We present optical photometric and spectroscopic observations of the likely stellar counterpart to the unassociated Fermi Large Area Telescope (LAT) γ-ray source 2FGL J0846.0+2820, selected for study ...based on positional coincidences of optical variables with unassociated LAT sources. Using optical spectroscopy from the SOAR telescope, we have identified a late-G giant in an eccentric (e = 0.06) 8.133-day orbit with an invisible primary. Modeling the spectroscopy and photometry together led us to infer a heavy neutron star primary of and a partially stripped giant secondary of . H emission is observed in some of the spectra, perhaps consistent with the presence of a faint accretion disk. We find that the γ-ray flux of 2FGL J0846.0+2820 dropped substantially in mid-2009, accompanied by an increased variation in the optical brightness, and since then, it has not been detected by Fermi. The long period and giant secondary are reminiscent of the γ-ray bright binary 1FGL J1417.7-4407, which hosts a millisecond pulsar (MSP) apparently in the final stages of the pulsar recycling process. The discovery of 2FGL J0846.0+2820 suggests the identification of a new subclass of MSP binaries that are the likely progenitors of typical field MSPs.
We report the discovery of KELT-10b, the first transiting exoplanet discovered using the KELT-South telescope. KELT-10b is a highly inflated sub-Jupiter mass planet transiting a relatively bright V = ...10.7 star (TYC 8378-64-1), with T
eff = 5948 ± 74 K, log g =
$4.319_{-0.030}^{+0.020}$
and Fe/H =
$0.09_{-0.10}^{+0.11}$
, an inferred mass M
* =
$1.112_{-0.061}^{+0.055}$
M⊙ and radius R
* =
$1.209_{-0.035}^{+0.047}$
R⊙. The planet has a radius R
p =
$1.399_{-0.049}^{+0.069}$
R
J and mass M
p =
$0.679_{-0.038}^{+0.039}$
M
J. The planet has an eccentricity consistent with zero and a semimajor axis a =
$0.052\,50_{-0.000\,97}^{+0.000\,86}$
au. The best-fitting linear ephemeris is T
0 = 2457 066.720 45 ± 0.000 27 BJDTDB and P = 4.166 2739 ± 0.000 0063 d. This planet joins a group of highly inflated transiting exoplanets with a larger radius and smaller mass than that of Jupiter. The planet, which boasts deep transits of 1.4 per cent, has a relatively high equilibrium temperature of T
eq =
$1377_{-23}^{+28}$
K, assuming zero albedo and perfect heat redistribution. KELT-10b receives an estimated insolation of
$0.817_{-0.054}^{+0.068}$
× 109 erg s−1 cm−2, which places it far above the insolation threshold above which hot Jupiters exhibit increasing amounts of radius inflation. Evolutionary analysis of the host star suggests that KELT-10b may not survive beyond the current subgiant phase, depending on the rate of in-spiral of the planet over the next few Gyr. The planet transits a relatively bright star and exhibits the third largest transit depth of all transiting exoplanets with V < 11 in the Southern hemisphere, making it a promising candidate for future atmospheric characterization studies.
ABSTRACT
The highly variable blazar OJ 287 is commonly discussed as an example of a binary black hole system. The 130 yr long optical light curve is well explained by a model where the central body ...is a massive black hole of 18.35 $\times$ 109 solar mass that supports a thin accretion disc. The secondary black hole of 0.15 $\times$ 109 solar mass impacts the disc twice during its 12 yr orbit, and causes observable flares. Recently, it has been argued that an accretion disc with a typical Active Galactic Nuclei (AGN) accretion rate and above mentioned central body mass should be at least six magnitudes brighter than OJ 287’s host galaxy and would therefore be observationally excluded. Based on the observations of OJ 287’s radio jet, detailed in Marscher and Jorstad (2011), and up-to-date accretion disc models of Azadi et al. (2022), we show that the V-band magnitude of the accretion disc is unlikely to exceed the host galaxy brightness by more than one magnitude, and could well be fainter than the host. This is because accretion power is necessary to launch the jet as well as to create electromagnetic radiation, distributed across many wavelengths, and not concentrated especially on the optical V-band. Further, we note that the claimed V-band concentration of accretion power leads to serious problems while interpreting observations of other AGN. Therefore, we infer that the mass of the primary black hole and its accretion rate do not need to be smaller than what is determined in the standard model for OJ 287.
