJ/886/33
- Title:
- MIR reverberation mapping analysis of 87 z<0.5 PG AGNs
- Short Name:
- J/ApJ/886/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The continued operation of the Wide-field Infrared Survey Explorer (WISE), combined with several ground-based optical transient surveys (e.g., CRTS, ASAS-SN, and PTF), offers an unprecedented opportunity to explore the dust structures in luminous active galactic nuclei (AGNs). We use these data for a mid-IR dust reverberation mapping (RM) study of 87 archetypal Palomar-Green quasars at z<~0.5. To cope with various contaminations of the photometry data and the sparse time sampling of the light curves, procedures to combine these data sets and retrieve the dust RM signals have been developed. We find that ~70% of the sample (with a completeness correction up to 95%) has convincing mid-IR time lags in the WISE W1 (~3.4{mu}m) and W2 (~4.5{mu}m) bands, and they are proportional to the square root of the AGN luminosity. Combined with previous K-band (~2.2{mu}m) RM results in the literature, the inferred dust emission size ratios are R_K_:R_W1_:R_W2_=0.6:1:1.2. Under simple assumptions, we put preliminary constraints on the projected dust surface density at these bands and reveal the possibly different torus structures among hot-dust-deficient, warm-dust-deficient, and normal quasars from the reverberation signals. With multi-epoch Spitzer data and later WISE photometry, we also explore AGN IR variability at 10-24{mu}m over a 5yr timescale. Except for blazars and flat-spectrum radio sources, the majority of AGNs have typical variation amplitudes at 24{mu}m of no more than 10% of that in the W1 band, indicating that the dust reverberation signals damp out quickly at longer wavelengths. In particular, steep-spectrum radio quasars also lack strong 24{mu}m variability, consistent with the unification picture of radio-loud AGNs.
- ID:
- ivo://CDS.VizieR/J/ApJ/791/113
- Title:
- MIR-selected quasar parameters
- Short Name:
- J/ApJ/791/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We provide a catalog of 391 mid-infrared-selected (MIR; 24 {mu}m) broad-emission-line (BEL; type 1) quasars in the 22 deg^2^ SWIRE Lockman Hole field. This quasar sample is selected in the MIR from Spitzer MIPS with S_24_> 400 {mu}Jy, jointly with an optical magnitude limit of r(AB) < 22.5 for broad line identification. The catalog is based on MMT and Sloan Digital Sky Survey (SDSS) spectroscopy to select BEL quasars, extending the SDSS coverage to fainter magnitudes and lower redshifts, and recovers a more complete quasar population. The MIR-selected quasar sample peaks at z ~ 1.4 and recovers a significant and constant (20%) fraction of extended objects with SDSS photometry across magnitudes, which were not included in the SDSS quasar survey dominated by point sources. This sample also recovers a significant population of z < 3 quasars at i > 19.1. We then investigate the continuum luminosity and line profiles of these MIR quasars, and estimate their virial black hole masses and the Eddington ratios. The supermassive black hole mass shows evidence of downsizing, although the Eddington ratios remain constant at 1 < z < 4. Compared to point sources in the same redshift range, extended sources at z < 1 show systematically lower Eddington ratios. The catalog and spectra are publicly available online.