ABSTRACT We present multiwavelength observations of the persistent Fermi-Large Area Telescope unidentified γ-ray source 1FGL J1417.7-4407, showing it is likely to be associated with a newly ...discovered X-ray binary containing a massive neutron star (nearly ) and a giant secondary with a 5.4 day period. SOAR optical spectroscopy at a range of orbital phases reveals variable double-peaked H emission, consistent with the presence of an accretion disk. The lack of radio emission and evidence for a disk suggests the γ-ray emission is unlikely to originate in a pulsar magnetosphere, but could instead be associated with a pulsar wind, relativistic jet, or could be due to synchrotron self-Compton at the disk-magnetosphere boundary. Assuming a wind or jet, the high ratio of γ-ray to X-ray luminosity (∼20) suggests efficient production of γ-rays, perhaps due to the giant companion. The system appears to be a low-mass X-ray binary that has not yet completed the pulsar recycling process. This system is a good candidate to monitor for a future transition between accretion-powered and rotational-powered states, but in the context of a giant secondary.
Abstract
We present high-cadence optical, ultraviolet (UV), and near-infrared data of the nearby (
D
≈ 23 Mpc) Type II supernova (SN) 2021yja. Many Type II SNe show signs of interaction with ...circumstellar material (CSM) during the first few days after explosion, implying that their red supergiant (RSG) progenitors experience episodic or eruptive mass loss. However, because it is difficult to discover SNe early, the diversity of CSM configurations in RSGs has not been fully mapped. SN 2021yja, first detected within ≈ 5.4 hours of explosion, shows some signatures of CSM interaction (high UV luminosity and radio and x-ray emission) but without the narrow emission lines or early light-curve peak that can accompany CSM. Here we analyze the densely sampled early light curve and spectral series of this nearby SN to infer the properties of its progenitor and CSM. We find that the most likely progenitor was an RSG with an extended envelope, encompassed by low-density CSM. We also present archival Hubble Space Telescope imaging of the host galaxy of SN 2021yja, which allows us to place a stringent upper limit of ≲ 9
M
☉
on the progenitor mass. However, this is in tension with some aspects of the SN evolution, which point to a more massive progenitor. Our analysis highlights the need to consider progenitor structure when making inferences about CSM properties, and that a comprehensive view of CSM tracers should be made to give a fuller view of the last years of RSG evolution.
Myocardial fibrosis is a key pathologic feature of hypertrophic cardiomyopathy (HCM). However, the fibrotic pathways activated by HCM-causing sarcomere protein gene mutations are poorly defined. ...Because lysophosphatidic acid is a mediator of fibrosis in multiple organs and diseases, we tested the role of the lysophosphatidic acid pathway in HCM. Lysphosphatidic acid receptor 1 (LPAR1), a cell surface receptor, is required for lysophosphatidic acid mediation of fibrosis. We bred HCM mice carrying a pathogenic myosin heavy-chain variant (403
) with
-ablated mice to create mice carrying both genetic changes (403
LPAR1
) and assessed development of cardiac hypertrophy and fibrosis. Compared with 403
LPAR1
, 403
LPAR1
mice developed significantly less hypertrophy and fibrosis. Single-nucleus RNA sequencing of left ventricular tissue demonstrated that
was predominantly expressed by lymphatic endothelial cells (LECs) and cardiac fibroblasts.
ablation reduced the population of LECs, confirmed by immunofluorescence staining of the LEC markers Lyve1 and Ccl21a and, by in situ hybridization, for
and
.
ablation also altered the distribution of fibroblast cell states. FB1 and FB2 fibroblasts decreased while FB0 and FB3 fibroblasts increased. Our findings indicate that
is expressed predominantly by LECs and fibroblasts in the heart and is required for development of hypertrophy and fibrosis in an HCM mouse model. LPAR1 antagonism, including agents in clinical trials for other fibrotic diseases, may be beneficial for HCM.
We report optical photometric and polarimetric observations of the blazar OJ 287 gathered during 2016/17. The high level of activity, noticed after the General Relativity Centenary flare, is argued ...to be part of the follow-up flares that exhibited high levels of polarization and originated in the primary black hole jet. We propose that the follow-up flares were induced as a result of accretion disk perturbations, travelling from the site of impact towards the primary SMBH. The timings inferred from our observations allowed us to estimate the propagation speed of these perturbations. Additionally, we make predictions for the future brightness of OJ 287.
Abstract
We present time-series CCD photometry in the
BVRI
passbands of the recently identified symbiotic nova V1835 Aquilae (NSV 11749) over an interval of 5.1 yr with 7–14 day cadence, observed ...during its quiescence. We find slow light variations with a range of ∼0.9 mag in
V
and ∼0.3 mag in
I
. Analysis of these data show strong periodicity at 419 ± 10 days, which we interpret to be the system’s orbital period. A dip in the otherwise-sinusoidal phased light curve suggests a weak ellipsoidal effect due to tidal distortion of the giant star, which in turn opens the possibility that V1835 Aql transfers some of its mass to the hot component via Roche lobe overflow rather than via a stellar wind. We also find evidence that V1835 Aql is an S-type symbiotic star, relatively free of circumstellar dust, and include it among the nuclear burning group of symbiotics. Finally, we provide photometry, periods, and light curve classifications for 22 variable stars in the field around V1835 Aql, about half of which are newly identified.
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